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  • Server Administration

    - by Kassem
    Hi everyone, My client asked me for a job description of a system administration because I might be assigned this position along with the other guy I'm working with. To be honest, I do not know much about a System Administrator's job but I'm willing to learn. Questions: What are the security requirements of a server? * What are the key responsibilities in a system admin's job description? What are some of the day to day tasks of a system admin? What is the average monthly salary of a system admin? Note: I will be working inside a Windows environment. But your replies do not necessarily need to be constricted to a Windows environment. (*) Other software I know will be required are: Windows Server 2008 IIS 7.0 MS SQL Server .NET 4.0 Runtime Let me know if there are other things I should be aware of as well. Thanks!

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  • Opening the Internet Settings Dialog and using Windows Default Network Settings via Code

    - by Rick Strahl
    Ran into a question from a client the other day that asked how to deal with Internet Connection settings for running  HTTP requests. In this case this is an old FoxPro app and it's using WinInet to handle the actual HTTP connection. Another client asked a similar question about using the IE Web Browser control and configuring connection properties. Regardless of platform or tools used to do HTTP connections, you can probably configure custom connection and proxy settings in your application to configure http connection settings manually. However, this is a repetitive process for each application requires you to track system information in your application which is undesirable. Often it's much easier to rely on the system wide proxy settings that Windows provides via the Internet Settings dialog. The dialog is a Control Panel applet (inetcpl.cpl) and is the same dialog that you see when you pop up Internet Explorer's Options dialog: This dialog controls the Windows connection properties that determine how the Windows HTTP stack connects to the Internet and how Proxy's are used if configured. Depending on how the HTTP client is configured - it can typically inherit and use these global settings. Loading the Settings Dialog Programmatically The settings dialog is a Control Panel applet with the name of: inetcpl.cpl and you can use any Shell execution mechanism (Run dialog, ShellExecute API, Process.Start() in .NET etc.) to invoke the dialog. Changes made there are immediately reflected in any applications that use the default connection settings. In .NET you can simply do this to bring up the Internet Settings dialog with the Connection tab enabled: Process.Start("inetcpl.cpl",",4"); In FoxPro you can simply use the RUN command to execute inetcpl.cpl: lcCmd = "inetcpl.cpl ,4" RUN &lcCmd Using the Default Connection/Proxy Settings When using WinInet you specify the Http connect type in the call to InternetOpen() like this (FoxPro code here): hInetConnection=; InternetOpen(THIS.cUserAgent,0,; THIS.chttpproxyname,THIS.chttpproxybypass,0) The second parameter of 0 specifies that the default system proxy settings should be used and it uses the settings from the Internet Settings Connections tab. Other connection options for HTTP connections include 1 - direct (no proxies and ignore system settings), 3 - explicit Proxy specification. In most situations a connection mode setting of 0 should work. In .NET HTTP connections by default are direct connections and so you need to explicitly specify a default proxy or proxy configuration to use. The easiest way to do this is on the application level in the config file: <configuration> <system.net> <defaultProxy> <proxy bypassonlocal="False" autoDetect="True" usesystemdefault="True" /> </defaultProxy> </system.net> </configuration> You can do the same sort of thing in code specifying the proxy explicitly and using System.Net.WebProxy.GetDefaultProxy(). So when making HTTP calls to Web Services or using the HttpWebRequest class you can set the proxy with: StoreService.Proxy = WebProxy.GetDefaultProxy(); All of this is pretty easy to deal with and in my opinion is a way better choice to managing connection settings than having to track this stuff in your own application. Plus if you use default settings, most of the time it's highly likely that the connection settings are already properly configured making further configuration rare.© Rick Strahl, West Wind Technologies, 2005-2011Posted in Windows  HTTP  .NET  FoxPro   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Beginner Geek: How To Change the Boot Order in Your Computer’s BIOS

    - by Chris Hoffman
    The boot order in your computer’s BIOS controls which device it loads the operating system from. Modify your boot order to force your computer to boot from a USB drive, CD or DVD drive, or another hard drive. You may need to change this setting when booting from another device, whether you’re running an operating system from a live USB drive or installing a new operating system from a disc. Note: This process will look different on each computer. The instructions here will guide you through the process, but the screenshots won’t look exactly the same. How To Use USB Drives With the Nexus 7 and Other Android Devices Why Does 64-Bit Windows Need a Separate “Program Files (x86)” Folder? Why Your Android Phone Isn’t Getting Operating System Updates and What You Can Do About It

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  • Extension Methods in Dot Net 2.0

    - by Tom Hines
    Not that anyone would still need this, but in case you have a situation where the code MUST be .NET 2.0 compliant and you want to use a cool feature like Extension methods, there is a way.  I saw this article when looking for ways to create extension methods in C++, C# and VB:  http://msdn.microsoft.com/en-us/magazine/cc163317.aspx The author shows a simple  way to declare/define the ExtensionAttribute so it's available to 2.0 .NET code. Please read the article to learn about the when and why and use the content below to learn HOW. In the next post, I'll demonstrate cross-language calling of extension methods. Here is a version of it in C# First, here's the project showing there's no VOODOO included: using System; namespace System.Runtime.CompilerServices {    [       AttributeUsage(          AttributeTargets.Assembly          | AttributeTargets.Class          | AttributeTargets.Method,       AllowMultiple = false, Inherited = false)    ]    class ExtensionAttribute : Attribute{} } namespace TestTwoDotExtensions {    public static class Program    {       public static void DoThingCS(this string str)       {          Console.WriteLine("2.0\t{0:G}\t2.0", str);       }       static void Main(string[] args)       {          "asdf".DoThingCS();       }    } }   Here is the C++ version: // TestTwoDotExtensions_CPP.h #pragma once using namespace System; namespace System {        namespace Runtime {               namespace CompilerServices {               [                      AttributeUsage(                            AttributeTargets::Assembly                             | AttributeTargets::Class                            | AttributeTargets::Method,                      AllowMultiple = false, Inherited = false)               ]               public ref class ExtensionAttribute : Attribute{};               }        } } using namespace System::Runtime::CompilerServices; namespace TestTwoDotExtensions_CPP { public ref class CTestTwoDotExtensions_CPP {    public:            [ExtensionAttribute] // or [Extension]            static void DoThingCPP(String^ str)    {       Console::WriteLine("2.0\t{0:G}\t2.0", str);    } }; }

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  • Web application / Domain model integration using JSON capable DTOs [on hold]

    - by g-makulik
    I'm a bit confused about architectural choices for the web-applications/java/python world. For c/c++ world the available (open source) choices to implement web applications is pretty limited to zero, involving java or python the choices explode to a,- hard to sort out -, mess of available 'frameworks' and application approaches. I want to sort out a clean MVC model, where the M stands for a fully blown (POCO, POJO driven) domain model (according M.Fowler's EAA pattern) using a mature OO language (Java,C++) for implementation. The background is: I have a system with certain hardware components (that introduce system immanent active behavior) and a configuration database for system meta and HW-components configuration data (these are even usually self contained, since the HW-components are capable to persist their configuration data anyway). For realization of the configuration/status data exchange protocol with the HW-components we have chosen the Google Protobuf format, which works well for the directly wired communication with these components. This protocol is already used successfully with a Java based GUI application via TCP/IP connection to the main system controlling HW-component. This application has some drawbacks and design flaws for historical reasons. Now we want to develop an abstract model (domain model) for configuration and monitoring those HW-components, that represents a more use case oriented view to the overall system behavior. I have the feeling that a plain Java class model would fit best for this (c++ implementation seems to have too much implementation/integration overhead with viable language-bridge interfaces). Google Protobuf message definitions could still serve well to describe DTO objects used to interact with a domain model API. But integrating Google Protobuf messages client side for e.g. data binding in the current view doesn't seem to be a good choice. I'm thinking about some extra serialization features, e.g. for JSON based data exchange with the views/controllers. Most lightweight solutions seem to involve a python based presentation layer using JSON based data transfer (I'm at least not sure to be fully informed about this). Is there some lightweight (applicable for a limited ARM Linux platform) framework available, supporting such architecture to realize a web-application? UPDATE: According to my recent research and comments of colleagues I've noticed that using Java (and some JVM) might not be the preferable choice for integration with python on a limited linux system as we have (running on ARM9 with hard to discuss memory and MCU costs), but C/C++ modules would do well for this (since this forms the native interface to python extensions, doesn't it?). I can imagine to provide a domain model from an appropriate C/C++ API (though I still think it's more efforts and higher skill requirements for the involved developers to do with these languages). Still I'm searching for a good approach that supports such architecture. I'll appreciate any pointers!

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  • Device cannot be added on software-raid-1 array on Ubuntu 12.04

    - by George Pligor
    Unfortunately all tutorials I have found online until now on how to setup software-raid-1 are outdated on ubuntu 12.40 My target is to setup it on a system with a secondary disk drive that is already running. Format is not an option! I am trying to follow and adapt from 11.10 to 12.04 the following tutorial: http://www.howtoforge.com/how-to-set-up-software-raid1-on-a-running-lvm-system-incl-grub2-configuration-ubuntu-11.10-p2 On the above tutorial there is a successful command which creates a raid-1 array by setting the first disk drive with the installed system as missing: mdadm --create /dev/md0 --level=1 --raid-disks=2 missing /dev/sdb1 But when the time comes to add the first main drive with the installed system on the raid-array with this command: mdadm --add /dev/md0 /dev/sda1 I receive an error message. The error message says that the device /dev/sda is (which makes sense) busy! Note: hardware raid solution is not available since the system is a laptop with two disk drives! Thank you

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  • Changing the default installation path to a newly installed hard disk

    - by mgj
    Hi, I am currently working on a dual-booted PC. I am using Windows XP and Ubuntu 10.04 Lucid Lynx released in April 2010. The allocated partition to Ubuntu that I am making use of has almost exhausted. Current memory allocations on the PC wrt Ubuntu OS looks like this: bodhgaya@pc146724-desktop:~$ df -h Filesystem Size Used Avail Use% Mounted on /dev/sda2 8.6G 8.0G 113M 99% / none 998M 268K 998M 1% /dev none 1002M 580K 1002M 1% /dev/shm none 1002M 100K 1002M 1% /var/run none 1002M 0 1002M 0% /var/lock none 1002M 0 1002M 0% /lib/init/rw /dev/sda1 25G 16G 9.8G 62% /media/C /dev/sdb1 37G 214M 35G 1% /media/ubuntulinuxstore bodhgaya@pc146724-desktop:~$ cd /tmp I am trying to mount a 40GB(/dev/sdb1 - given below) new hard disk along with my existing Ubuntu system to overcome with hard disk space related issues. I referred to the following tutorial to mount a new hard disk onto the system:- http://www.smorgasbord.net/how-to-in...untu-linux%20/ I was able to successfully mount this hard disk for Ubuntu 0S. I have this new hard disk setup in /media/ubuntulinuxstore directory. The current partition in my system looks like this: bodhgaya@pc146724-desktop:/media/ubuntulinuxstore$ sudo fdisk -l [sudo] password for bodhgaya: Disk /dev/sda: 40.0 GB, 40000000000 bytes 255 heads, 63 sectors/track, 4863 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x446eceb5 Device Boot Start End Blocks Id System /dev/sda1 * 2 3264 26210047+ 7 HPFS/NTFS /dev/sda2 3265 4385 9004432+ 83 Linux /dev/sda3 4386 4863 3839535 82 Linux swap / Solaris Disk /dev/sdb: 40.0 GB, 40000000000 bytes 255 heads, 63 sectors/track, 4863 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xfa8afa8a Device Boot Start End Blocks Id System /dev/sdb1 1 4862 39053983+ 7 HPFS/NTFS bodhgaya@pc146724-desktop:/media/ubuntulinuxstore$ Now, I have a concern wrt the "location" where the new softwares will be installed. Generally softwares are installed via the terminal and by default a fixed path is used to where the post installation set up files can be found (I am talking in context of the drive). This is like the typical case of Windows, where softwares by default are installed in the C: drive. These days people customize their installations to a drive which they find apt to serve their purpose (generally based on availability of hard disk space). I am trying to figure out how to customize the same for Ubuntu. As we all know the most softwares are installed via commands given from the Terminal. My road block is how do I redirect the default path set on the terminal where files get installed to this new hard disk. This if done will help me overcome space constraints I am currently facing wrt the partition on which my Ubuntu is initially installed. I would also by this, save time on not formatting my system and reinstalling Ubuntu and other softwares all over again. Please help me with this, your suggestions are much appreciated.

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  • Virtualization in Solaris 11 Express

    - by lynn.rohrer(at)oracle.com
    In Oracle Solaris 10 we introduced Oracle Solaris Containers -- lightweight virtual application environments that allow you to consolidate your Oracle Solaris applications onto a single Oracle Solaris server and make the most of your system resources.The majority of our customers are now using Oracle Solaris Containers on their enterprise systems for applications ranging from web servers to Oracle Database installations. We can also make these Containers highly available with Oracle Solaris Cluster, the industry's first virtualization-aware enterprise cluster product. Using Oracle Solaris Cluster you can failover applications in a Container to another Container on a single system or across systems for additional availability.We've added significant features in Oracle Solaris 11 Express to improve and extend the Oracle Solaris Zone model:Integration of Zones with our new Solaris 11 packaging system (aka Image Packaging System) to provide easy software updates within a zoneSupport for Oracle Solaris 10 Zones to run your Solaris 10 applications unaltered on an Oracle Solaris 11 Express systemIntegration with the new Oracle Solaris 11 network stack architecture (more on this in a future blog post)Improved observability with the zonestat management interface and commandsDelegated administration rights for owners of individual non-global zonesTight integration with Oracle Solaris ZFS to allow dedicated datasets per zoneWith ZFS as the default file system we can now provide easy to manage Boot Environments for zonesThis quick summary is just to whet your appetite to learn more about Oracle Solaris 11 Express Zones enhancements. Fortunately we can serve a full meal at the Oracle Solaris 11 Express Technology Spotlight on Virtualization page on the Oracle Technical Network.

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  • Auto DOP and Concurrency

    - by jean-pierre.dijcks
    After spending some time in the cloud, I figured it is time to come down to earth and start discussing some of the new Auto DOP features some more. As Database Machines (the v2 machine runs Oracle Database 11.2) are effectively selling like hotcakes, it makes some sense to talk about the new parallel features in more detail. For basic understanding make sure you have read the initial post. The focus there is on Auto DOP and queuing, which is to some extend the focus here. But now I want to discuss the concurrency a little and explain some of the relevant parameters and their impact, specifically in a situation with concurrency on the system. The goal of Auto DOP The idea behind calculating the Automatic Degree of Parallelism is to find the highest possible DOP (ideal DOP) that still scales. In other words, if we were to increase the DOP even more  above a certain DOP we would see a tailing off of the performance curve and the resource cost / performance would become less optimal. Therefore the ideal DOP is the best resource/performance point for that statement. The goal of Queuing On a normal production system we should see statements running concurrently. On a Database Machine we typically see high concurrency rates, so we need to find a way to deal with both high DOP’s and high concurrency. Queuing is intended to make sure we Don’t throttle down a DOP because other statements are running on the system Stay within the physical limits of a system’s processing power Instead of making statements go at a lower DOP we queue them to make sure they will get all the resources they want to run efficiently without trashing the system. The theory – and hopefully – practice is that by giving a statement the optimal DOP the sum of all statements runs faster with queuing than without queuing. Increasing the Number of Potential Parallel Statements To determine how many statements we will consider running in parallel a single parameter should be looked at. That parameter is called PARALLEL_MIN_TIME_THRESHOLD. The default value is set to 10 seconds. So far there is nothing new here…, but do realize that anything serial (e.g. that stays under the threshold) goes straight into processing as is not considered in the rest of this post. Now, if you have a system where you have two groups of queries, serial short running and potentially parallel long running ones, you may want to worry only about the long running ones with this parallel statement threshold. As an example, lets assume the short running stuff runs on average between 1 and 15 seconds in serial (and the business is quite happy with that). The long running stuff is in the realm of 1 – 5 minutes. It might be a good choice to set the threshold to somewhere north of 30 seconds. That way the short running queries all run serial as they do today (if it ain’t broken, don’t fix it) and allows the long running ones to be evaluated for (higher degrees of) parallelism. This makes sense because the longer running ones are (at least in theory) more interesting to unleash a parallel processing model on and the benefits of running these in parallel are much more significant (again, that is mostly the case). Setting a Maximum DOP for a Statement Now that you know how to control how many of your statements are considered to run in parallel, lets talk about the specific degree of any given statement that will be evaluated. As the initial post describes this is controlled by PARALLEL_DEGREE_LIMIT. This parameter controls the degree on the entire cluster and by default it is CPU (meaning it equals Default DOP). For the sake of an example, let’s say our Default DOP is 32. Looking at our 5 minute queries from the previous paragraph, the limit to 32 means that none of the statements that are evaluated for Auto DOP ever runs at more than DOP of 32. Concurrently Running a High DOP A basic assumption about running high DOP statements at high concurrency is that you at some point in time (and this is true on any parallel processing platform!) will run into a resource limitation. And yes, you can then buy more hardware (e.g. expand the Database Machine in Oracle’s case), but that is not the point of this post… The goal is to find a balance between the highest possible DOP for each statement and the number of statements running concurrently, but with an emphasis on running each statement at that highest efficiency DOP. The PARALLEL_SERVER_TARGET parameter is the all important concurrency slider here. Setting this parameter to a higher number means more statements get to run at their maximum parallel degree before queuing kicks in.  PARALLEL_SERVER_TARGET is set per instance (so needs to be set to the same value on all 8 nodes in a full rack Database Machine). Just as a side note, this parameter is set in processes, not in DOP, which equates to 4* Default DOP (2 processes for a DOP, default value is 2 * Default DOP, hence a default of 4 * Default DOP). Let’s say we have PARALLEL_SERVER_TARGET set to 128. With our limit set to 32 (the default) we are able to run 4 statements concurrently at the highest DOP possible on this system before we start queuing. If these 4 statements are running, any next statement will be queued. To run a system at high concurrency the PARALLEL_SERVER_TARGET should be raised from its default to be much closer (start with 60% or so) to PARALLEL_MAX_SERVERS. By using both PARALLEL_SERVER_TARGET and PARALLEL_DEGREE_LIMIT you can control easily how many statements run concurrently at good DOPs without excessive queuing. Because each workload is a little different, it makes sense to plan ahead and look at these parameters and set these based on your requirements.

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  • Gnome keyring doesn't unlock after loging in using Pam-face-authentication.

    - by Gaurav Butola
    I am using http://pam-face-authentication.org/ to log into my system using face detection and it is working just great except for one thing,The authentication runs out of the box, but it doesn't unlock my keyring. So after loging into my system, I see my desktop and everything normally but then a password prompt pops-up asking for Gnome-keyring, I think if it can log me into the system just fine then it should also be able to unlock the gnome-kerying. This guy also have the same issue -- https://bugs.launchpad.net/gdm/+bug/479881/comments/4

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  • Linux - Imaging backup solution?

    - by xperator
    I want to know is there a way to make a snapshot-like backup of a linux system into a single file and restore it in another system ? You know in windows there are programs which makes a copy of a drive (like C:\ ) into a single image file. So you can restore this file later incase you are infected or something happens. Every time I want to migrate my vps into another host, I have to setup the new server from scratch and move the files manually. Can I just make a snapshot backup of the whole system and restore it somewhere else (or on the same server) ? I am not familiar with linux and I have no idea if this is technically possible or not ? Does the paritions, configs, system files,etc... are individual for each system ? I heard about rsync, but that's not what I am looking for.

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  • CCNet TFS Migration - Dealing with left over folders

    - by Michael Stephenson
    Im currently in the process of migrating our many BizTalk projects from MKS source control to TFS.  While we will be using TFS for work item tracking and source control etc we will be continuing to use Cruise Control for continuous integration although im updating this to CCNet 1.5 at the same time. Ill post a few things as much as a reminder to myself about some of the problems we come across. Problem After the first build of our code the next time a build is triggered an error is encountered by the TFS source control block refreshing the source code. System.IO.IOException: The directory is not empty.    at System.IO.Directory.DeleteHelper(String fullPath, String userPath, Boolean recursive)    at System.IO.Directory.Delete(String fullPath, String userPath, Boolean recursive)    at ThoughtWorks.CruiseControl.Core.Sourcecontrol.Vsts.deleteDirectory(String path)    at ThoughtWorks.CruiseControl.Core.Sourcecontrol.Vsts.GetSource(IIntegrationResult result)    at ThoughtWorks.CruiseControl.Core.IntegrationRunner.Build(IIntegrationResult result)    at ThoughtWorks.CruiseControl.Core.IntegrationRunner.Integrate(IntegrationRequest request) System.IO.IOException: The directory is not empty. at System.IO.Directory.DeleteHelper(String fullPath, String userPath, Boolean recursive) at System.IO.Directory.Delete(String fullPath, String userPath, Boolean recursive) at ThoughtWorks.CruiseControl.Core.Sourcecontrol.Vsts.deleteDirectory(String path) at ThoughtWorks.CruiseControl.Core.Sourcecontrol.Vsts.GetSource(IIntegrationResult result) at ThoughtWorks.CruiseControl.Core.IntegrationRunner.Build(IIntegrationResult result) at ThoughtWorks.CruiseControl.Core.IntegrationRunner.Integrate(IntegrationRequest request) Project: Bupa.BPI.Documents Date of build: 2011-01-28 14:54:21 Running time: 00:00:05 Integration Request: Build (ForceBuild) triggered from VMOPBZDEV11 Solution The problem seems to be with a folder called TestLocations which is created by the build process and used along with the file adapter as a way to get messages into BizTalk.  For some reason the source control block when it does a full refresh of the code does not get rid of this folder and then complains thats a problem and fails the build. Interestingly there are other folders created by the build which are deleted fine.  My assumption is that this if something to do with the file adapter polling the directory.  However note that we have not had this problem with other source control blocks in the past. To workaround this I have added a prebuild task to the ccnet.config file to delete this folder before the source control block is executed.  See below for example < prebuild> exec>executable>cmd.exe</executable>buildArgs>/c "if exist "C:\<MyCode>\TestLocations" rd /s /q "C:\<MyCode>\TestLocations""</buildArgs>exec> prebuild> < < < </ </

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  • Securing ASP.Net Pages - Forms Authentication - C# and .Net 4

    - by SAMIR BHOGAYTA
    ASP.Net has a built-in feature named Forms Authentication that allows a developer to easily secure certain areas of a web site. In this post I'm going to build a simple authentication sample using C# and ASP.Net 4.0 (still in beta as of the posting date). Security settings with ASP.Net is configured from within the web.config file. This is a standard ASCII file, with an XML format, that is located in the root of your web application. Here is a sample web.config file: configuration system.web authenticationmode="Forms" formsname="TestAuthCookie"loginUrl="login.aspx"timeout="30" credentialspasswordFormat="Clear" username="user1"password="pass1"/ username="user2"password="pass2"/ authorization denyusers="?"/ compilationtargetFramework="4.0"/ pagescontrolRenderingCompatibilityVersion="3.5"clientIDMode="AutoID"/ Here is the complete source of the sample login.aspx page: div Username: asp:TextBox ID="txtUsername" runat="server":TextBox Password: asp:TextBox ID="txtPassword" runat="server":TextBox asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Login" / asp:Label ID="lblStatus" runat="server" Text="Please login":Label /div And here is the complete source of the login.aspx.cs file: using System; using System.Web.UI.WebControls; using System.Web.Security; public partial class Default3 : System.Web.UI.Page { protected void Button1_Click(object sender, EventArgs e) { if (FormsAuthentication.Authenticate(txtUsername.Text, txtPassword.Text)) { lblStatus.Text = ("Welcome " + txtUsername.Text); FormsAuthentication.RedirectFromLoginPage(txtUsername.Text, true); } else { lblStatus.Text = "Invalid login!"; } } }

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  • SQL SERVER – ASYNC_IO_COMPLETION – Wait Type – Day 11 of 28

    - by pinaldave
    For any good system three things are vital: CPU, Memory and IO (disk). Among these three, IO is the most crucial factor of SQL Server. Looking at real-world cases, I do not see IT people upgrading CPU and Memory frequently. However, the disk is often upgraded for either improving the space, speed or throughput. Today we will look at another IO-related wait type. From Book On-Line: Occurs when a task is waiting for I/Os to finish. ASYNC_IO_COMPLETION Explanation: Any tasks are waiting for I/O to finish. If by any means your application that’s connected to SQL Server is processing the data very slowly, this type of wait can occur. Several long-running database operations like BACKUP, CREATE DATABASE, ALTER DATABASE or other operations can also create this wait type. Reducing ASYNC_IO_COMPLETION wait: When it is an issue related to IO, one should check for the following things associated to IO subsystem: Look at the programming and see if there is any application code which processes the data slowly (like inefficient loop, etc.). Note that it should be re-written to avoid this  wait type. Proper placing of the files is very important. We should check the file system for proper placement of the files – LDF and MDF on separate drive, TempDB on another separate drive, hot spot tables on separate filegroup (and on separate disk), etc. Check the File Statistics and see if there is a higher IO Read and IO Write Stall SQL SERVER – Get File Statistics Using fn_virtualfilestats. Check event log and error log for any errors or warnings related to IO. If you are using SAN (Storage Area Network), check the throughput of the SAN system as well as configuration of the HBA Queue Depth. In one of my recent projects, the SAN was performing really badly and so the SAN administrator did not accept it. After some investigations, he agreed to change the HBA Queue Depth on the development setup (test environment). As soon as we changed the HBA Queue Depth to quite a higher value, there was a sudden big improvement in the performance. It is very likely to happen that there are no proper indexes on the system and yet there are lots of table scans and heap scans. Creating proper index can reduce the IO bandwidth considerably. If SQL Server can use appropriate cover index instead of clustered index, it can effectively reduce lots of CPU, Memory and IO (considering cover index has lesser columns than cluster table and all other; it depends upon the situation). You can refer to the following two articles I wrote that talk about how to optimize indexes: Create Missing Indexes Drop Unused Indexes Checking Memory Related Perfmon Counters SQLServer: Memory Manager\Memory Grants Pending (Consistent higher value than 0-2) SQLServer: Memory Manager\Memory Grants Outstanding (Consistent higher value, Benchmark) SQLServer: Buffer Manager\Buffer Hit Cache Ratio (Higher is better, greater than 90% for usually smooth running system) SQLServer: Buffer Manager\Page Life Expectancy (Consistent lower value than 300 seconds) Memory: Available Mbytes (Information only) Memory: Page Faults/sec (Benchmark only) Memory: Pages/sec (Benchmark only) Checking Disk Related Perfmon Counters Average Disk sec/Read (Consistent higher value than 4-8 millisecond is not good) Average Disk sec/Write (Consistent higher value than 4-8 millisecond is not good) Average Disk Read/Write Queue Length (Consistent higher value than benchmark is not good) Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussions of Wait Stats in this blog are generic and vary from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • XNA 2D Collision with specific tiles

    - by zenzero
    I am new to game programming and to these sites for help. I am making a 2D game but I can't seem to get the collision between my character and certain tiles. I have a map filled with grass tiles and water tiles and I want to keep my character from walking on the water tiles. I have a Tiles class that I use so that the tiles are objects and also has the collision method in it, a TileEngine class used create the map and it also holds a list of Tiles, and the class James which is for my character. I also have a Camera class that centers the camera on my character if that has anything to do with the problem. The character's movement is intended to be restricted to 4 directions(up, down, left, right). As an extra note, the bottom right water tile does have collision, but the collision does not occur for any of the other water tiles. Here is my TileEngine class using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; namespace Test2DGame2 { class TileEngine : Microsoft.Xna.Framework.Game { //makes a list of Tiles objects public List<Tiles> tilesList = new List<Tiles>(); public TileEngine() {} public static int tileWidth = 64; public static int tileHeight = 64; public int[,] map = { {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,}, }; public void drawMap(SpriteBatch spriteBatch) { for (int y = 0; y < map.GetLength(0); y++) { for (int x = 0; x < map.GetLength(1); x++) { //make a Rectangle tilesList[map[y, x]].rectangle = new Rectangle(x * tileWidth, y * tileHeight, tileWidth, tileHeight); //draw the Tiles objects spriteBatch.Draw(tilesList[map[y, x]].texture, tilesList[map[y, x]].rectangle, Color.White); } } } } } Here is my Tiles class using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; namespace Test2DGame2 { class Tiles { public Texture2D texture; public Rectangle rectangle; public Tiles(Texture2D texture) { this.texture = texture; } //check to see if james collides with the tile from the right side public void rightCollision(James james) { if (james.GetBounds().Intersects(rectangle)) { james.position.X = rectangle.Left - james.front.Width; } } } } I have a method for rightCollision because I could only figure out how to get the collisions from specifying directions. and here is the James class for my character using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; namespace Test2DGame2 { class James { public Texture2D front; public Texture2D back; public Texture2D left; public Texture2D right; public Vector2 center; public Vector2 position; public James(Texture2D front) { position = new Vector2(0, 0); this.front = front; center = new Vector2(front.Width / 2, front.Height / 2); } public James(Texture2D front, Vector2 newPosition) { this.front = front; position = newPosition; center = new Vector2(front.Width / 2, front.Height / 2); } public void move(GameTime gameTime) { KeyboardState keyboard = Keyboard.GetState(); float SCALE = 20.0f; float speed = gameTime.ElapsedGameTime.Milliseconds / 100.0f; if (keyboard.IsKeyDown(Keys.Up)) { position.Y -=speed * SCALE; } else if (keyboard.IsKeyDown(Keys.Down)) { position.Y += speed * SCALE; } else if (keyboard.IsKeyDown(Keys.Left)) { position.X -= speed * SCALE; } else if (keyboard.IsKeyDown(Keys.Right)) { position.X += speed * SCALE; } } public void draw(SpriteBatch spriteBatch) { spriteBatch.Draw(front, position, null, Color.White, 0, center, 1.0f, SpriteEffects.None, 0.0f); } //get the boundingbox for James public Rectangle GetBounds() { return new Rectangle( (int)position.X, (int)position.Y, front.Width, front.Height); } } }

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  • Should classes from the same namespace be kept in the same assembly?

    - by Dan Rasmussen
    For example, ISerializable and the Serializable Attribute are both in the System.Runtime.Serialization namespace, but not the assembly of the same name. On the other hand, DataContract attributes are in the namespace/assembly System.Runtime.Serialization. This causes confusion when a class can have using System.Runtime.Serialization but still not have reference to the System.Runtime.Serialization assembly, meaning DataContract cannot be found. Should this be avoided in practice, or is it common for namespaces to be split over multiple assemblies? What other issues should one be careful of when doing this?

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  • SQL SERVER – IO_COMPLETION – Wait Type – Day 10 of 28

    - by pinaldave
    For any good system three things are vital: CPU, Memory and IO (disk). Among these three, IO is the most crucial factor of SQL Server. Looking at real-world cases, I do not see IT people upgrading CPU and Memory frequently. However, the disk is often upgraded for either improving the space, speed or throughput. Today we will look at an IO-related wait types. From Book On-Line: Occurs while waiting for I/O operations to complete. This wait type generally represents non-data page I/Os. Data page I/O completion waits appear as PAGEIOLATCH_* waits. IO_COMPLETION Explanation: Any tasks are waiting for I/O to finish. This is a good indication that IO needs to be looked over here. Reducing IO_COMPLETION wait: When it is an issue concerning the IO, one should look at the following things related to IO subsystem: Proper placing of the files is very important. We should check the file system for proper placement of files – LDF and MDF on a separate drive, TempDB on another separate drive, hot spot tables on separate filegroup (and on separate disk),etc. Check the File Statistics and see if there is higher IO Read and IO Write Stall SQL SERVER – Get File Statistics Using fn_virtualfilestats. Check event log and error log for any errors or warnings related to IO. If you are using SAN (Storage Area Network), check the throughput of the SAN system as well as the configuration of the HBA Queue Depth. In one of my recent projects, the SAN was performing really badly so the SAN administrator did not accept it. After some investigations, he agreed to change the HBA Queue Depth on development (test environment) set up and as soon as we changed the HBA Queue Depth to quite a higher value, there was a sudden big improvement in the performance. It is very possible that there are no proper indexes in the system and there are lots of table scans and heap scans. Creating proper index can reduce the IO bandwidth considerably. If SQL Server can use appropriate cover index instead of clustered index, it can effectively reduce lots of CPU, Memory and IO (considering cover index has lesser columns than cluster table and all other; it depends upon the situation). You can refer to the two articles that I wrote; they are about how to optimize indexes: Create Missing Indexes Drop Unused Indexes Checking Memory Related Perfmon Counters SQLServer: Memory Manager\Memory Grants Pending (Consistent higher value than 0-2) SQLServer: Memory Manager\Memory Grants Outstanding (Consistent higher value, Benchmark) SQLServer: Buffer Manager\Buffer Hit Cache Ratio (Higher is better, greater than 90% for usually smooth running system) SQLServer: Buffer Manager\Page Life Expectancy (Consistent lower value than 300 seconds) Memory: Available Mbytes (Information only) Memory: Page Faults/sec (Benchmark only) Memory: Pages/sec (Benchmark only) Checking Disk Related Perfmon Counters Average Disk sec/Read (Consistent higher value than 4-8 millisecond is not good) Average Disk sec/Write (Consistent higher value than 4-8 millisecond is not good) Average Disk Read/Write Queue Length (Consistent higher value than benchmark is not good) Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussions of Wait Stats in this blog are generic and vary from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Types, SQL White Papers, T SQL, Technology

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  • Windows 7 - Ubuntu 10.10 Dual Boot Partitioning Recommendation for HP Laptop OEM

    - by Denja
    Hi Linux Community, After been temporary impressed with the newb Windows 7 and after intensly using it I find my self struggling with the ever slow and buggy windows OS once again. It's Time to go with the Ubuntu/Linux way for a better and faster tomorrow. Unfortunately in my country most Users/Business use Windows based Systems. As a Computer technician i want to learn and use both Systems and possibly introduce New users to more affordable Linux Based Systems. For now I want to create dual-boot or even triple boot layouts on my laptop machine Here's the layout in use now: * (C:) Windows 7 system partition NTFS - 284,89GB (Primary,Boot,Pagefile,Dump) * HP_TOOLS system partition FAT32 - 99MB (Primary) * (D:) RECOVERY partition NTFS - 12,90GB (Primary) * SYSTEM partition NTFS 199MB (Primary) Here's the layout I want to make. * (C:) Windows 7 system partition NTFS - 60GB (Primary) (sda1) * (D:) Windows data partition (user files) NTFS - 60GB(Extended or Primary)(sda2);wanna share with Linux * Linux root Ext4 - 10GB (Primary)(sda3) * Linux swap swap- RAM size, 3GB (sda4) * Linux home Ext4- 164,9GB (Extended)(sda5) Question 1: Is the layout that i want to make correct as the Primary and Extended Partition concerns ? Question 2: Can I definitely get rid of SYSTEM Boot loader of windows? Question 3: If I get rid of HP_TOOLS and RECOVERY partition will it be a problem? Question 4: Based on my layout what is your suggestion for a Triple Boot layout for OSX or Puppy Linux? Thank you in advance for your advises and suggestions.

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  • HDD vanished after wakeup from standby

    - by Sam
    In my computer I got two hard drives: One 80GB Intel X25 Postville SSD for the system and a 1,5TB Sata HDD for data. When I put the system into standby, and wake it up again, roundabout 50% of the time the 1,5TB HDD is not found. It just vanished from the system (wreaking havok to all programs running which had open files on it). Even going into the system management and refreshing the drives does not find the lost HDD. There are no messages about this in the event log. After a warm reboot the hdd is found again, just like it should. The system is a Shuttle SP35P2 Pro with 8GB Ram and DualCore CPU, OS is Windows 7 Ultimate. I even set up the OS anew, didn't help. Any ideas what might cause this? How to debug, or maybe even fix it?

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  • The type 'XXX' is defined in an assembly that is not referenced exception after upgrade to ASP.NET 4

    - by imran_ku07
       Introduction :          I found two posts in ASP.NET MVC forums complaining that they are getting exception, The type XXX is defined in an assembly that is not referenced, after upgrading thier application into Visual Studio 2010 and .NET Framework 4.0 at here and here .   Description :           The reason why they are getting the above exception is the use of new clean web.config without referencing the assemblies which were presents in ASP.NET 3.5 web.config. The quick solution for this problem is to add the old assemblies in new web.config.          <assemblies>             <add assembly="System.Web.Abstractions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>             <add assembly="System.Web.Routing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>             <add assembly="System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>              <add assembly="System.Data.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />              <add assembly="System.Data.Linq, Version=4.0.0.0, Culture=neutral, publicKeyToken=b77a5c561934e089" />          </assemblies>    How It works :            Currently i have not tested the above scenario in ASP.NET 4.0 because i have not yet get it. But the above scenario can easily be tested and verified in VS 2008. Just Open the root web.config and remove           <add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>             Even you add the reference of System.Core in your project, you will still get the above exception because aspx pages are compiled in separate assembly. You can check this yourself by checking Show Detailed Compiler Output: below in the yellow screen of death, you will find something,/out:"C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\e907aee4\5fa0acc8\App_Web_y5rd6bdg.dll"             This shows that aspx pages are compiled in separate assembly in Temporary ASP.NET Files.Summary :             After getting the above exception make sure to add the assemblies in web.config or add the Assembly directive at Page level. Hopefully this will helps to solve your problem.       

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  • Screwed Up Again, Did Ya?

    - by rickramsey
    Your turn to wear the Cantaloupe Cap of Shame? Here's how to keep it from happening again: Figure out what data you need to archive Create a solid archive someplace safer than your iphone Get wicked fast at recovering your system. Jesse Butler explains how to do all three for a system running Oracle Solaris 11: How to Recover an Oracle Solaris 11 System Website Newsletter Facebook Twitter

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  • Thread placement policies on NUMA systems - update

    - by Dave
    In a prior blog entry I noted that Solaris used a "maximum dispersal" placement policy to assign nascent threads to their initial processors. The general idea is that threads should be placed as far away from each other as possible in the resource topology in order to reduce resource contention between concurrently running threads. This policy assumes that resource contention -- pipelines, memory channel contention, destructive interference in the shared caches, etc -- will likely outweigh (a) any potential communication benefits we might achieve by packing our threads more densely onto a subset of the NUMA nodes, and (b) benefits of NUMA affinity between memory allocated by one thread and accessed by other threads. We want our threads spread widely over the system and not packed together. Conceptually, when placing a new thread, the kernel picks the least loaded node NUMA node (the node with lowest aggregate load average), and then the least loaded core on that node, etc. Furthermore, the kernel places threads onto resources -- sockets, cores, pipelines, etc -- without regard to the thread's process membership. That is, initial placement is process-agnostic. Keep reading, though. This description is incorrect. On Solaris 10 on a SPARC T5440 with 4 x T2+ NUMA nodes, if the system is otherwise unloaded and we launch a process that creates 20 compute-bound concurrent threads, then typically we'll see a perfect balance with 5 threads on each node. We see similar behavior on an 8-node x86 x4800 system, where each node has 8 cores and each core is 2-way hyperthreaded. So far so good; this behavior seems in agreement with the policy I described in the 1st paragraph. I recently tried the same experiment on a 4-node T4-4 running Solaris 11. Both the T5440 and T4-4 are 4-node systems that expose 256 logical thread contexts. To my surprise, all 20 threads were placed onto just one NUMA node while the other 3 nodes remained completely idle. I checked the usual suspects such as processor sets inadvertently left around by colleagues, processors left offline, and power management policies, but the system was configured normally. I then launched multiple concurrent instances of the process, and, interestingly, all the threads from the 1st process landed on one node, all the threads from the 2nd process landed on another node, and so on. This happened even if I interleaved thread creating between the processes, so I was relatively sure the effect didn't related to thread creation time, but rather that placement was a function of process membership. I this point I consulted the Solaris sources and talked with folks in the Solaris group. The new Solaris 11 behavior is intentional. The kernel is no longer using a simple maximum dispersal policy, and thread placement is process membership-aware. Now, even if other nodes are completely unloaded, the kernel will still try to pack new threads onto the home lgroup (socket) of the primordial thread until the load average of that node reaches 50%, after which it will pick the next least loaded node as the process's new favorite node for placement. On the T4-4 we have 64 logical thread contexts (strands) per socket (lgroup), so if we launch 48 concurrent threads we will find 32 placed on one node and 16 on some other node. If we launch 64 threads we'll find 32 and 32. That means we can end up with our threads clustered on a small subset of the nodes in a way that's quite different that what we've seen on Solaris 10. So we have a policy that allows process-aware packing but reverts to spreading threads onto other nodes if a node becomes too saturated. It turns out this policy was enabled in Solaris 10, but certain bugs suppressed the mixed packing/spreading behavior. There are configuration variables in /etc/system that allow us to dial the affinity between nascent threads and their primordial thread up and down: see lgrp_expand_proc_thresh, specifically. In the OpenSolaris source code the key routine is mpo_update_tunables(). This method reads the /etc/system variables and sets up some global variables that will subsequently be used by the dispatcher, which calls lgrp_choose() in lgrp.c to place nascent threads. Lgrp_expand_proc_thresh controls how loaded an lgroup must be before we'll consider homing a process's threads to another lgroup. Tune this value lower to have it spread your process's threads out more. To recap, the 'new' policy is as follows. Threads from the same process are packed onto a subset of the strands of a socket (50% for T-series). Once that socket reaches the 50% threshold the kernel then picks another preferred socket for that process. Threads from unrelated processes are spread across sockets. More precisely, different processes may have different preferred sockets (lgroups). Beware that I've simplified and elided details for the purposes of explication. The truth is in the code. Remarks: It's worth noting that initial thread placement is just that. If there's a gross imbalance between the load on different nodes then the kernel will migrate threads to achieve a better and more even distribution over the set of available nodes. Once a thread runs and gains some affinity for a node, however, it becomes "stickier" under the assumption that the thread has residual cache residency on that node, and that memory allocated by that thread resides on that node given the default "first-touch" page-level NUMA allocation policy. Exactly how the various policies interact and which have precedence under what circumstances could the topic of a future blog entry. The scheduler is work-conserving. The x4800 mentioned above is an interesting system. Each of the 8 sockets houses an Intel 7500-series processor. Each processor has 3 coherent QPI links and the system is arranged as a glueless 8-socket twisted ladder "mobius" topology. Nodes are either 1 or 2 hops distant over the QPI links. As an aside the mapping of logical CPUIDs to physical resources is rather interesting on Solaris/x4800. On SPARC/Solaris the CPUID layout is strictly geographic, with the highest order bits identifying the socket, the next lower bits identifying the core within that socket, following by the pipeline (if present) and finally the logical thread context ("strand") on the core. But on Solaris on the x4800 the CPUID layout is as follows. [6:6] identifies the hyperthread on a core; bits [5:3] identify the socket, or package in Intel terminology; bits [2:0] identify the core within a socket. Such low-level details should be of interest only if you're binding threads -- a bad idea, the kernel typically handles placement best -- or if you're writing NUMA-aware code that's aware of the ambient placement and makes decisions accordingly. Solaris introduced the so-called critical-threads mechanism, which is expressed by putting a thread into the FX scheduling class at priority 60. The critical-threads mechanism applies to placement on cores, not on sockets, however. That is, it's an intra-socket policy, not an inter-socket policy. Solaris 11 introduces the Power Aware Dispatcher (PAD) which packs threads instead of spreading them out in an attempt to be able to keep sockets or cores at lower power levels. Maximum dispersal may be good for performance but is anathema to power management. PAD is off by default, but power management polices constitute yet another confounding factor with respect to scheduling and dispatching. If your threads communicate heavily -- one thread reads cache lines last written by some other thread -- then the new dense packing policy may improve performance by reducing traffic on the coherent interconnect. On the other hand if your threads in your process communicate rarely, then it's possible the new packing policy might result on contention on shared computing resources. Unfortunately there's no simple litmus test that says whether packing or spreading is optimal in a given situation. The answer varies by system load, application, number of threads, and platform hardware characteristics. Currently we don't have the necessary tools and sensoria to decide at runtime, so we're reduced to an empirical approach where we run trials and try to decide on a placement policy. The situation is quite frustrating. Relatedly, it's often hard to determine just the right level of concurrency to optimize throughput. (Understanding constructive vs destructive interference in the shared caches would be a good start. We could augment the lines with a small tag field indicating which strand last installed or accessed a line. Given that, we could augment the CPU with performance counters for misses where a thread evicts a line it installed vs misses where a thread displaces a line installed by some other thread.)

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  • Cross-language Extension Method Calling

    - by Tom Hines
    Extension methods are a concise way of binding functions to particular types. In my last post, I showed how Extension methods can be created in the .NET 2.0 environment. In this post, I discuss calling the extensions from other languages. Most of the differences I find between the Dot Net languages are mainly syntax.  The declaration of Extensions is no exception.  There is, however, a distinct difference with the framework accepting excensions made with C++ that differs from C# and VB.  When calling the C++ extension from C#, the compiler will SOMETIMES say there is no definition for DoCPP with the error: 'string' does not contain a definition for 'DoCPP' and no extension method 'DoCPP' accepting a first argument of type 'string' could be found (are you missing a using directive or an assembly reference?) If I recompile, the error goes away. The strangest problem with calling the C++ extension from C# is that I first must make SOME type of reference to the class BEFORE using the extension or it will not be recognized at all.  So, if I first call the DoCPP() as a static method, the extension works fine later.  If I make a dummy instantiation of the class, it works.  If I have no forward reference of the class, I get the same error as before and recompiling does not fix it.  It seems as if this none of this is supposed to work across the languages. I have made a few work-arounds to get the examples to compile and run. Note the following examples: Extension in C# using System; namespace Extension_CS {    public static class CExtension_CS    {  //in C#, the "this" keyword is the key.       public static void DoCS(this string str)       {          Console.WriteLine("CS\t{0:G}\tCS", str);       }    } } Extension in C++ /****************************************************************************\  * Here is the C++ implementation.  It is the least elegant and most quirky,  * but it works. \****************************************************************************/ #pragma once using namespace System; using namespace System::Runtime::CompilerServices;     //<-Essential // Reference: System.Core.dll //<- Essential namespace Extension_CPP {        public ref class CExtension_CPP        {        public:               [Extension] // or [ExtensionAttribute] /* either works */               static void DoCPP(String^ str)               {                      Console::WriteLine("C++\t{0:G}\tC++", str);               }        }; } Extension in VB ' Here is the VB implementation.  This is not as elegant as the C#, but it's ' functional. Imports System.Runtime.CompilerServices ' Public Module modExtension_VB 'Extension methods can be defined only in modules.    <Extension()> _       Public Sub DoVB(ByVal str As String)       Console.WriteLine("VB" & Chr(9) & "{0:G}" & Chr(9) & "VB", str)    End Sub End Module   Calling program in C# /******************************************************************************\  * Main calling program  * Intellisense and VS2008 complain about the CPP implementation, but with a  * little duct-tape, it works just fine. \******************************************************************************/ using System; using Extension_CPP; using Extension_CS; using Extension_VB; // vitual namespace namespace TestExtensions {    public static class CTestExtensions    {       /**********************************************************************\        * For some reason, this needs a direct reference into the C++ version        * even though it does nothing than add a null reference.        * The constructor provides the fake usage to please the compiler.       \**********************************************************************/       private static CExtension_CPP x = null;   // <-DUCT_TAPE!       static CTestExtensions()       {          // Fake usage to stop compiler from complaining          if (null != x) {} // <-DUCT_TAPE       }       static void Main(string[] args)       {          string strData = "from C#";          strData.DoCPP();          strData.DoCS();          strData.DoVB();       }    } }   Calling program in VB  Imports Extension_CPP Imports Extension_CS Imports Extension_VB Imports System.Runtime.CompilerServices Module TestExtensions_VB    <Extension()> _       Public Sub DoCPP(ByVal str As String)       'Framework does not treat this as an extension, so use the static       CExtension_CPP.DoCPP(str)    End Sub    Sub Main()       Dim strData As String = "from VB"       strData.DoCS()       strData.DoVB()       strData.DoCPP() 'fake    End Sub End Module  Calling program in C++ // TestExtensions_CPP.cpp : main project file. #include "stdafx.h" using namespace System; using namespace Extension_CPP; using namespace Extension_CS; using namespace Extension_VB; void main(void) {        /*******************************************************\         * Extension methods are called like static methods         * when called from C++.  There may be a difference in         * syntax when calling the VB extension as VB Extensions         * are embedded in Modules instead of classes        \*******************************************************/     String^ strData = "from C++";     CExtension_CPP::DoCPP(strData);     CExtension_CS::DoCS(strData);     modExtension_VB::DoVB(strData); //since Extensions go in Modules }

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