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• 6 Interesting Facts About NASA’s Mars Rover ‘Curiosity’

  - by Gopinath

  Humans quest for exploring the surrounding planets to see whether we can live there or not is taking new shape today. NASA’s Mars probing robot, Curiosity, blasted off today on its 9 months journey to reach Mars and explore it for the possibilities of life there. Scientist says that Curiosity is one most advanced rover ever launched to probe life on other planets. Here is the launch video and some analysis by a news reporter Lets look at the 6 interesting facts about the mission 1. It’s as big as a car Curiosity is the biggest ever rover ever launched by NASA to probe life on outer planets. It’s as big as a car and almost double the size of its predecessor rover Spirit. The length of Curiosity is around 9 feet 10 inches(3 meters), width is 9 feet 1 inch (2.8 meters) and height is 7 feet (2.1 meters). 2. Powered by Plutonium – Lasts 24×7 for 23 months The earlier missions of NASA to explore Mars are powered by Solar power and that hindered capabilities of the rovers to move around when the Sun is hiding. Due to dependency of Sun the earlier rovers were not able to traverse the places where there is no Sun light. Curiosity on the other hand is equipped with a radioisotope power system that generates electricity from the heat emitted by plutonium’s radioactive decay. The plutonium weighs around 10 pounds and can generate power required for operating the rover close to 23 weeks. The best part of the new power system is, Curiosity can roam around in darkness, light and all year around. 3. Rocket powered backpack for a science fiction style landing The Curiosity is so heavy that NASA could not use parachute and balloons to air-drop the rover on the surface of Mars like it’s previous missions. They are trying out a new science fiction style air-dropping mechanism that is similar to sky crane heavy-lift helicopter. The landing of the rover begins first with entry into the Mars atmosphere protected by a heat shield. At about 6 miles to the surface, the heat shield is jettisoned and a parachute is deployed to glide the rover smoothly. When the rover touches 3 miles above the surface, the parachute is jettisoned and the eight motors rocket backpack is used for a smooth and impact free landing as shown in the image. Here is an animation created by NASA on the landing sequence. If you are interested in getting more detailed information about the landing process check this landing sequence picture available on NASA website 4. Equipped with Star Wars style laser gun Hollywood movie directors and novelist always imagined aliens coming to earth with spaceships full of laser guns and blasting the objects which comes on their way. With Curiosity the equations are going to change. It has a powerful laser gun equipped in one of it’s arms to beam laser on rocks to vaporize them. This is not part of any assault mission Curiosity is expected to carry out, the laser gun is will be used to carry out experiments to detect life and understand nature. 5. Most sophisticated laboratory powered by 10 instruments Around 10 state of art instruments are part of Curiosity rover and the these 10 instruments form a most advanced rover based lab ever built by NASA. There are instruments to cut through rocks to examine them and other instruments will search for organic compounds. Mounted cameras can study targets from a distance, arm mounted instruments can study the targets they touch. Microscopic lens attached to the arm can see and magnify tiny objects as tiny as 12.5 micro meters. 6. Rover Carrying 1.24 million names etched on silicon Early June 2009 NASA launched a campaign called “Send Your Name to Mars” and around 1.24 million people registered their names through NASA’s website. All those 1.24 million names are etched on Silicon chips mounted onto Curiosity’s deck. If you had registered your name in the campaign may be your name is going to reach Mars soon. Curiosity On Web If you wish to follow the mission here are few links to help you NASA’s Curiosity Web Page Follow Curiosity on Facebook Follow @MarsCuriosity on Twitter Artistic Gallery Image of Mars Rover Curiosity A printable sheet of Curiosity Mission [pdf] Images credit: NASA This article titled,6 Interesting Facts About NASA’s Mars Rover ‘Curiosity’, was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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• 6 Reasons Why You Can’t Move Your Cell Phone To Any Carrier You Want

  - by Chris Hoffman

  You can buy a laptop or Wi-Fi tablet and use it on Wi-Fi anywhere in the world, so why are cell phones and devices with mobile data not portable between different cellular networks in the same country? Unlike with Wi-Fi, there are many different competing cellular network standards — both around the world and within countries. Cellular carriers also like locking you to their specific network and making it difficult to move. That’s what contracts are for. Phone Locking Many phones are sold locked to a specific network. When you buy a phone from a cellular carrier, they often lock that phone to their network so you can’t take it to a competitor’s network. That’s why you’ll often need to unlock a phone before you can move it to a different cellular provider or take it to a different country and use it on a local provider instead of roaming. Cellular carriers will generally unlock your phone for you as long as you’re no longer in a contract with them. However, unlocking a cell phone you’ve paid for without your carrier’s permission is currently a crime in the USA. GSM vs. CDMA Some cellular networks use the GSM (Global System for Mobile Communications) standard, while some use CDMA (Code-division multiple access). Worldwide, most cellular networks use GSM. In the USA, both GSM and CDMA are popular. Verizon, Sprint, and other carriers that use their networks use CDMA. AT&T, T-Mobile, and other carriers that use their networks are use GSM. These are two competing standards and are not interoperable. This means you can’t simply take a phone from Verizon to T-Mobile, or from AT&T to Sprint. These carriers have incompatible phones. CDMA Restrictions CDMA is more restricted than GSM. GSM phones have SIM cards. Simply open the phone, pop out the SIM card, and pop in a new SIM card to switch carriers. (In reality, it’s more complicated thanks to phone locking and other factors here.) CDMA phones don’t have removable modules like this. All CDMA phones ship locked to a specific network and you’d have to get both your old carrier and your new carrier to cooperate to switch phones between them. In reality, many people just consider CDMA phones eternally locked to a specific carrier. Frequencies Different cellular networks throughout the USA and the rest of the world use different frequencies. These radio frequencies have to be supported by your phone’s hardware or your phone simply can’t work on a network using those frequencies. Many GSM phones support three or four bands of frequencies — 900/1800/1900 MHz, 850/1800/1900 MHz, or 850/900/1800/1900 MHz. These are sometimes called “world phones” because they allow easier roaming. This allows the manufacturer to produce a phone that will support all GSM networks in the world and allows their customers to travel with those phones. If your phone doesn’t support the appropriate frequencies, it won’t work on certain networks. LTE Bands When it comes to newer, faster LTE networks, different frequencies are still a concern. LTE frequencies are generally known as “LTE bands.” To use a smartphone on a certain LTE network, that smartphone will have to support that LTE network’s frequency. Different models of phones are often created to work on different LTE networks around the world. However, phones are generally supporting more and more LTE networks and becoming more and more interoperable over time. SIM Card Sizes The SIM cards used in GSM phones come in different sizes. Newer phones use smaller SIM cards to save space and be more compact. This isn’t a big obstacle, as the different sizes of SIM cards — full-size SIM, mini-SIM, micro-SIM, and nano-SIM are actually compatible. The only difference between them is the size of the plastic card surrounding the SIM’s chip. The actual chip is the same size between all the SIM cards. This means you can take an old SIM card and cut the plastic off until it becomes a smaller-size SIM card that fits in a modern phone. Or, you can take a smaller-size SIM card and insert it into a tray so that it becomes a larger-size SIM card that fits in an older phone. Be aware that it’s very possible to damage your SIM card and make it not work properly by cutting it to the wrong dimensions. Your cellular carrier will often be able to cut your SIM card for you or give you a new one if you want to use an old SIM card in a new phone. Hopefully they won’t overcharge you for this service, too. Be sure to check what types of networks, frequencies, and LTE bands your phone supports before trying to move it between networks. You may have to buy a new phone when moving between certain cellular carriers. Image Credit: Morgan on Flickr, 22n on Flickr

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• Troubleshooting High-CPU Utilization for SQL Server

  - by Susantha Bathige

  The objective of this FAQ is to outline the basic steps in troubleshooting high CPU utilization on  a server hosting a SQL Server instance. The first and the most common step if you suspect high CPU utilization (or are alerted for it) is to login to the physical server and check the Windows Task Manager. The Performance tab will show the high utilization as shown below: Next, we need to determine which process is responsible for the high CPU consumption. The Processes tab of the Task Manager will show this information: Note that to see all processes you should select Show processes from all user. In this case, SQL Server (sqlserver.exe) is consuming 99% of the CPU (a normal benchmark for max CPU utilization is about 50-60%). Next we examine the scheduler data. Scheduler is a component of SQLOS which evenly distributes load amongst CPUs. The query below returns the important columns for CPU troubleshooting. Note – if your server is under severe stress and you are unable to login to SSMS, you can use another machine’s SSMS to login to the server through DAC – Dedicated Administrator Connection (see http://msdn.microsoft.com/en-us/library/ms189595.aspx for details on using DAC) SELECT scheduler_id ,cpu_id ,status ,runnable_tasks_count ,active_workers_count ,load_factor ,yield_count FROM sys.dm_os_schedulers WHERE scheduler_id See below for the BOL definitions for the above columns. scheduler_id – ID of the scheduler. All schedulers that are used to run regular queries have ID numbers less than 1048576. Those schedulers that have IDs greater than or equal to 1048576 are used internally by SQL Server, such as the dedicated administrator connection scheduler. cpu_id – ID of the CPU with which this scheduler is associated. status – Indicates the status of the scheduler. runnable_tasks_count – Number of workers, with tasks assigned to them that are waiting to be scheduled on the runnable queue. active_workers_count – Number of workers that are active. An active worker is never preemptive, must have an associated task, and is either running, runnable, or suspended. current_tasks_count - Number of current tasks that are associated with this scheduler. load_factor – Internal value that indicates the perceived load on this scheduler. yield_count – Internal value that is used to indicate progress on this scheduler.                                                                 Now to interpret the above data. There are four schedulers and each assigned to a different CPU. All the CPUs are ready to accept user queries as they all are ONLINE. There are 294 active tasks in the output as per the current_tasks_count column. This count indicates how many activities currently associated with the schedulers. When a  task is complete, this number is decremented. The 294 is quite a high figure and indicates all four schedulers are extremely busy. When a task is enqueued, the load_factor  value is incremented. This value is used to determine whether a new task should be put on this scheduler or another scheduler. The new task will be allocated to less loaded scheduler by SQLOS. The very high value of this column indicates all the schedulers have a high load. There are 268 runnable tasks which mean all these tasks are assigned a worker and waiting to be scheduled on the runnable queue.   The next step is  to identify which queries are demanding a lot of CPU time. The below query is useful for this purpose (note, in its current form,  it only shows the top 10 records). SELECT TOP 10 st.text  ,st.dbid  ,st.objectid  ,qs.total_worker_time  ,qs.last_worker_time  ,qp.query_plan FROM sys.dm_exec_query_stats qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) st CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp ORDER BY qs.total_worker_time DESC This query as total_worker_time as the measure of CPU load and is in descending order of the  total_worker_time to show the most expensive queries and their plans at the top:      Note the BOL definitions for the important columns: total_worker_time - Total amount of CPU time, in microseconds, that was consumed by executions of this plan since it was compiled. last_worker_time - CPU time, in microseconds, that was consumed the last time the plan was executed.   I re-ran the same query again after few seconds and was returned the below output. After few seconds the SP dbo.TestProc1 is shown in fourth place and once again the last_worker_time is the highest. This means the procedure TestProc1 consumes a CPU time continuously each time it executes.      In this case, the primary cause for high CPU utilization was a stored procedure. You can view the execution plan by clicking on query_plan column to investigate why this is causing a high CPU load. I have used SQL Server 2008 (SP1) to test all the queries used in this article.

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• AWS: setting up auto-scale for EC2 instances

  - by Elton Stoneman

  Originally posted on: http://geekswithblogs.net/EltonStoneman/archive/2013/10/16/aws-setting-up-auto-scale-for-ec2-instances.aspxWith Amazon Web Services, there’s no direct equivalent to Azure Worker Roles – no Elastic Beanstalk-style application for .NET background workers. But you can get the auto-scale part by configuring an auto-scaling group for your EC2 instance. This is a step-by-step guide, that shows you how to create the auto-scaling configuration, which for EC2 you need to do with the command line, and then link your scaling policies to CloudWatch alarms in the Web console. I’m using queue size as my metric for CloudWatch,  which is a good fit if your background workers are pulling messages from a queue and processing them.  If the queue is getting too big, the “high” alarm will fire and spin up a new instance to share the workload. If the queue is draining down, the “low” alarm will fire and shut down one of the instances. To start with, you need to manually set up your app in an EC2 VM, for a background worker that would mean hosting your code in a Windows Service (I always use Topshelf). If you’re dual-running Azure and AWS, then you can isolate your logic in one library, with a generic entry point that has Start() and Stop()  functions, so your Worker Role and Windows Service are essentially using the same code. When you have your instance set up with the Windows Service running automatically, and you’ve tested it starts up and works properly from a reboot, shut the machine down and take an image of the VM, using Create Image (EBS AMI) from the Web Console: When that completes, you’ll have your own AMI which you can use to spin up new instances, and you’re ready to create your auto-scaling group. You need to dip into the command-line tools for this, so follow this guide to set up the AWS autoscale command line tool. Now we’re ready to go. 1. Create a launch configuration This launch configuration tells AWS what to do when a new instance needs to be spun up. You create it with the as-create-launch-config command, which looks like this: as-create-launch-config sc-xyz-launcher # name of the launch config --image-id ami-7b9e9f12 # id of the AMI you extracted from your VM --region eu-west-1 # which region the new instance gets created in --instance-type t1.micro # size of the instance to create --group quicklaunch-1 #security group for the new instance 2. Create an auto-scaling group The auto-scaling group links to the launch config, and defines the overall configuration of the collection of instances: as-create-auto-scaling-group sc-xyz-asg # auto-scaling group name --region eu-west-1 # region to create in --launch-configuration sc-xyz-launcher # name of the launch config to invoke for new instances --min-size 1 # minimum number of nodes in the group --max-size 5 # maximum number of nodes in the group --default-cooldown 300 # period to wait (in seconds) after each scaling event, before checking if another scaling event is required --availability-zones eu-west-1a eu-west-1b eu-west-1c # which availability zones you want your instances to be allocated in – multiple entries means EC@ will use any of them 3. Create a scale-up policy The policy dictates what will happen in response to a scaling event being triggered from a “high” alarm being breached. It links to the auto-scaling group; this sample results in one additional node being spun up: as-put-scaling-policy scale-up-policy # policy name -g sc-psod-woker-asg # auto-scaling group the policy works with --adjustment 1 # size of the adjustment --region eu-west-1 # region --type ChangeInCapacity # type of adjustment, this specifies a fixed number of nodes, but you can use PercentChangeInCapacity to make an adjustment relative to the current number of nodes, e.g. increasing by 50% 4. Create a scale-down policy The policy dictates what will happen in response to a scaling event being triggered from a “low” alarm being breached. It links to the auto-scaling group; this sample results in one node from the group being taken offline: as-put-scaling-policy scale-down-policy -g sc-psod-woker-asg "--adjustment=-1" # in Windows, use double-quotes to surround a negative adjustment value –-type ChangeInCapacity --region eu-west-1 5. Create a “high” CloudWatch alarm We’re done with the command line now. In the Web Console, open up the CloudWatch view and create a new alarm. This alarm will monitor your metrics and invoke the scale-up policy from your auto-scaling group, when the group is working too hard. Configure your metric – this example will fire the alarm if there are more than 10 messages in my queue for over a minute: Then link the alarm to the scale-up policy in your group: 6. Create a “low” CloudWatch alarm The opposite of step 4, this alarm will trigger when the instances in your group don’t have enough work to do (e.g fewer than 2 messages in the queue for 1 minute), and will invoke the scale-down policy. And that’s it. You don’t need your original VM as the auto-scale group has a minimum number of nodes connected. You can test out the scaling by flexing your CloudWatch metric – in this example, filling up a queue from a  stub publisher – and watching AWS create new nodes as required, then stopping the publisher and watch AWS kill off the spare nodes.

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• Measuring Usability with Common Industry Format (CIF) Usability Tests

  - by Applications User Experience

  Sean Rice, Manager, Applications User Experience A User-centered Research and Design Process The Oracle Fusion Applications user experience was five years in the making. The development of this suite included an extensive and comprehensive user experience design process: ethnographic research, low-fidelity workflow prototyping, high fidelity user interface (UI) prototyping, iterative formative usability testing, development feedback and iteration, and sales and customer evaluation throughout the design cycle. However, this process does not stop when our products are released. We conduct summative usability testing using the ISO 25062 Common Industry Format (CIF) for usability test reports as an organizational framework. CIF tests allow us to measure the overall usability of our released products.  These studies provide benchmarks that allow for comparisons of a specific product release against previous versions of our product and against other products in the marketplace. What Is a CIF Usability Test? CIF refers to the internationally standardized method for reporting usability test findings used by the software industry. The CIF is based on a formal, lab-based test that is used to benchmark the usability of a product in terms of human performance and subjective data. The CIF was developed and is endorsed by more than 375 software customer and vendor organizations led by the National Institute for Standards and Technology (NIST), a US government entity. NIST sponsored the CIF through the American National Standards Institute (ANSI) and International Organization for Standardization (ISO) standards-making processes. Oracle played a key role in developing the CIF. The CIF report format and metrics are consistent with the ISO 9241-11 definition of usability: “The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.” Our goal in conducting CIF tests is to measure performance and satisfaction of a representative sample of users on a set of core tasks and to help predict how usable a product will be with the larger population of customers. Why Do We Perform CIF Testing? The overarching purpose of the CIF for usability test reports is to promote incorporation of usability as part of the procurement decision-making process for interactive products. CIF provides a common format for vendors to report the methods and results of usability tests to customer organizations, and enables customers to compare the usability of our software to that of other suppliers. CIF also enables us to compare our current software with previous versions of our software. CIF Testing for Fusion Applications Oracle Fusion Applications comprises more than 100 modules in seven different product families. These modules encompass more than 400 task flows and 400 user roles. Due to resource constraints, we cannot perform comprehensive CIF testing across the entire product suite. Therefore, we had to develop meaningful inclusion criteria and work with other stakeholders across the applications development organization to prioritize product areas for testing. Ultimately, we want to test the product areas for which customers might be most interested in seeing CIF data. We also want to build credibility with customers; we need to be able to make the case to current and prospective customers that the product areas tested are representative of the product suite as a whole. Our goal is to test the top use cases for each product. The primary activity in the scoping process was to work with the individual product teams to identify the key products and business process task flows in each product to test. We prioritized these products and flows through a series of negotiations among the user experience managers, product strategy, and product management directors for each of the primary product families within the Oracle Fusion Applications suite (Human Capital Management, Supply Chain Management, Customer Relationship Management, Financials, Projects, and Procurement). The end result of the scoping exercise was a list of 47 proposed CIF tests for the Fusion Applications product suite.  Figure 1. A participant completes tasks during a usability test in Oracle’s Usability Labs Fusion Supplier Portal CIF Test The first Fusion CIF test was completed on the Supplier Portal application in July of 2011.  Fusion Supplier Portal is part of an integrated suite of Procurement applications that helps supplier companies manage orders, schedules, shipments, invoices, negotiations and payments. The user roles targeted for the usability study were Supplier Account Receivables Specialists and Supplier Sales Representatives, including both experienced and inexperienced users across a wide demographic range.  The test specifically focused on the following functionality and features: Manage payments – view payments Manage invoices – view invoice status and create invoices Manage account information – create new contact, review bank account information Manage agreements – find and view agreement, upload agreement lines, confirm status of agreement lines upload Manage purchase orders (PO) – view history of PO, request change to PO, find orders Manage negotiations – respond to request for a quote, check the status of a negotiation response These product areas were selected to represent the most important subset of features and functionality of the flow, in terms of frequency and criticality of use by customers. A total of 20 users participated in the usability study. The results of the Supplier Portal evaluation were favorable and exceeded our expectations. Figure 2. Fusion Supplier Portal Next Studies We plan to conduct two Fusion CIF usability studies per product family over the next nine months. The next product to be tested will be Self-service Procurement. End users are currently being recruited to participate in this usability study, and the test sessions are scheduled to begin during the last week of November.

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• HDFC Bank's Journey to Oracle Private Database Cloud

  - by Nilesh Agrawal

  One of the key takeaways from a recent post by Sushil Kumar is the importance of business initiative that drives the transformational journey from legacy IT to enterprise private cloud. The journey that leads to a agile, self-service and efficient infrastructure with reduced complexity and enables IT to deliver services more closely aligned with business requirements. Nilanjay Bhattacharjee, AVP, IT of HDFC Bank presented a real-world case study based on one such initiative in his Oracle OpenWorld session titled "HDFC BANK Journey into Oracle Database Cloud with EM 12c DBaaS". The case study highlighted in this session is from HDFC Bank’s Lending Business Segment, which comprises roughly 50% of Bank’s top line. Bank’s Lending Business is always under pressure to launch “New Schemes” to compete and stay ahead in this segment and IT has to keep up with this challenging business requirement. Lending related applications are highly dynamic and go through constant changes and every single and minor change in each related application is required to be thoroughly UAT tested certified before they are certified for production rollout. This leads to a constant pressure in IT for rapid provisioning of UAT databases on an ongoing basis to enable faster time to market. Nilanjay joined Sushil Kumar, VP, Product Strategy, Oracle, during the Enterprise Manager general session at Oracle OpenWorld 2012. Let's watch what Nilanjay had to say about their recent Database cloud deployment. “Agility” in launching new business schemes became the key business driver for private database cloud adoption in the Bank. Nilanjay spent an hour discussing it during his session. Let's look at why Database-as-a-Service(DBaaS) model was need of the hour in this case  - Average 3 days to provision UAT Database for Loan Management Application Silo’ed UAT environment with Average 30% utilization Compliance requirement consume UAT testing resources DBA activities leads to $$ paid to SI for provisioning databases manually Overhead in managing configuration drift between production and test environments Rollout impact/delay on new business initiatives The private database cloud implementation progressed through 4 fundamental phases - Standardization, Consolidation, Automation, Optimization of UAT infrastructure. Project scoping was carried out and end users and stakeholders were engaged early on right from planning phase and including all phases of implementation. Standardization and Consolidation phase involved multiple iterations of planning to first standardize on infrastructure, db versions, patch levels, configuration, IT processes etc and with database level consolidation project onto Exadata platform. It was also decided to have existing AIX UAT DB landscape covered and EM 12c DBaaS solution being platform agnostic supported this model well. Automation and Optimization phase provided the necessary Agility, Self-Service and efficiency and this was made possible via EM 12c DBaaS. EM 12c DBaaS Self-Service/SSA Portal was setup with required zones, quotas, service templates, charge plan defined. There were 2 zones implemented - Exadata zone  primarily for UAT and benchmark testing for databases running on Exadata platform and second zone was for AIX setup to cover other databases those running on AIX. Metering and Chargeback/Showback capabilities provided business and IT the framework for cloud optimization and also visibility into cloud usage. More details on UAT cloud implementation, related building blocks and EM 12c DBaaS solution are covered in Nilanjay's OpenWorld session here. Some of the key Benefits achieved from UAT cloud initiative are - New business initiatives can be easily launched due to rapid provisioning of UAT Databases [ ~3 hours ] Drastically cut down $$ on SI for DBA Activities due to Self-Service Effective usage of infrastructure leading to  better ROI Empowering  consumers to provision database using Self-Service Control on project schedule with DB end date aligned to project plan submitted during provisioning Databases provisioned through Self-Service are monitored in EM and auto configured for Alerts and KPI Regulatory requirement of database does not impact existing project in queue This table below shows typical list of activities and tasks involved when a end user requests for a UAT database. EM 12c DBaaS solution helped reduce UAT database provisioning time from roughly 3 days down to 3 hours and this timing also includes provisioning time for database with production scale data (ranging from 250 G to 2 TB of data) - And it's not just about time to provision,  this initiative has enabled an agile, efficient and transparent UAT environment where end users are empowered with real control of cloud resources and IT's role is shifted as enabler of strategic services instead of being administrator of all user requests. The strong collaboration between IT and business community right from planning to implementation to go-live has played the key role in achieving this common goal of enterprise private cloud. Finally, real cloud is here and this cloud is accompanied with rain (business benefits) as well ! For more information, please go to Oracle Enterprise Manager  web page or  follow us at :  Twitter | Facebook | YouTube | Linkedin | Newsletter

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• Oracle SQL Developer v3.2.1 Now Available

  - by thatjeffsmith

  Oracle SQL Developer version 3.2.1 is now available. I recommend that everyone now upgrade to this release. It features more than 200 bug fixes, tweaks, and polish applied to the 3.2 edition. The high profile bug fixes submitted by customers and users on our forums are listed in all their glory for your review. I want to highlight a few of the changes though, as I recognize many of you lack the time and/or patience to ‘read the docs.’ That would include me, which is why I enjoy writing these kinds of blog posts. I’m lazy – just like you! No more artificial line breaks between CREATE OR REPLACE and your PL/SQL In versions 3.2 and older, when you pull up your stored procedural objects in our editor, you would see a line break inserted between the CREATE OR REPLACE and then the body of your code. In version 3.2.1, we have removed the line break. 3.1 3.2.1 Trivia Did You Know? The database doesn’t store the ‘CREATE’ or ‘CREATE OR REPLACE’ bit of your PL/SQL code in the database. If we look at the USER_SOURCE view, we can see that the code begins with the object name. So the CREATE OR REPLACE bit is ‘artificial’ The intent is to give you the code necessary to recreate your object – and have it ‘compile’ into the database. We pretty much HAVE to add the ‘CREATE OR REPLACE.’ From now on it will appear inline with the first line of your code. Exporting Tables & Views When exporting data from your tables or views, previous versions of SQL Developer presented a 3 step wizard. It allows you to choose your columns and apply data filters for what is exported. This was kind of redundant. The grids already allowed you to select your columns and apply filters. Wouldn’t it be more intuitive AND efficient to just make the grids behave in a What You See Is What You Get (WYSIWYG) fashion? In version 3.2.1, that is exactly what will happen. The wizard now only has two steps and the grid will export the data and columns as defined in the visible grid. Let the grid properties define what is actually exported! And here is what is pasted into my worksheet: "BREWERY"|"CITY" "3 Brewers Restaurant Micro-Brewery"|"Toronto" "Amsterdam Brewing Co."|"Toronto" "Ball Brewing Company Ltd."|"Toronto" "Big Ram Brewing Company"|"Toronto" "Black Creek Historic Brewery"|"Toronto" "Black Oak Brewing"|"Toronto" "C'est What?"|"Toronto" "Cool Beer Brewing Company"|"Toronto" "Denison's Brewing"|"Toronto" "Duggan's Brewery"|"Toronto" "Feathers"|"Toronto" "Fermentations! - Danforth"|"Toronto" "Fermentations! - Mount Pleasant"|"Toronto" "Granite Brewery & Restaurant"|"Toronto" "Labatt's Breweries of Canada"|"Toronto" "Mill Street Brew Pub"|"Toronto" "Mill Street Brewery"|"Toronto" "Molson Breweries of Canada"|"Toronto" "Molson Brewery at Air Canada Centre"|"Toronto" "Pioneer Brewery Ltd."|"Toronto" "Post-Production Bistro"|"Toronto" "Rotterdam Brewing"|"Toronto" "Steam Whistle Brewing"|"Toronto" "Strand Brasserie"|"Toronto" "Upper Canada Brewing"|"Toronto" JUST what I wanted And One Last Thing Speaking of export, sometimes I want to send data to Excel. And sometimes I want to send multiple objects to Excel – to a single Excel file that is. In version 3.2.1 you can now do that. Let’s export the bulk of the HR schema to Excel, with each table going to it’s own workbook in the same worksheet. Select many tables, put them in in a single Excel worksheet If you try this in previous versions of SQL Developer it will just write the first table to the Excel file. This is one of the bugs we addressed in v3.2.1. Here is what the output Excel file looks like now: Many tables - Many workbooks in an Excel Worksheet I have a sneaky suspicion that this will be a frequently used feature going forward. Excel seems to be the cornerstone of many of our popular features. Imagine that!

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• Why lock-free data structures just aren't lock-free enough

  - by Alex.Davies

  Today's post will explore why the current ways to communicate between threads don't scale, and show you a possible way to build scalable parallel programming on top of shared memory. The problem with shared memory Soon, we will have dozens, hundreds and then millions of cores in our computers. It's inevitable, because individual cores just can't get much faster. At some point, that's going to mean that we have to rethink our architecture entirely, as millions of cores can't all access a shared memory space efficiently. But millions of cores are still a long way off, and in the meantime we'll see machines with dozens of cores, struggling with shared memory. Alex's tip: The best way for an application to make use of that increasing parallel power is to use a concurrency model like actors, that deals with synchronisation issues for you. Then, the maintainer of the actors framework can find the most efficient way to coordinate access to shared memory to allow your actors to pass messages to each other efficiently. At the moment, NAct uses the .NET thread pool and a few locks to marshal messages. It works well on dual and quad core machines, but it won't scale to more cores. Every time we use a lock, our core performs an atomic memory operation (eg. CAS) on a cell of memory representing the lock, so it's sure that no other core can possibly have that lock. This is very fast when the lock isn't contended, but we need to notify all the other cores, in case they held the cell of memory in a cache. As the number of cores increases, the total cost of a lock increases linearly. A lot of work has been done on "lock-free" data structures, which avoid locks by using atomic memory operations directly. These give fairly dramatic performance improvements, particularly on systems with a few (2 to 4) cores. The .NET 4 concurrent collections in System.Collections.Concurrent are mostly lock-free. However, lock-free data structures still don't scale indefinitely, because any use of an atomic memory operation still involves every core in the system. A sync-free data structure Some concurrent data structures are possible to write in a completely synchronization-free way, without using any atomic memory operations. One useful example is a single producer, single consumer (SPSC) queue. It's easy to write a sync-free fixed size SPSC queue using a circular buffer*. Slightly trickier is a queue that grows as needed. You can use a linked list to represent the queue, but if you leave the nodes to be garbage collected once you're done with them, the GC will need to involve all the cores in collecting the finished nodes. Instead, I've implemented a proof of concept inspired by this intel article which reuses the nodes by putting them in a second queue to send back to the producer. * In all these cases, you need to use memory barriers correctly, but these are local to a core, so don't have the same scalability problems as atomic memory operations. Performance tests I tried benchmarking my SPSC queue against the .NET ConcurrentQueue, and against a standard Queue protected by locks. In some ways, this isn't a fair comparison, because both of these support multiple producers and multiple consumers, but I'll come to that later. I started on my dual-core laptop, running a simple test that had one thread producing 64 bit integers, and another consuming them, to measure the pure overhead of the queue. So, nothing very interesting here. Both concurrent collections perform better than the lock-based one as expected, but there's not a lot to choose between the ConcurrentQueue and my SPSC queue. I was a little disappointed, but then, the .NET Framework team spent a lot longer optimising it than I did. So I dug out a more powerful machine that Red Gate's DBA tools team had been using for testing. It is a 6 core Intel i7 machine with hyperthreading, adding up to 12 logical cores. Now the results get more interesting. As I increased the number of producer-consumer pairs to 6 (to saturate all 12 logical cores), the locking approach was slow, and got even slower, as you'd expect. What I didn't expect to be so clear was the drop-off in performance of the lock-free ConcurrentQueue. I could see the machine only using about 20% of available CPU cycles when it should have been saturated. My interpretation is that as all the cores used atomic memory operations to safely access the queue, they ended up spending most of the time notifying each other about cache lines that need invalidating. The sync-free approach scaled perfectly, despite still working via shared memory, which after all, should still be a bottleneck. I can't quite believe that the results are so clear, so if you can think of any other effects that might cause them, please comment! Obviously, this benchmark isn't realistic because we're only measuring the overhead of the queue. Any real workload, even on a machine with 12 cores, would dwarf the overhead, and there'd be no point worrying about this effect. But would that be true on a machine with 100 cores? Still to be solved. The trouble is, you can't build many concurrent algorithms using only an SPSC queue to communicate. In particular, I can't see a way to build something as general purpose as actors on top of just SPSC queues. Fundamentally, an actor needs to be able to receive messages from multiple other actors, which seems to need an MPSC queue. I've been thinking about ways to build a sync-free MPSC queue out of multiple SPSC queues and some kind of sign-up mechanism. Hopefully I'll have something to tell you about soon, but leave a comment if you have any ideas.

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• Talend Enterprise Data Integration overperforms on Oracle SPARC T4

  - by Amir Javanshir

  The SPARC T microprocessor, released in 2005 by Sun Microsystems, and now continued at Oracle, has a good track record in parallel execution and multi-threaded performance. However it was less suited for pure single-threaded workloads. The new SPARC T4 processor is now filling that gap by offering a 5x better single-thread performance over previous generations. Following our long-term relationship with Talend, a fast growing ISV positioned by Gartner in the “Visionaries” quadrant of the “Magic Quadrant for Data Integration Tools”, we decided to test some of their integration components with the T4 chip, more precisely on a T4-1 system, in order to verify first hand if this new processor stands up to its promises. Several tests were performed, mainly focused on: Single-thread performance of the new SPARC T4 processor compared to an older SPARC T2+ processor Overall throughput of the SPARC T4-1 server using multiple threads The tests consisted in reading large amounts of data --ten's of gigabytes--, processing and writing them back to a file or an Oracle 11gR2 database table. They are CPU, memory and IO bound tests. Given the main focus of this project --CPU performance--, bottlenecks were removed as much as possible on the memory and IO sub-systems. When possible, the data to process was put into the ZFS filesystem cache, for instance. Also, two external storage devices were directly attached to the servers under test, each one divided in two ZFS pools for read and write operations. Multi-thread: Testing throughput on the Oracle T4-1 The tests were performed with different number of simultaneous threads (1, 2, 4, 8, 12, 16, 32, 48 and 64) and using different storage devices: Flash, Fibre Channel storage, two stripped internal disks and one single internal disk. All storage devices used ZFS as filesystem and volume management. Each thread read a dedicated 1GB-large file containing 12.5M lines with the following structure: customerID;FirstName;LastName;StreetAddress;City;State;Zip;Cust_Status;Since_DT;Status_DT 1;Ronald;Reagan;South Highway;Santa Fe;Montana;98756;A;04-06-2006;09-08-2008 2;Theodore;Roosevelt;Timberlane Drive;Columbus;Louisiana;75677;A;10-05-2009;27-05-2008 3;Andrew;Madison;S Rustle St;Santa Fe;Arkansas;75677;A;29-04-2005;09-02-2008 4;Dwight;Adams;South Roosevelt Drive;Baton Rouge;Vermont;75677;A;15-02-2004;26-01-2007 […] The following graphs present the results of our tests: Unsurprisingly up to 16 threads, all files fit in the ZFS cache a.k.a L2ARC : once the cache is hot there is no performance difference depending on the underlying storage. From 16 threads upwards however, it is clear that IO becomes a bottleneck, having a good IO subsystem is thus key. Single-disk performance collapses whereas the Sun F5100 and ST6180 arrays allow the T4-1 to scale quite seamlessly. From 32 to 64 threads, the performance is almost constant with just a slow decline. For the database load tests, only the best IO configuration --using external storage devices-- were used, hosting the Oracle table spaces and redo log files. Using the Sun Storage F5100 array allows the T4-1 server to scale up to 48 parallel JVM processes before saturating the CPU. The final result is a staggering 646K lines per second insertion in an Oracle table using 48 parallel threads. Single-thread: Testing the single thread performance Seven different tests were performed on both servers. Given the fact that only one thread, thus one file was read, no IO bottleneck was involved, all data being served from the ZFS cache. Read File ? Filter ? Write File: Read file, filter data, write the filtered data in a new file. The filter is set on the “Status” column: only lines with status set to “A” are selected. This limits each output file to about 500 MB. Read File ? Load Database Table: Read file, insert into a single Oracle table. Average: Read file, compute the average of a numeric column, write the result in a new file. Division & Square Root: Read file, perform a division and square root on a numeric column, write the result data in a new file. Oracle DB Dump: Dump the content of an Oracle table (12.5M rows) into a CSV file. Transform: Read file, transform, write the result data in a new file. The transformations applied are: set the address column to upper case and add an extra column at the end, which is the concatenation of two columns. Sort: Read file, sort a numeric and alpha numeric column, write the result data in a new file. The following table and graph present the final results of the tests: Throughput unit is thousand lines per second processed (K lines/second). Improvement is the % of improvement between the T5140 and T4-1. Test T4-1 (Time s.) T5140 (Time s.) Improvement T4-1 (Throughput) T5140 (Throughput) Read/Filter/Write 125 806 645% 100 16 Read/Load Database 195 1111 570% 64 11 Average 96 557 580% 130 22 Division & Square Root 161 1054 655% 78 12 Oracle DB Dump 164 945 576% 76 13 Transform 159 1124 707% 79 11 Sort 251 1336 532% 50 9 The improvement of single-thread performance is quite dramatic: depending on the tests, the T4 is between 5.4 to 7 times faster than the T2+. It seems clear that the SPARC T4 processor has gone a long way filling the gap in single-thread performance, without sacrifying the multi-threaded capability as it still shows a very impressive scaling on heavy-duty multi-threaded jobs. Finally, as always at Oracle ISV Engineering, we are happy to help our ISV partners test their own applications on our platforms, so don't hesitate to contact us and let's see what the SPARC T4-based systems can do for your application! "As describe in this benchmark, Talend Enterprise Data Integration has overperformed on T4. I was generally happy to see that the T4 gave scaling opportunities for many scenarios like complex aggregations. Row by row insertion in Oracle DB is faster with more than 650,000 rows per seconds without using any bulk Oracle capabilities !" Cedric Carbone, Talend CTO.

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• MySQL Connect 9 Days Away – Optimizer Sessions

  - by Bertrand Matthelié

  72 1024x768 Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Following my previous blog post focusing on InnoDB talks at MySQL Connect, let us review today the sessions focusing on the MySQL Optimizer: Saturday, 11.30 am, Room Golden Gate 6: MySQL Optimizer Overview—Olav Sanstå, Oracle The goal of MySQL optimizer is to take a SQL query as input and produce an optimal execution plan for the query. This session presents an overview of the main phases of the MySQL optimizer and the primary optimizations done to the query. These optimizations are based on a combination of logical transformations and cost-based decisions. Examples of optimization strategies the presentation covers are the main query transformations, the join optimizer, the data access selection strategies, and the range optimizer. For the cost-based optimizations, an overview of the cost model and the data used for doing the cost estimations is included. Saturday, 1.00 pm, Room Golden Gate 6: Overview of New Optimizer Features in MySQL 5.6—Manyi Lu, Oracle Many optimizer features have been added into MySQL 5.6. This session provides an introduction to these great features. Multirange read, index condition pushdown, and batched key access will yield huge performance improvements on large data volumes. Structured explain, explain for update/delete/insert, and optimizer tracing will help users analyze and speed up queries. And last but not least, the session covers subquery optimizations in Release 5.6. Saturday, 7.00 pm, Room Golden Gate 4: BoF: Query Optimizations: What Is New and What Is Coming? This BoF presents common techniques for query optimization, covers what is new in MySQL 5.6, and provides a discussion forum in which attendees can tell the MySQL optimizer team which optimizations they would like to see in the future. Sunday, 1.15 pm, Room Golden Gate 8: Query Performance Comparison of MySQL 5.5 and MySQL 5.6—Øystein Grøvlen, Oracle MySQL Release 5.6 contains several improvements in the query optimizer that create improved performance for complex queries. This presentation looks at how MySQL 5.6 improves the performance of many of the queries in the DBT-3 benchmark. Based on the observed improvements, the presentation discusses what makes the specific queries perform better in Release 5.6. It describes the relevant new optimization techniques and gives examples of the types of queries that will benefit from these techniques. Sunday, 4.15 pm, Room Golden Gate 4: Powerful EXPLAIN in MySQL 5.6—Evgeny Potemkin, Oracle The EXPLAIN command of MySQL has long been a very useful tool for understanding how MySQL will execute a query. Release 5.6 of the MySQL database offers several new additions that give more-detailed information about the query plan and make it easier to understand at the same time. This presentation gives an overview of new EXPLAIN features: structured EXPLAIN in JSON format, EXPLAIN for INSERT/UPDATE/DELETE, and optimizer tracing. Examples in the session give insights into how you can take advantage of the new features. They show how these features supplement and relate to each other and to classical EXPLAIN and how and why the MySQL server chooses a particular query plan. You can check out the full program here as well as in the September edition of the MySQL newsletter. Not registered yet? You can still save US$ 300 over the on-site fee – Register Now!

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• How do I prove or disprove "god" objects are wrong?

  - by honestduane

  Problem Summary: Long story short, I inherited a code base and an development team I am not allowed to replace and the use of God Objects is a big issue. Going forward, I want to have us re-factor things but I am getting push-back from the teams who want to do everything with God Objects "because its easier" and this means I would not be allowed to re-factor. I pushed back citing my years of dev experience, that I'm the new boss who was hired to know these things, etc, and so did the third party offshore companies account sales rep, and this is now at the executive level and my meeting is tomorrow and I want to go in with a lot of technical ammo to advocate best practices because I feel it will be cheaper in the long run (And I personally feel that is what the third party is worried about) for the company. My issue is from a technical level, I know its good long term but I'm having trouble with the ultra short term and 6 months term, and while its something I "know" I cant prove it with references and cited resources outside of one person (Robert C. Martin, aka Uncle Bob), as that is what I am being asked to do as I have been told having data from one person and only one person (Robert C Martin) is not good enough of an argument. Question: What are some resources I can cite directly (Title, year published, page number, quote) by well known experts in the field that explicitly say this use of "God" Objects/Classes/Systems is bad (or good, since we are looking for the most technically valid solution)? Research I have already done: I have a number of books here and I have searched their indexes for the use of the words "god object" and "god class". I found that oddly its almost never used and the copy of the GoF book I have for example, never uses it (At least according to the index in front of me) but I have found it in 2 books per the below, but I want more I can use. I checked the Wikipedia page for "God Object" and its currently a stub with little reference links so although I personally agree with that it says, It doesn't have much I can use in an environment where personal experience is not considered valid. The book cited is also considered too old to be valid by the people I am debating these technical points with as the argument they are making is that "it was once thought to be bad but nobody could prove it, and now modern software says "god" objects are good to use". I personally believe that this statement is incorrect, but I want to prove the truth, whatever it is. In Robert C Martin's "Agile Principles, Patterns, and Practices in C#" (ISBN: 0-13-185725-8, hardcover) where on page 266 it states "Everybody knows that god classes are a bad idea. We don't want to concentrate all the intelligence of a system into a single object or a single function. One of the goals of OOD is the partitioning and distribution of behavior into many classes and many function." -- And then goes on to say sometimes its better to use God Classes anyway sometimes (Citing micro-controllers as an example). In Robert C Martin's "Clean Code: A Handbook of Agile Software Craftsmanship" page 136 (And only this page) talks about the "God class" and calls it out as a prime example of a violation of the "classes should be small" rule he uses to promote the Single Responsibility Principle" starting on on page 138. The problem I have is all my references and citations come from the same person (Robert C. Martin), and am from the same single person/source. I am being told that because he is just one guy, my desire to not use "God Classes" is invalid and not accepted as a standard best practice in the software industry. Is this true? Am I doing things wrong from a technical perspective by trying to keep to the teaching of Uncle Bob? God Objects and Object Oriented Programming and Design: The more I think of this the more I think this is more something you learn when you study OOP and its never explicitly called out; Its implicit to good design is my thinking (Feel free to correct me, please, as I want to learn), The problem is I "know" this, but but not everybody does, so in this case its not considered a valid argument because I am effectively calling it out as universal truth when in fact most people are statistically ignorant of it since statistically most people are not programmers. Conclusion: I am at a loss on what to search for to get the best additional results to cite, since they are making a technical claim and I want to know the truth and be able to prove it with citations like a real engineer/scientist, even if I am biased against god objects due to my personal experience with code that used them. Any assistance or citations would be deeply appreciated.

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• .NET 4: &ldquo;Slim&rdquo;-style performance boost!

  - by Vitus

  RTM version of .NET 4 and Visual Studio 2010 is available, and now we can do some test with it. Parallel Extensions is one of the most valuable part of .NET 4.0. It’s a set of good tools for easily consuming multicore hardware power. And it also contains some “upgraded” sync primitives – Slim-version. For example, it include updated variant of widely known ManualResetEvent. For people, who don’t know about it: you can sync concurrency execution of some pieces of code with this sync primitive. Instance of ManualResetEvent can be in 2 states: signaled and non-signaled. Transition between it possible by Set() and Reset() methods call. Some shortly explanation: Thread 1 Thread 2 Time mre.Reset(); mre.WaitOne(); //code execution 0 //wating //code execution 1 //wating //code execution 2 //wating //code execution 3 //wating mre.Set(); 4 //code execution //… 5 Upgraded version of this primitive is ManualResetEventSlim. The idea in decreasing performance cost in case, when only 1 thread use it. Main concept in the “hybrid sync schema”, which can be done as following:   internal sealed class SimpleHybridLock : IDisposable { private Int32 m_waiters = 0; private AutoResetEvent m_waiterLock = new AutoResetEvent(false);   public void Enter() { if (Interlocked.Increment(ref m_waiters) == 1) return; m_waiterLock.WaitOne(); }   public void Leave() { if (Interlocked.Decrement(ref m_waiters) == 0) return; m_waiterLock.Set(); }   public void Dispose() { m_waiterLock.Dispose(); } } It’s a sample from Jeffry Richter’s book “CLR via C#”, 3rd edition. Primitive SimpleHybridLock have two public methods: Enter() and Leave(). You can put your concurrency-critical code between calls of these methods, and it would executed in only one thread at the moment. Code is really simple: first thread, called Enter(), increase counter. Second thread also increase counter, and suspend while m_waiterLock is not signaled. So, if we don’t have concurrent access to our lock, “heavy” methods WaitOne() and Set() will not called. It’s can give some performance bonus. ManualResetEvent use the similar idea. Of course, it have more “smart” technics inside, like a checking of recursive calls, and so on. I want to know a real difference between classic ManualResetEvent realization, and new –Slim. I wrote a simple “benchmark”: class Program { static void Main(string[] args) { ManualResetEventSlim mres = new ManualResetEventSlim(false); ManualResetEventSlim mres2 = new ManualResetEventSlim(false);   ManualResetEvent mre = new ManualResetEvent(false);   long total = 0; int COUNT = 50;   for (int i = 0; i < COUNT; i++) { mres2.Reset(); Stopwatch sw = Stopwatch.StartNew();   ThreadPool.QueueUserWorkItem((obj) => { //Method(mres, true); Method2(mre, true); mres2.Set(); }); //Method(mres, false); Method2(mre, false);   mres2.Wait(); sw.Stop();   Console.WriteLine("Pass {0}: {1} ms", i, sw.ElapsedMilliseconds); total += sw.ElapsedMilliseconds; }   Console.WriteLine(); Console.WriteLine("==============================="); Console.WriteLine("Done in average=" + total / (double)COUNT); Console.ReadLine(); }   private static void Method(ManualResetEventSlim mre, bool value) { for (int i = 0; i < 9000000; i++) { if (value) { mre.Set(); } else { mre.Reset(); } } }   private static void Method2(ManualResetEvent mre, bool value) { for (int i = 0; i < 9000000; i++) { if (value) { mre.Set(); } else { mre.Reset(); } } } } I use 2 concurrent thread (the main thread and one from thread pool) for setting and resetting ManualResetEvents, and try to run test COUNT times, and calculate average execution time. Here is the results (I get it on my dual core notebook with T7250 CPU and Windows 7 x64): ManualResetEvent ManualResetEventSlim Difference is obvious and serious – in 10 times! So, I think preferable way is using ManualResetEventSlim, because not always on calling Set() and Reset() will be called “heavy” methods for working with Windows kernel-mode objects. It’s a small and nice improvement! ;)

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• How to Tell If Your Computer is Overheating and What to Do About It

  - by Chris Hoffman

  Heat is a computer’s enemy. Computers are designed with heat dispersion and ventilation in mind so they don’t overheat. If too much heat builds up, your computer may become unstable or suddenly shut down. The CPU and graphics card produce much more heat when running demanding applications. If there’s a problem with your computer’s cooling system, an excess of heat could even physically damage its components. Is Your Computer Overheating? When using a typical computer in a typical way, you shouldn’t have to worry about overheating at all. However, if you’re encountering system instability issues like abrupt shut downs, blue screens, and freezes — especially while doing something demanding like playing PC games or encoding video — your computer may be overheating. This can happen for several reasons. Your computer’s case may be full of dust, a fan may have failed, something may be blocking your computer’s vents, or you may have a compact laptop that was never designed to run at maximum performance for hours on end. Monitoring Your Computer’s Temperature First, bear in mind that different CPUs and GPUs (graphics cards) have different optimal temperature ranges. Before getting too worried about a temperature, be sure to check your computer’s documentation — or its CPU or graphics card specifications — and ensure you know the temperature ranges your hardware can handle. You can monitor your computer’s temperatures in a variety of different ways. First, you may have a way to monitor temperature that is already built into your system. You can often view temperature values in your computer’s BIOS or UEFI settings screen. This allows you to quickly see your computer’s temperature if Windows freezes or blue screens on you — just boot the computer, enter the BIOS or UEFI screen, and check the temperatures displayed there. Note that not all BIOSes or UEFI screens will display this information, but it is very common. There are also programs that will display your computer’s temperature. Such programs just read the sensors inside your computer and show you the temperature value they report, so there are a wide variety of tools you can use for this, from the simple Speccy system information utility to an advanced tool like SpeedFan. HWMonitor also offer this feature, displaying a wide variety of sensor information. Be sure to look at your CPU and graphics card temperatures. You can also find other temperatures, such as the temperature of your hard drive, but these components will generally only overheat if it becomes extremely hot in the computer’s case. They shouldn’t generate too much heat on their own. If you think your computer may be overheating, don’t just glance as these sensors once and ignore them. Do something demanding with your computer, such as running a CPU burn-in test with Prime 95, playing a PC game, or running a graphical benchmark. Monitor the computer’s temperature while you do this, even checking a few hours later — does any component overheat after you push it hard for a while? Preventing Your Computer From Overheating If your computer is overheating, here are some things you can do about it: Dust Out Your Computer’s Case: Dust accumulates in desktop PC cases and even laptops over time, clogging fans and blocking air flow. This dust can cause ventilation problems, trapping heat and preventing your PC from cooling itself properly. Be sure to clean your computer’s case occasionally to prevent dust build-up. Unfortunately, it’s often more difficult to dust out overheating laptops. Ensure Proper Ventilation: Put the computer in a location where it can properly ventilate itself. If it’s a desktop, don’t push the case up against a wall so that the computer’s vents become blocked or leave it near a radiator or heating vent. If it’s a laptop, be careful to not block its air vents, particularly when doing something demanding. For example, putting a laptop down on a mattress, allowing it to sink in, and leaving it there can lead to overheating — especially if the laptop is doing something demanding and generating heat it can’t get rid of. Check if Fans Are Running: If you’re not sure why your computer started overheating, open its case and check that all the fans are running. It’s possible that a CPU, graphics card, or case fan failed or became unplugged, reducing air flow. Tune Up Heat Sinks: If your CPU is overheating, its heat sink may not be seated correctly or its thermal paste may be old. You may need to remove the heat sink and re-apply new thermal paste before reseating the heat sink properly. This tip applies more to tweakers, overclockers, and people who build their own PCs, especially if they may have made a mistake when originally applying the thermal paste. This is often much more difficult when it comes to laptops, which generally aren’t designed to be user-serviceable. That can lead to trouble if the laptop becomes filled with dust and needs to be cleaned out, especially if the laptop was never designed to be opened by users at all. Consult our guide to diagnosing and fixing an overheating laptop for help with cooling down a hot laptop. Overheating is a definite danger when overclocking your CPU or graphics card. Overclocking will cause your components to run hotter, and the additional heat will cause problems unless you can properly cool your components. If you’ve overclocked your hardware and it has started to overheat — well, throttle back the overclock! Image Credit: Vinni Malek on Flickr     

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• How to make creating viewmodels at runtime less painful

  - by Mr Happy

  I apologize for the long question, it reads a bit as a rant, but I promise it's not! I've summarized my question(s) below In the MVC world, things are straightforward. The Model has state, the View shows the Model, and the Controller does stuff to/with the Model (basically), a controller has no state. To do stuff the Controller has some dependencies on web services, repository, the lot. When you instantiate a controller you care about supplying those dependencies, nothing else. When you execute an action (method on Controller), you use those dependencies to retrieve or update the Model or calling some other domain service. If there's any context, say like some user wants to see the details of a particular item, you pass the Id of that item as parameter to the Action. Nowhere in the Controller is there any reference to any state. So far so good. Enter MVVM. I love WPF, I love data binding. I love frameworks that make data binding to ViewModels even easier (using Caliburn Micro a.t.m.). I feel things are less straightforward in this world though. Let's do the exercise again: the Model has state, the View shows the ViewModel, and the ViewModel does stuff to/with the Model (basically), a ViewModel does have state! (to clarify; maybe it delegates all the properties to one or more Models, but that means it must have a reference to the model one way or another, which is state in itself) To do stuff the ViewModel has some dependencies on web services, repository, the lot. When you instantiate a ViewModel you care about supplying those dependencies, but also the state. And this, ladies and gentlemen, annoys me to no end. Whenever you need to instantiate a ProductDetailsViewModel from the ProductSearchViewModel (from which you called the ProductSearchWebService which in turn returned IEnumerable<ProductDTO>, everybody still with me?), you can do one of these things: call new ProductDetailsViewModel(productDTO, _shoppingCartWebService /* dependcy */);, this is bad, imagine 3 more dependencies, this means the ProductSearchViewModel needs to take on those dependencies as well. Also changing the constructor is painful. call _myInjectedProductDetailsViewModelFactory.Create().Initialize(productDTO);, the factory is just a Func, they are easily generated by most IoC frameworks. I think this is bad because Init methods are a leaky abstraction. You also can't use the readonly keyword for fields that are set in the Init method. I'm sure there are a few more reasons. call _myInjectedProductDetailsViewModelAbstractFactory.Create(productDTO); So... this is the pattern (abstract factory) that is usually recommended for this type of problem. I though it was genius since it satisfies my craving for static typing, until I actually started using it. The amount of boilerplate code is I think too much (you know, apart from the ridiculous variable names I get use). For each ViewModel that needs runtime parameters you'll get two extra files (factory interface and implementation), and you need to type the non-runtime dependencies like 4 extra times. And each time the dependencies change, you get to change it in the factory as well. It feels like I don't even use a DI container anymore. (I think Castle Windsor has some kind of solution for this [with it's own drawbacks, correct me if I'm wrong]). do something with anonymous types or dictionary. I like my static typing. So, yeah. Mixing state and behavior in this way creates a problem which don't exist at all in MVC. And I feel like there currently isn't a really adequate solution for this problem. Now I'd like to observe some things: People actually use MVVM. So they either don't care about all of the above, or they have some brilliant other solution. I haven't found an in-depth example of MVVM with WPF. For example, the NDDD-sample project immensely helped me understand some DDD concepts. I'd really like it if someone could point me in the direction of something similar for MVVM/WPF. Maybe I'm doing MVVM all wrong and I should turn my design upside down. Maybe I shouldn't have this problem at all. Well I know other people have asked the same question so I think I'm not the only one. To summarize Am I correct to conclude that having the ViewModel being an integration point for both state and behavior is the reason for some difficulties with the MVVM pattern as a whole? Is using the abstract factory pattern the only/best way to instantiate a ViewModel in a statically typed way? Is there something like an in depth reference implementation available? Is having a lot of ViewModels with both state/behavior a design smell?

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• Polite busy-waiting with WRPAUSE on SPARC

  - by Dave

  Unbounded busy-waiting is an poor idea for user-space code, so we typically use spin-then-block strategies when, say, waiting for a lock to be released or some other event. If we're going to spin, even briefly, then we'd prefer to do so in a manner that minimizes performance degradation for other sibling logical processors ("strands") that share compute resources. We want to spin politely and refrain from impeding the progress and performance of other threads — ostensibly doing useful work and making progress — that run on the same core. On a SPARC T4, for instance, 8 strands will share a core, and that core has its own L1 cache and 2 pipelines. On x86 we have the PAUSE instruction, which, naively, can be thought of as a hardware "yield" operator which temporarily surrenders compute resources to threads on sibling strands. Of course this helps avoid intra-core performance interference. On the SPARC T2 our preferred busy-waiting idiom was "RD %CCR,%G0" which is a high-latency no-nop. The T4 provides a dedicated and extremely useful WRPAUSE instruction. The processor architecture manuals are the authoritative source, but briefly, WRPAUSE writes a cycle count into the the PAUSE register, which is ASR27. Barring interrupts, the processor then delays for the requested period. There's no need for the operating system to save the PAUSE register over context switches as it always resets to 0 on traps. Digressing briefly, if you use unbounded spinning then ultimately the kernel will preempt and deschedule your thread if there are other ready threads than are starving. But by using a spin-then-block strategy we can allow other ready threads to run without resorting to involuntary time-slicing, which operates on a long-ish time scale. Generally, that makes your application more responsive. In addition, by blocking voluntarily we give the operating system far more latitude regarding power management. Finally, I should note that while we have OS-level facilities like sched_yield() at our disposal, yielding almost never does what you'd want or naively expect. Returning to WRPAUSE, it's natural to ask how well it works. To help answer that question I wrote a very simple C/pthreads benchmark that launches 8 concurrent threads and binds those threads to processors 0..7. The processors are numbered geographically on the T4, so those threads will all be running on just one core. Unlike the SPARC T2, where logical CPUs 0,1,2 and 3 were assigned to the first pipeline, and CPUs 4,5,6 and 7 were assigned to the 2nd, there's no fixed mapping between CPUs and pipelines in the T4. And in some circumstances when the other 7 logical processors are idling quietly, it's possible for the remaining logical processor to leverage both pipelines. Some number T of the threads will iterate in a tight loop advancing a simple Marsaglia xor-shift pseudo-random number generator. T is a command-line argument. The main thread loops, reporting the aggregate number of PRNG steps performed collectively by those T threads in the last 10 second measurement interval. The other threads (there are 8-T of these) run in a loop busy-waiting concurrently with the T threads. We vary T between 1 and 8 threads, and report on various busy-waiting idioms. The values in the table are the aggregate number of PRNG steps completed by the set of T threads. The unit is millions of iterations per 10 seconds. For the "PRNG step" busy-waiting mode, the busy-waiting threads execute exactly the same code as the T worker threads. We can easily compute the average rate of progress for individual worker threads by dividing the aggregate score by the number of worker threads T. I should note that the PRNG steps are extremely cycle-heavy and access almost no memory, so arguably this microbenchmark is not as representative of "normal" code as it could be. And for the purposes of comparison I included a row in the table that reflects a waiting policy where the waiting threads call poll(NULL,0,1000) and block in the kernel. Obviously this isn't busy-waiting, but the data is interesting for reference. _table { border:2px black dotted; margin: auto; width: auto; } _tr { border: 2px red dashed; } _td { border: 1px green solid; } _table { border:2px black dotted; margin: auto; width: auto; } _tr { border: 2px red dashed; } td { background-color : #E0E0E0 ; text-align : right ; } th { text-align : left ; } td { background-color : #E0E0E0 ; text-align : right ; } th { text-align : left ; } Aggregate progress T = #worker threads Wait Mechanism for 8-T threadsT=1T=2T=3T=4T=5T=6T=7T=8 Park thread in poll() 32653347334833483348334833483348 no-op 415 831 124316482060249729303349 RD %ccr,%g0 "pause" 14262429269228623013316232553349 PRNG step 412 829 124616702092251029303348 WRPause(8000) 32443361333133483349334833483348 WRPause(4000) 32153308331533223347334833473348 WRPause(1000) 30853199322432513310334833483348 WRPause(500) 29173070315032223270330933483348 WRPause(250) 26942864294930773205338833483348 WRPause(100) 21552469262227902911321433303348

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• MVVM - how to make creating viewmodels at runtime less painfull

  - by Mr Happy

  I apologize for the long question, it reads a bit as a rant, but I promise it's not! I've summarized my question(s) below In the MVC world, things are straightforward. The Model has state, the View shows the Model, and the Controller does stuff to/with the Model (basically), a controller has no state. To do stuff the Controller has some dependencies on web services, repository, the lot. When you instantiate a controller you care about supplying those dependencies, nothing else. When you execute an action (method on Controller), you use those dependencies to retrieve or update the Model or calling some other domain service. If there's any context, say like some user wants to see the details of a particular item, you pass the Id of that item as parameter to the Action. Nowhere in the Controller is there any reference to any state. So far so good. Enter MVVM. I love WPF, I love data binding. I love frameworks that make data binding to ViewModels even easier (using Caliburn Micro a.t.m.). I feel things are less straightforward in this world though. Let's do the exercise again: the Model has state, the View shows the ViewModel, and the ViewModel does stuff to/with the Model (basically), a ViewModel does have state! (to clarify; maybe it delegates all the properties to one or more Models, but that means it must have a reference to the model one way or another, which is state in itself) To do stuff the ViewModel has some dependencies on web services, repository, the lot. When you instantiate a ViewModel you care about supplying those dependencies, but also the state. And this, ladies and gentlemen, annoys me to no end. Whenever you need to instantiate a ProductDetailsViewModel from the ProductSearchViewModel (from which you called the ProductSearchWebService which in turn returned IEnumerable<ProductDTO>, everybody still with me?), you can do one of these things: call new ProductDetailsViewModel(productDTO, _shoppingCartWebService /* dependcy */);, this is bad, imagine 3 more dependencies, this means the ProductSearchViewModel needs to take on those dependencies as well. Also changing the constructor is painfull. call _myInjectedProductDetailsViewModelFactory.Create().Initialize(productDTO);, the factory is just a Func, they are easily generated by most IoC frameworks. I think this is bad because Init methods are a leaky abstraction. You also can't use the readonly keyword for fields that are set in the Init method. I'm sure there are a few more reasons. call _myInjectedProductDetailsViewModelAbstractFactory.Create(productDTO); So... this is the pattern (abstract factory) that is usually recommended for this type of problem. I though it was genious since it satisfies my craving for static typing, until I actually started using it. The amount of boilerplate code is I think too much (you know, apart from the ridiculous variable names I get use). For each ViewModel that needs runtime parameters you'll get two extra files (factory interface and implementation), and you need to type the non-runtime dependencies like 4 extra times. And each time the dependencies change, you get to change it in the factory as well. It feels like I don't even use an DI container anymore. (I think Castle Windsor has some kind of solution for this [with it's own drawbacks, correct me if I'm wrong]). do something with anonymous types or dictionary. I like my static typing. So, yeah. Mixing state and behavior in this way creates a problem which don't exist at all in MVC. And I feel like there currently isn't a really adequate solution for this problem. Now I'd like to observe some things: People actually use MVVM. So they either don't care about all of the above, or they have some brilliant other solution. I haven't found an indepth example of MVVM with WPF. For example, the NDDD-sample project immensely helped me understand some DDD concepts. I'd really like it if someone could point me in the direction of something similar for MVVM/WPF. Maybe I'm doing MVVM all wrong and I should turn my design upside down. Maybe I shouldn't have this problem at all. Well I know other people have asked the same question so I think I'm not the only one. To summarize Am I correct to conclude that having the ViewModel being an integration point for both state and behavior is the reason for some difficulties with the MVVM pattern as a whole? Is using the abstract factory pattern the only/best way to instantiate a ViewModel in a statically typed way? Is there something like an in depth reference implementation available? Is having a lot of ViewModels with both state/behavior a design smell?

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• Oracle NoSQL Database Exceeds 1 Million Mixed YCSB Ops/Sec

  - by Charles Lamb

  We ran a set of YCSB performance tests on Oracle NoSQL Database using SSD cards and Intel Xeon E5-2690 CPUs with the goal of achieving 1M mixed ops/sec on a 95% read / 5% update workload. We used the standard YCSB parameters: 13 byte keys and 1KB data size (1,102 bytes after serialization). The maximum database size was 2 billion records, or approximately 2 TB of data. We sized the shards to ensure that this was not an "in-memory" test (i.e. the data portion of the B-Trees did not fit into memory). All updates were durable and used the "simple majority" replica ack policy, effectively 'committing to the network'. All read operations used the Consistency.NONE_REQUIRED parameter allowing reads to be performed on any replica. In the past we have achieved 100K ops/sec using SSD cards on a single shard cluster (replication factor 3) so for this test we used 10 shards on 15 Storage Nodes with each SN carrying 2 Rep Nodes and each RN assigned to its own SSD card. After correcting a scaling problem in YCSB, we blew past the 1M ops/sec mark with 8 shards and proceeded to hit 1.2M ops/sec with 10 shards.  Hardware Configuration We used 15 servers, each configured with two 335 GB SSD cards. We did not have homogeneous CPUs across all 15 servers available to us so 12 of the 15 were Xeon E5-2690, 2.9 GHz, 2 sockets, 32 threads, 193 GB RAM, and the other 3 were Xeon E5-2680, 2.7 GHz, 2 sockets, 32 threads, 193 GB RAM.  There might have been some upside in having all 15 machines configured with the faster CPU, but since CPU was not the limiting factor we don't believe the improvement would be significant. The client machines were Xeon X5670, 2.93 GHz, 2 sockets, 24 threads, 96 GB RAM. Although the clients had 96 GB of RAM, neither the NoSQL Database or YCSB clients require anywhere near that amount of memory and the test could have just easily been run with much less. Networking was all 10GigE. YCSB Scaling Problem We made three modifications to the YCSB benchmark. The first was to allow the test to accommodate more than 2 billion records (effectively int's vs long's). To keep the key size constant, we changed the code to use base 32 for the user ids. The second change involved to the way we run the YCSB client in order to make the test itself horizontally scalable.The basic problem has to do with the way the YCSB test creates its Zipfian distribution of keys which is intended to model "real" loads by generating clusters of key collisions. Unfortunately, the percentage of collisions on the most contentious keys remains the same even as the number of keys in the database increases. As we scale up the load, the number of collisions on those keys increases as well, eventually exceeding the capacity of the single server used for a given key.This is not a workload that is realistic or amenable to horizontal scaling. YCSB does provide alternate key distribution algorithms so this is not a shortcoming of YCSB in general. We decided that a better model would be for the key collisions to be limited to a given YCSB client process. That way, as additional YCSB client processes (i.e. additional load) are added, they each maintain the same number of collisions they encounter themselves, but do not increase the number of collisions on a single key in the entire store. We added client processes proportionally to the number of records in the database (and therefore the number of shards). This change to the use of YCSB better models a use case where new groups of users are likely to access either just their own entries, or entries within their own subgroups, rather than all users showing the same interest in a single global collection of keys. If an application finds every user having the same likelihood of wanting to modify a single global key, that application has no real hope of getting horizontal scaling. Finally, we used read/modify/write (also known as "Compare And Set") style updates during the mixed phase. This uses versioned operations to make sure that no updates are lost. This mode of operation provides better application behavior than the way we have typically run YCSB in the past, and is only practical at scale because we eliminated the shared key collision hotspots.It is also a more realistic testing scenario. To reiterate, all updates used a simple majority replica ack policy making them durable. Scalability Results In the table below, the "KVS Size" column is the number of records with the number of shards and the replication factor. Hence, the first row indicates 400m total records in the NoSQL Database (KV Store), 2 shards, and a replication factor of 3. The "Clients" column indicates the number of YCSB client processes. "Threads" is the number of threads per process with the total number of threads. Hence, 90 threads per YCSB process for a total of 360 threads. The client processes were distributed across 10 client machines. Shards KVS Size Clients Mixed (records) Threads OverallThroughput(ops/sec) Read Latencyav/95%/99%(ms) Write Latencyav/95%/99%(ms) 2 400m(2x3) 4 90(360) 302,152 0.76/1/3 3.08/8/35 4 800m(4x3) 8 90(720) 558,569 0.79/1/4 3.82/16/45 8 1600m(8x3) 16 90(1440) 1,028,868 0.85/2/5 4.29/21/51 10 2000m(10x3) 20 90(1800) 1,244,550 0.88/2/6 4.47/23/53

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• Adjusting server-side tickrate dynamically

  - by Stuart Blackler

  I know nothing of game development/this site, so I apologise if this is completely foobar. Today I experimented with building a small game loop for a network game (think MW3, CSGO etc). I was wondering why they do not build in automatic rate adjustment based on server performance? Would it affect the client that much if the client knew this frame is based on this tickrate? Has anyone attempted this before? Here is what my noobish C++ brain came up with earlier. It will improve the tickrate if it has been stable for x ticks. If it "lags", the tickrate will be reduced down by y amount: // GameEngine.cpp : Defines the entry point for the console application. // #ifdef WIN32 #include <Windows.h> #else #include <sys/time.h> #include <ctime> #endif #include<iostream> #include <dos.h> #include "stdafx.h" using namespace std; UINT64 GetTimeInMs() { #ifdef WIN32 /* Windows */ FILETIME ft; LARGE_INTEGER li; /* Get the amount of 100 nano seconds intervals elapsed since January 1, 1601 (UTC) and copy it * to a LARGE_INTEGER structure. */ GetSystemTimeAsFileTime(&ft); li.LowPart = ft.dwLowDateTime; li.HighPart = ft.dwHighDateTime; UINT64 ret = li.QuadPart; ret -= 116444736000000000LL; /* Convert from file time to UNIX epoch time. */ ret /= 10000; /* From 100 nano seconds (10^-7) to 1 millisecond (10^-3) intervals */ return ret; #else /* Linux */ struct timeval tv; gettimeofday(&tv, NULL); uint64 ret = tv.tv_usec; /* Convert from micro seconds (10^-6) to milliseconds (10^-3) */ ret /= 1000; /* Adds the seconds (10^0) after converting them to milliseconds (10^-3) */ ret += (tv.tv_sec * 1000); return ret; #endif } int _tmain(int argc, _TCHAR* argv[]) { int sv_tickrate_max = 1000; // The maximum amount of ticks per second int sv_tickrate_min = 100; // The minimum amount of ticks per second int sv_tickrate_adjust = 10; // How much to de/increment the tickrate by int sv_tickrate_stable_before_increment = 1000; // How many stable ticks before we increase the tickrate again int sys_tickrate_current = sv_tickrate_max; // Always start at the highest possible tickrate for the best performance int counter_stable_ticks = 0; // How many ticks we have not lagged for UINT64 __startTime = GetTimeInMs(); int ticks = 100000; while(ticks > 0) { int maxTimeInMs = 1000 / sys_tickrate_current; UINT64 _startTime = GetTimeInMs(); // Long code here... cout << "."; UINT64 _timeTaken = GetTimeInMs() - _startTime; if(_timeTaken < maxTimeInMs) { Sleep(maxTimeInMs - _timeTaken); counter_stable_ticks++; if(counter_stable_ticks >= sv_tickrate_stable_before_increment) { // reset the stable # ticks counter counter_stable_ticks = 0; // make sure that we don't go over the maximum tickrate if(sys_tickrate_current + sv_tickrate_adjust <= sv_tickrate_max) { sys_tickrate_current += sv_tickrate_adjust; // let me know in console #DEBUG cout << endl << "Improving tickrate. New tickrate: " << sys_tickrate_current << endl; } } } else if(_timeTaken > maxTimeInMs) { cout << endl; if((sys_tickrate_current - sv_tickrate_adjust) > sv_tickrate_min) { sys_tickrate_current -= sv_tickrate_adjust; } else { if(sys_tickrate_current == sv_tickrate_min) { cout << "Please reduce sv_tickrate_min..." << endl; } else{ sys_tickrate_current = sv_tickrate_min; } } // let me know in console #DEBUG cout << "The server has lag. Reduced tickrate to: " << sys_tickrate_current << endl; } ticks--; } UINT64 __timeTaken = GetTimeInMs() - __startTime; cout << endl << endl << "Total time in ms: " << __timeTaken; cout << endl << "Ending tickrate: " << sys_tickrate_current; char test; cin >> test; return 0; }

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• Why won't USB 3.0 external hard drive run at USB 3.0 speeds?

  - by jgottula

  I recently purchased a PCI Express x1 USB 3.0 controller card (containing the NEC USB 3.0 controller) with the intent of using a USB 3.0 external hard drive with my Linux box. I installed the card in an empty PCIe slot on my motherboard, connected the card to a power cable, strung a USB 3.0 cable between one of the new ports and my external HDD, and connected the HDD to a wall socket for power. Booting the system, the drive works 100% as intended, with the one exception of throughput: rather than using SuperSpeed 4.8 Gbps connectivity, it seems to be falling back to High Speed 480 Mbps USB 2.0-style throughput. Disk Utility shows it as a 480 Mbps device, and running a couple Disk Utility and dd benchmarks confirms that the drive fails to exceed ~40 MB/s (the approximate limit of USB 2.0), despite it being an SSD capable of far more than that. When I connect my USB 3.0 HDD, dmesg shows this: [ 3923.280018] usb 3-2: new high speed USB device using ehci_hcd and address 6 where I would expect to find this: [ 3923.280018] usb 3-2: new SuperSpeed USB device using xhci_hcd and address 6 My system was running on kernel 2.6.35-25-generic at the time. Then, I stumbled upon this forum thread by an individual who found that a bug, which was present in kernels prior to 2.6.37-rc5, could be the culprit for this type of problem. Consequently, I installed the 2.6.37-generic mainline Ubuntu kernel to determine if the problem would go away. It didn't, so I tried 2.6.38-rc3-generic, and even the 2.6.38 nightly from 2010.02.01, to no avail. In short, I'm trying to determine why, with USB 3.0 support in the kernel, my USB 3.0 drive fails to run at full SuperSpeed throughput. See the comments under this question for additional details. Output that might be relevant to the problem (when booting from 2.6.38-rc3): Relevant lines from dmesg: [ 19.589491] xhci_hcd 0000:03:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17 [ 19.589512] xhci_hcd 0000:03:00.0: setting latency timer to 64 [ 19.589516] xhci_hcd 0000:03:00.0: xHCI Host Controller [ 19.589623] xhci_hcd 0000:03:00.0: new USB bus registered, assigned bus number 12 [ 19.650492] xhci_hcd 0000:03:00.0: irq 17, io mem 0xf8100000 [ 19.650556] xhci_hcd 0000:03:00.0: irq 47 for MSI/MSI-X [ 19.650560] xhci_hcd 0000:03:00.0: irq 48 for MSI/MSI-X [ 19.650563] xhci_hcd 0000:03:00.0: irq 49 for MSI/MSI-X [ 19.653946] xHCI xhci_add_endpoint called for root hub [ 19.653948] xHCI xhci_check_bandwidth called for root hub Relevant section of sudo lspci -v: 03:00.0 USB Controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 03) (prog-if 30) Flags: bus master, fast devsel, latency 0, IRQ 17 Memory at f8100000 (64-bit, non-prefetchable) [size=8K] Capabilities: [50] Power Management version 3 Capabilities: [70] MSI: Enable- Count=1/8 Maskable- 64bit+ Capabilities: [90] MSI-X: Enable+ Count=8 Masked- Capabilities: [a0] Express Endpoint, MSI 00 Capabilities: [100] Advanced Error Reporting Capabilities: [140] Device Serial Number ff-ff-ff-ff-ff-ff-ff-ff Capabilities: [150] #18 Kernel driver in use: xhci_hcd Kernel modules: xhci-hcd Relevant section of sudo lsusb -v: Bus 012 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 3.00 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 3 bMaxPacketSize0 9 idVendor 0x1d6b Linux Foundation idProduct 0x0003 3.0 root hub bcdDevice 2.06 iManufacturer 3 Linux 2.6.38-020638rc3-generic xhci_hcd iProduct 2 xHCI Host Controller iSerial 1 0000:03:00.0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0004 1x 4 bytes bInterval 12 Hub Descriptor: bLength 9 bDescriptorType 41 nNbrPorts 4 wHubCharacteristic 0x0009 Per-port power switching Per-port overcurrent protection TT think time 8 FS bits bPwrOn2PwrGood 10 * 2 milli seconds bHubContrCurrent 0 milli Ampere DeviceRemovable 0x00 PortPwrCtrlMask 0xff Hub Port Status: Port 1: 0000.0100 power Port 2: 0000.0100 power Port 3: 0000.0100 power Port 4: 0000.0100 power Device Status: 0x0003 Self Powered Remote Wakeup Enabled Full, non-verbose lsusb: Bus 012 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 011 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 010 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 009 Device 003: ID 04d9:0702 Holtek Semiconductor, Inc. Bus 009 Device 002: ID 046d:c068 Logitech, Inc. G500 Laser Mouse Bus 009 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 008 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 006: ID 174c:5106 ASMedia Technology Inc. Bus 003 Device 004: ID 0bda:0151 Realtek Semiconductor Corp. Mass Storage Device (Multicard Reader) Bus 003 Device 002: ID 058f:6366 Alcor Micro Corp. Multi Flash Reader Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 006: ID 1687:0163 Kingmax Digital Inc. Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 046d:081b Logitech, Inc. Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Full output: full dmesg full lspci full lsusb

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• The Dreaded Startup Repair Loop on Win 7

  - by HighAltitudeCoder

  For most people, upgrading to Windows 7 has been a relatively painless process.  Not me.  I am in the unlucky 1% or less who had a somewhat less pleasant experience.  First, I cloned my entire onto a larger (and much faster) solid state hard drive, only experiencing minimal problems. Then, I bought the Retail version of Windows 7 Ultimate, took a deep breath and... oh yeah, I almost forgot - BACK UP THE COMPUTER.  The next morning I upgraded to Win 7 and everything seemed fine, until... I rebooted the system, the nice Windows 7 launch graphics come up, it's about to launch and AWWW, are you kidding me?!?!  Back to the BIOS splash screen?  Next comes the sequence of failure - attempt repair - unable to repair - do you want to wipe your hard drive decisions. Because I purchased the retail version, a number is provided where I could call Microsoft Tech support.  When I did, they instructed me to click "Install" from my installation CD, which did not work.  When I tried the "Upgrade" option, it reaches an impasse, telling you that yoiu have a newer version of Win 7, and thus cannot Upgrade.  If you choose "Install" you willl lose everything... files, programs, EVERYTHING.  Or at least this is what it tells you.  I was not willing to take the risk. To make things worse, I had installed a new antivirus software application before I realized my system was unstable (Trend Micro Titanium Internet Security), and this was causing additional problems. One interesting thing, and the only saving grace as it turns out, was that my system WOULD successfully reboot into the OS if I chose to restart it, rather than shut it down.  If I chose to shut down, I would have to go through the loop again until I was given the option to restart. As it turned out, I needed to update my BIOS.  I assumed that since I had updated my BIOS a long time ago to settings that were stable under Windows Vista Ultimate x64, I incorrectly expected Win 7 to adopt the same settings and didn't expect there to be any problems.  WRONG. My BIOS had a setting to halt the boot cycle if various kinds of errors were detected.  Windows Vista didn't care about this, but forget it under Windows 7.  I turned immediately corrected that BIOS setting.  Next, there were the two separate BIOS settings: enable USB mouse and enable USB keyboard.  The only sequence of events that would work were to start my reboot process over from stratch with a hard-wired non-usb keyboard and mouse.  Whent the system booted under these settings, it doesn't detect any errors due to either the mouse or keyboard, and actually booted for the first time in a long while (let me tell ya, that's an amazing experience after fiddling with settings for two entire weekends!) Next step: leave your old mouse and keyboard connected, but also connect your other two devices (mouse, keyboard) that use USB connections.  During the boot cycle, the operating system will not fail due to missing requirements during startup, and it will then pick up the new drivers necessary to use your new hardware. If you think you are in the clear here, you are wrong.  The next VERY IMPORTANT step is to remember to change your settings in the BIOS upon next startup.  Specifically, yoiu will need ot change your BIOS to enable USB mouse and enable USB keyboard input.  If you don't, Windows will detect an incompatibility upon the next startup, and you will be stuck once again in the endless cycle of reboot/Startup Repair/reboot/Startup Repair, without ever reaching a successful boot. Here's the thing - the BIOS and the drivers registered in Win 7 need to match.  If they don't, you're going to lose another weekend worrying and fiddling, all the while wondering if you've permanently damaged your hard drive beyond repair. (Sigh).  In the end, things worked out.  I must note that it is saddening to see how many posts there are out there that recommend just doing a clean install, as if it's the only option.  How many countless poor souls have lost their data, their backups, their pictures and videos, all for nothing other than the fact that the person giving advice just didn't know what to do at that point? My advice to you, try having a look at your BIOS settings first and making sure Win 7 can find your BIOS settings, and also disabling in your BIOS anything that might halt your system boot-up process if it encounters errors.

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• How to make creating viewmodels at runtime less painfull

  - by Mr Happy

  I apologize for the long question, it reads a bit as a rant, but I promise it's not! I've summarized my question(s) below In the MVC world, things are straightforward. The Model has state, the View shows the Model, and the Controller does stuff to/with the Model (basically), a controller has no state. To do stuff the Controller has some dependencies on web services, repository, the lot. When you instantiate a controller you care about supplying those dependencies, nothing else. When you execute an action (method on Controller), you use those dependencies to retrieve or update the Model or calling some other domain service. If there's any context, say like some user wants to see the details of a particular item, you pass the Id of that item as parameter to the Action. Nowhere in the Controller is there any reference to any state. So far so good. Enter MVVM. I love WPF, I love data binding. I love frameworks that make data binding to ViewModels even easier (using Caliburn Micro a.t.m.). I feel things are less straightforward in this world though. Let's do the exercise again: the Model has state, the View shows the ViewModel, and the ViewModel does stuff to/with the Model (basically), a ViewModel does have state! (to clarify; maybe it delegates all the properties to one or more Models, but that means it must have a reference to the model one way or another, which is state in itself) To do stuff the ViewModel has some dependencies on web services, repository, the lot. When you instantiate a ViewModel you care about supplying those dependencies, but also the state. And this, ladies and gentlemen, annoys me to no end. Whenever you need to instantiate a ProductDetailsViewModel from the ProductSearchViewModel (from which you called the ProductSearchWebService which in turn returned IEnumerable<ProductDTO>, everybody still with me?), you can do one of these things: call new ProductDetailsViewModel(productDTO, _shoppingCartWebService /* dependcy */);, this is bad, imagine 3 more dependencies, this means the ProductSearchViewModel needs to take on those dependencies as well. Also changing the constructor is painfull. call _myInjectedProductDetailsViewModelFactory.Create().Initialize(productDTO);, the factory is just a Func, they are easily generated by most IoC frameworks. I think this is bad because Init methods are a leaky abstraction. You also can't use the readonly keyword for fields that are set in the Init method. I'm sure there are a few more reasons. call _myInjectedProductDetailsViewModelAbstractFactory.Create(productDTO); So... this is the pattern (abstract factory) that is usually recommended for this type of problem. I though it was genious since it satisfies my craving for static typing, until I actually started using it. The amount of boilerplate code is I think too much (you know, apart from the ridiculous variable names I get use). For each ViewModel that needs runtime parameters you'll get two extra files (factory interface and implementation), and you need to type the non-runtime dependencies like 4 extra times. And each time the dependencies change, you get to change it in the factory as well. It feels like I don't even use an DI container anymore. (I think Castle Windsor has some kind of solution for this [with it's own drawbacks, correct me if I'm wrong]). do something with anonymous types or dictionary. I like my static typing. So, yeah. Mixing state and behavior in this way creates a problem which don't exist at all in MVC. And I feel like there currently isn't a really adequate solution for this problem. Now I'd like to observe some things: People actually use MVVM. So they either don't care about all of the above, or they have some brilliant other solution. I haven't found an indepth example of MVVM with WPF. For example, the NDDD-sample project immensely helped me understand some DDD concepts. I'd really like it if someone could point me in the direction of something similar for MVVM/WPF. Maybe I'm doing MVVM all wrong and I should turn my design upside down. Maybe I shouldn't have this problem at all. Well I know other people have asked the same question so I think I'm not the only one. To summarize Am I correct to conclude that having the ViewModel being an integration point for both state and behavior is the reason for some difficulties with the MVVM pattern as a whole? Is using the abstract factory pattern the only/best way to instantiate a ViewModel in a statically typed way? Is there something like an in depth reference implementation available? Is having a lot of ViewModels with both state/behavior a design smell?

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• Oracle 11g R2 1???????~????????(Exadata??)?????

  - by Yusuke.Yamamoto

  ??2010?11?17???Oracle Database 11g Release2(R2) ???????1???? ????Oracle Database 11g R2 ?????????????????????????? ???? 2010/11/17:????? 2011/01/07:???????(Exadata/??) 2011/01/18:???????(Exadata/?????????????) 2011/02/22:???????(Exadata/?????:IT Leaders ????????) 2011/04/21:?????? 2011/04/21:???????(????????????) 2011/04/21:???????(Exadata/???????????????????????????????????) 2011/06/27:Oracle Exadata Database Machine ????1,000??? ?? Oracle Database 11g R2 ??????? Oracle Database 11g ?????????(????) ??????? Oracle Database 11g R2(???/????) Oracle Database 11g R2 ??????? ?? ??? 2009?11?11? Oracle Exadata Database Machine Version 2 ???? 2009?11?17? Oracle Database 11g R2 ???? 2010?02?01? ?????????????????????????????? 2010?03?31? SAP ? Oracle Database 11g R2 ??????????ISV????????·??????????? 2010?05?18? Windows Server 2008 R2 / Windows 7 ?????????Oracle Database 10g R2 ??? 2010?06?23? Oracle Application Express 4.0 ???? 2010?07?09? ?? Windows RDBMS ?????(2009?)????????? 2010?08?17? TPC-C Benchmark Price/Performance ???????? 2010?09?13? Patch Set 11.2.0.2 for Linux ????(??) 2010?10?20? Oracle Exadata Database Machine X2 ???? 2010?11?17? Oracle Database 11g R2 ????1?? 2010?11?19? ?? Windows RDBMS ?????(2010????)????????????? 2011?03?29? Oracle SQL Developer 3.0 ???? 2011?06?27? Oracle Exadata Database Machine ????1,000????????????????·?????????????? Oracle Database 11g ?????????(????) ????????????????????????????????(????)? ????(??????????) ??????????(???) ????? ????(???) ?????·???????·??? ????? ????·??????·?? ???? ???????(??????????????)|???99.999%???????500???????????? - ITpro ??????????? ????(????) ???(???) ????????(???) ??????(???????????) Oracle Exadata Database Machine ????? Oracle Database 11g ??(????)? ??????????????????????????????????? ????(??????) ????????????? ?????·???????·??? ??(??????????????) ?????(??????????) ?????????(????????) ?????????? ????(???????) ?????? ????/????·???????? ???????????(???????/NTT??????????) ????????????? ???? ???????????? ?????? ??? ?????|DWH?????????????? - IT Leaders(????????)|DWH?????????????? - IT Leaders ????(???????????) Customer Voice ????:????IT?????24??365????????????????????? ?Oracle9i Database ?????????????????????Oracle Database 11g ???????????????????????? Oracle9i Database ???????????????? Customer Voice ??????:Oracle Database 11g????????????????????? ?Oracle ASM ???????????????????I/O????????????????????????????????????? ??????? Oracle Database 11g R2(???/????) ???????????????? Oracle 11g R2 ????????? - IT Leaders ??????????11g R2?5???? - ??SE????Oracle??? - Think IT ????????????????????????~Oracle Database 11g Release2 ????????? - oracletech.jp ??????????? Oracle Database 11g Release 2(11gR2)|??????????? ???????|???????????

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• Oracle 11gR2:????(RAC/Exadata), ??, ????

  - by Yusuke.Yamamoto

  Oracle Database 11g ?????????????(RAC/Exadata)????????????? ???? 2010/11/17:????? 2011/01/07:???????:Exadata/?? 2011/01/18:???????:Exadata/????????????? 2011/04/21:???????:???????????? 2011/04/21:???????:Exadata/??????????????????????????????????? 2011/06/27:??????:Oracle Exadata Database Machine ????1,000??? 2011/07/06:???????:Exadata/????(?????????????????) 2011/07/08:??????:SAP?Oracle Exadata Database Machine??? 2011/07/15:???????:Exadata/????NTT????KDDI????????????? 2011/07/19:???????:Exadata/????(?????????????????) 2011/08/29:???????:Exadata/?????????(?????????) 2011/08/29:???????:Exadata/????? 2011/08/29:???????:Exadata/????(??????????????) 2011/10/27:???????:Exadata/??? 2011/11/08:???????:Exadata/NTT??? 2012/02/16:???????:Exadata/??????????????? 2012/03/21:???????:Exadata/?????????????(?????????????????) 2012/03/22:???????:Exadata/????? ?? Oracle Database 11g R2 ??????? Oracle Database 11g ?????????(????) Oracle Database 11g ?????????(????:Exadata?) ??????? Oracle Database 11g R2(???/????) Oracle Database 11g R2 ??????? ?? ??? 2009?11?11? Oracle Exadata Database Machine Version 2 ???? 2009?11?17? Oracle Database 11g R2 ???? 2010?02?01? ?????????????????????????????? 2010?03?31? SAP ? Oracle Database 11g R2 ??????????ISV????????·??????????? 2010?05?18? Windows Server 2008 R2 / Windows 7 ?????????Oracle Database 10g R2 ??? 2010?06?23? Oracle Application Express 4.0 ???? 2010?07?09? ?? Windows RDBMS ?????(2009?)????????? 2010?08?17? TPC-C Benchmark Price/Performance ???????? 2010?09?13? Patch Set 11.2.0.2 for Linux ???? 2010?10?20? Oracle Exadata Database Machine X2 ???? 2010?11?17? Oracle Database 11g R2 ????1?? 2010?11?19? ?? Windows RDBMS ?????(2010????)????????????? 2011?03?29? Oracle SQL Developer 3.0 ???? 2011?06?27? Oracle Exadata Database Machine ????1,000????????????????·?????????????? 2011?07?08? SAP ? Oracle Exadata Database Machine ??? 2011?09?01? Oracle Database Express Edition 11g Release 2 ???? 2011?09?23? Patch Set 11.2.0.3 for Linux ???? 2011?11?14? Oracle Database Appliance ???? Oracle Database 11g ?????????(????) ????????????????????????????????(????)? ?[RAC]:Oracle Real Application Clusters(RAC) ???????? ????(??????????) [RAC] ??????????(???) ????? [RAC] ????(???) ?????·???????·??? [RAC] ????? ????·??????·?? ???? ???????(??????????????) [RAC]|???99.999%???????500???????????? - ITpro ??????????? [RAC] ????(????) [RAC] ???(???) ????????(???) [RAC] ??????(???????????) [RAC] Oracle Database 11g ?????????(????:Exadata?) ????????????????????????????????(????)? ?Exadata ??????Oracle Database 11g / Oracle Real Application Clusters(RAC) ?? ?()??????????????? KDDI(??????????????) NTT??? NTT???(???????????) ??????????????? ??? ????(??????) ????????????? ?????·???????·??? ??(??????????????) ?????(??????????) ?????????(SCSK) ?????(????????????) ??????????(???????????) ????(???????) ??????? ?????? ????/????·???????? ???????????(???????/NTT??????????) ????? ?????????????(????/????????????) ???? ????????????|?????? ????|?????????????2013?2????3??????????? - ITpro ??? ?????? ??? ?????(SCSK)|DWH?????????????? - IT Leaders ????(???????????)|???????????·??????????????????????? - oracledatabase.jp Customer Voice ????:????IT?????24??365????????????????????? ?Oracle9i Database ?????????????????????Oracle Database 11g ???????????????????????? Oracle9i Database ???????????????? Customer Voice ??????:Oracle Database 11g????????????????????? ?Oracle ASM ???????????????????I/O????????????????????????????????????? ??????? Oracle Database 11g R2(???/????) ???????????????? Oracle 11g R2 ????????? - IT Leaders ??????????11g R2?5???? - ??SE????Oracle??? - Think IT ????????????????????????~Oracle Database 11g Release2 ????????? - oracletech.jp ??????????? Oracle Database 11g Release 2(11gR2)|??????????? Oracle Exadata|??????????? ???????|???????????

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• PostgreSQL to Data-Warehouse: Best approach for near-real-time ETL / extraction of data

  - by belvoir

  Background: I have a PostgreSQL (v8.3) database that is heavily optimized for OLTP. I need to extract data from it on a semi real-time basis (some-one is bound to ask what semi real-time means and the answer is as frequently as I reasonably can but I will be pragmatic, as a benchmark lets say we are hoping for every 15min) and feed it into a data-warehouse. How much data? At peak times we are talking approx 80-100k rows per min hitting the OLTP side, off-peak this will drop significantly to 15-20k. The most frequently updated rows are ~64 bytes each but there are various tables etc so the data is quite diverse and can range up to 4000 bytes per row. The OLTP is active 24x5.5. Best Solution? From what I can piece together the most practical solution is as follows: Create a TRIGGER to write all DML activity to a rotating CSV log file Perform whatever transformations are required Use the native DW data pump tool to efficiently pump the transformed CSV into the DW Why this approach? TRIGGERS allow selective tables to be targeted rather than being system wide + output is configurable (i.e. into a CSV) and are relatively easy to write and deploy. SLONY uses similar approach and overhead is acceptable CSV easy and fast to transform Easy to pump CSV into the DW Alternatives considered .... Using native logging (http://www.postgresql.org/docs/8.3/static/runtime-config-logging.html). Problem with this is it looked very verbose relative to what I needed and was a little trickier to parse and transform. However it could be faster as I presume there is less overhead compared to a TRIGGER. Certainly it would make the admin easier as it is system wide but again, I don't need some of the tables (some are used for persistent storage of JMS messages which I do not want to log) Querying the data directly via an ETL tool such as Talend and pumping it into the DW ... problem is the OLTP schema would need tweaked to support this and that has many negative side-effects Using a tweaked/hacked SLONY - SLONY does a good job of logging and migrating changes to a slave so the conceptual framework is there but the proposed solution just seems easier and cleaner Using the WAL Has anyone done this before? Want to share your thoughts?

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• int, short, byte performance in back-to-back for-loops

  - by runrunraygun

  (background: http://stackoverflow.com/questions/1097467/why-should-i-use-int-instead-of-a-byte-or-short-in-c) To satisfy my own curiosity about the pros and cons of using the "appropriate size" integer vs the "optimized" integer i wrote the following code which reinforced what I previously held true about int performance in .Net (and which is explained in the link above) which is that it is optimized for int performance rather than short or byte. DateTime t; long a, b, c; t = DateTime.Now; for (int index = 0; index < 127; index++) { Console.WriteLine(index.ToString()); } a = DateTime.Now.Ticks - t.Ticks; t = DateTime.Now; for (short index = 0; index < 127; index++) { Console.WriteLine(index.ToString()); } b=DateTime.Now.Ticks - t.Ticks; t = DateTime.Now; for (byte index = 0; index < 127; index++) { Console.WriteLine(index.ToString()); } c=DateTime.Now.Ticks - t.Ticks; Console.WriteLine(a.ToString()); Console.WriteLine(b.ToString()); Console.WriteLine(c.ToString()); This gives roughly consistent results in the area of... ~950000 ~2000000 ~1700000 which is in line with what i would expect to see. However when I try repeating the loops for each data type like this... t = DateTime.Now; for (int index = 0; index < 127; index++) { Console.WriteLine(index.ToString()); } for (int index = 0; index < 127; index++) { Console.WriteLine(index.ToString()); } for (int index = 0; index < 127; index++) { Console.WriteLine(index.ToString()); } a = DateTime.Now.Ticks - t.Ticks; the numbers are more like... ~4500000 ~3100000 ~300000 Which I find puzzling. Can anyone offer an explanation? NOTE: In the interest of compairing like for like i've limited the loops to 127 because of the range of the byte value type. Also this is an act of curiosity not production code micro-optimization.

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