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• Best SSD tweaks for Windows 7

  - by Nick Berardi

  I have seen many articles about tweaking an SSD, but many of them seem outdated, or too broad (read all Windows XP, Vista, and Windows 7 general tweaks). And I know that Windows 7 has been specifically tweaked for SSD by the Windows team, so I don't want to do something that was written for Windows XP in mind and end up circumventing something the Windows team has specifically designed in to Windows 7. So my question is what are the best SSD tweaks for Windows 7 that you have found to get the performance out of your drive? I hope to make a comprehensive list in the answers below so there won't be so much disinformation in the forums about what to do and what not to do. Here are a few that I see posted up on the forums alot, and some questions to get the discussion started: Disabling Superfetch. Yes or No Disabling Page File or limiting it to a really small size such as 500 MB. Disabling Indexing. Yes or No Disabling Defragmenting. Yes or No What are your thoughts do you have any that have worked for you? When providing an answer please do your best to back it up with a reason and possibly some documentation from MSDN, TechNet, or another credible source.

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• (Win7) Gets stuck with ~1% CPU. Especially with multithreading

  - by meow

  Windows 7 32 bit, up to date, Intel i7 860. (For some reason the company runs 32bit Windows everywhere.) I tried to update all motherboard drivers etc. as far as possible. I have a performance issue with a machine which appears in connection with multithreading (or so I think). As an example (and where I most often see it, but it appears on other programs as well): ProteoWizard is a file conversion tool for mass spectrometry files. I can add a list of files and it will attempt to process up to 8 files in parallel (quadcore x 2 threads/core). If I choose 1 to 6 files, I start the process and it goes straight through. If I have =7 files in the queue, conversion goes to ~20%, then gets stuck for 15 seconds, then continues again, always in "chunks" of a few % before getting stuck again. During the time the process is stuck, CPU is at 1%. RAM is not limiting, it is maybe at 70% or so and not going up. I don't get the same problem on other, even slower machines. The computer gets also stuck at 1% CPU doing nothing on other occasions, but for multithreading it is most frequent. Where should I look for the problem?

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• TortoiseSVN client slows Explorer to a crawl in Windows XP running in Parallels

  - by Cory Larson

  I thought I'd make my first SuperUser question relatively simple, though it's the kind of question that may not get many responses as I'm not directly involved with the issue. A colleague does his development in Windows XP running in Parallels on his Mac. We've just migrated our VSS repository to SVN, and we've gone with TortoiseSVN as our client of choice with the Ankhsvn plugin for Visual Studio. On his XP instance, after installing TortoiseSVN, browsing through folders using Explorer is extremely slow; about 15 - 30 seconds before the contents of the next folder displays. It's the slowest when opening My Computer. Once he reaches a folder that contains the working content of an SVN project, Explorer behaves quickly again as expected. It seems that TortoiseSVN may be spending a bunch of time searching subfolders for stuff so it can do its icon-overlay thing, but that's just a guess. I've used TortoiseSVN for years on both XP and Vista on far less powerful machines without any issues with Explorer, so I'm attributing the slowness to it being run in a VM, though that may not be the actual issue. So has anyone encountered similar performance issues, and/or know of a fix? Keep in mind that any requests to make changes to his configuration will need to be communicated and thus my response time might be slow. Thanks everyone!

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• What may the reason of slowness be (see details in message body)?

  - by Ivan

  I've got a really weird situation I'm beating to solve. A performance problem which looks really like an empty waiting sequence set in code (while it probably isn't so). I've got a pretty powerful dedicated server (10 GB RAM, eight Xeon cores, etc) running Ubuntu 10.04 with all the functionality services (except OpenVPN server used to provide secure access to clients) deployed in separate VirtualBox (vboxheadless) machines (one for the company e-mail server, one for web server and one for accounting/crm server (Firebird + proprietary app server working with Delphi-made clients)). CPU load (as "top" says) is almost always near zero. Host system RAM is close to 100% usage but not overloaded (as very little swapping gets used, and freed (by stopping one of VMs) memory doesn't get reused any quickly). Approximately 50% of guests RAM is used. iostat usually shows near zero %util. Network bandwidth seems to be underused. But the accounting/crm client (a Win32 Delphi application run on WinXP machines) software works hell-slow with this server (and works much better using an inside-LAN Windows server). I just can't imagine what can make it be slow if there are so plenty of CPU, RAM, HDD and bandwidth resources available on clients and on the server even in their hardest moments. Saying bandwidth is underused I not only know that clients and the server are connected to the Internet with a bigger channels than really used (which leaves the a chance they may have a bottleneck of a sort on the route between them), I've tested bandwidth between clients and the server by copying files among them.

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• how do you view / access the contents of a mounted dmg drive through TERMINAL hdiutil diskmount

  - by A. O.

  My external USB drive failed. I made a .dmg image file of the drive using disk utility. Later I was not able to mount the .dmg image. I used terminal hdiutil attach -noverify -nomount name.dmg diskutil list diskutil mountDisk /dev/disk4 then received the following message: Volume(s) mounted successfully However, I cant see the drive or access its contents through Finder. DUtility shows the drive as ghost but I still cant mount it using diskutility. Terminal tells me that the drive is mounted and constantly shows it in the diskutil list. pwd is not the mounted .dmg image. I dont know how to enter into the mounted image drive to see its contents. So in case what I said sounds like I see the files in the mounted image no this is not the case. I do not know how to access or even change the pwd within Terminal. I was hoping to see the mounted drive tru finder but I do not see that. So I need help as to how to find a way to access the mounted image drive if it was really mounted. Terminal says that it was and it shows it under diskutil list as a /dev/disk4. Can someone please help me access the files on this drive?

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• Linux RAID: Replacing Failed Drive...permanantly

  - by user137519

  Okay, odd question here. I have a server with RAID 5. A drive failed, in a really physically in a really odd way. On the machine it boots and is seen by the BIOS but...no partition can be seen on the drive consistantly (in and out). 2 out of 3 drives working...I made new spare disk and added it, RAID 5 rebuilt clean. All appears well but...when I reboot it keeps trying to use the 2nd drive which doesn't give any partition data, so of course the RAID 5 gets 2 out of 3...again. The status of my drive is as follows: /dev/sda2:Good /dev/sdb2 (drive has physical problem so no partition data) bad, /dev/sdc2:good /dev/sdd2:good. Every time I reboot the mdadm system seems to keep trying to use /dev/sdb which has physical failure (although spins and is detected). /dev/sdd is the new drive I created. I added /dev/sdd to the raid and it rebuilds the raid but this action isn't memorized upon reboot so it keeps listing /dev/sda and /dev/sdc but doesn't use the perfectly good /dev/sdd until I re-add manually. I've tried removing the dead drive with the mdadm tool, but as it cannot see /dev/sdb paritions it will not fail or remove it (says partition doesn't exist). the /etc/mdadm.conf was automatically made on the original OS install which only lists: DEVICE partitions MAILADDR root ARRAY /dev/md2 super-minor=2 ARRAY /dev/md0 super-minor=0 ARRAY /dev/md1 super-minor=1 Basically just the raids to use on boot. I need to remove this semi-dead drive (/dev/sdb) but I'd prefer to know why this is happening before I do. any ideas or suggestions. I supposed I could attempt to clone/replace /dev/sdb (the partitions on drive show up, then disappear shortly after) but given the partition "chester cat" behaviour this seems risky to me and as I have a working "spare" it seems unnecessary. Thanks in advance for your insight.

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• Upgrade or replace?

  - by Felix

  My current PC is about four years old, although I have made upgrades to it throughout its existence. The current specs are: (old) Intel Pentium D 2.80Ghz (32K L1 / 2M L2), Gigabyte 945GCMX-S2 motherboard (old) 2.5GB DDR2 (slot0: 512MB @ 533Mhz; slot1: 2GB @ 667Mhz) (new) HIS Radeon HD 4670 - I think this is limited by the motherboard not supporting PCIe 2.0 (?) (old) WD Caviar 160GB - pretty slow (new) WD Caviar Black 640GB (if any more specs are relevant, let me know and I'll add them) Now, on to my question. I've been having performance issues lately, both in video games and in intensive applications. A couple of examples: Android application development (running Eclipse and the Android emulator) is painfully slow (on Linux). I only realized this when, at my new job as an Android dev, both tools are MUCH quicker. (I'm not sure what CPU I have there) The guys at my new job got me NFS Hot Pursuit, in which I barely get like 5-10FPS, even with graphics options turned all the way down My guess is that the bottleneck in my system is my CPU, so I'm thinking of upgrading to a Quad Core i5 + new motherboard + 4GB DDR3 (or more, 'cause I know you'll all jump and say 8GB minimum). Now: Is that a good idea? Is my CPU really a bottleneck, or is the whole system too old and I should replace it? I run Windows 7 on the old, 160GB HDD (which is on IDE, by the way). Could this slow down games as well? Should I get a new drive for Windows if I want to play new games? I know nothing about power supplies. Could that be a problem / will it be a problem if I upgrade to an i5? How come DiRT2 works on full graphics settings (pretty amazing graphics by the way) and NFS Hot Pursuit pulls only 5-10FPS?

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• Best solution top keep data secure

  - by mrwooster

  What is the simplest and most elegant way of storing a small amount of data in a reasonably secure way? I am not looking for ridiculous levels of advanced encryption (AES-256 is more than enough) and I am only looking to encrypt a small number of files. The files I wish to encrypt are mostly comprised of password lists and SSH keys for servers. Unfortunately it is impossible to keep track of ever changing passwords for my servers (and SSH keys) and so need to keep a list of the passwords. Obviously this list needs to be secure, and also portable (I work from multiple locations). At the moment, I use a 10MB encrypted disk image on my mac (std .dmg AES-256) and just mount it whenever I need access to the data. To my knowledge this is very secure and I am very happy using it. However, the data is not very portable. I would like to be able to access my data from other machines (especially ones running linux), and I am aware that there are quite a few issues trying to mount an encrypted .dmg on linux. An alternative I have considered is to create a tar archive containing the files and use gpg --symmetric to encrypt it, but this is not a very elegant solution as it requires gpg to be installed on every system. So, what over solutions exist, and which ones would you consider to be the most elegant? Ty

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• How can I optimize my ajax calls to deliver at 60ms.

  - by Quintin Par

  I am building an autocomplete functionality for my site and the Google instant results are my benchmark. When I look at Google, the 50-60 ms response time baffle me. They look insane. In comparison here’s how mine looks like. To give you an idea my results are cached on the load balancer and served from a machine that has httpd slowstart and initcwnd fixed. My site is also behind cloudflare From a server side perspective I don’t think I can do anything more. Can someone help me take this 500 ms response time to 60ms? What more should I be doing to achieve Google level performance? Edit: People, you seemed to be angry that I did a comparison to Google and the question is very generic. Sorry about that. To rephrase: How can I bring down response time from 500 ms to 60 ms provided my server response time is just a fraction of ms. Assume the results are served from Nginx - Varnish with a cache hit. Here are some answers I would like to answer myself assume the response sizes remained more or less the same. Ensure results are http compressed Ensure SPDY if you are on https Ensure you have initcwnd set to 10 and disable slow start on linux machines. Etc. I don’t think I’ll end up with 60 ms at Google level but your collective expertise can help easily shave off a 100 ms and that’s a big win.

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• FDE / SSD - partition and leave some unencrypted?

  - by Web Design Hero

  Just bought a used beast of a desktop pc. The system drive is setup as a Raid 0 SSD (Intel 510 SSD Drives) with 128 each. I will probably not have to many programs beyond office and maybe Adobe CS if I spring for it, I will be keeping big data on a regular hdd. My question is about setting up TrueCrypt with my configuration. I have not previously done full disk encryption, but I feel that its probably a good idea. I have done some speed tests using file containers on the hdd and the sdd with truecrypt. While there is a huge hit with the SSDs and Truecrypt, it still outperforms the hdd on its own by a good margin, so I think i will be okay for my needs with truecrypt. I have seen in a few places that they recommend partitioning the drive and leavign some of the SSD not inside truecrypt, does this really make a difference? If so, how much should I leave? Will there be any issue in the Raid0 configuration? I am not really concerned about all the wear leveling issue, rather loose data and be secure, but since I don't need all that space neccesarily, I would like to optimize my setup for security and speed.

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• Can installing Linux or Grub make all of my operating systems slow?

  - by Geore Shg

  I installed Linux Mint 64-bit recently but it freezes up all the time. Not only that, but Grub wouldn't detect Windows. I thought it was just an issue with Linux Mint so I booted into Ubuntu - however that froze up as well. I downloaded Fedora to replace Linux Mint with, but that also freezes up. I finally gave up trying to repair Grub, burning a supergrub grub2 disk and using that to boot into Windows. Windows now freezes up as well. I installed a new copy of Windows on a different drive but to no avail. Right before all this started my computer was running very smoothly. I am wondering if the installation of Linux Mint, the reinstallation of Grub, or me messing with the BIOS (when I was attempting to repair Grub) could have done something drastic enough that everything is slow now? I realize that computers get gradually slower over time, but this was in no way gradual and it happened directly after the installation of Linux Mint. If so, what should I do?

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• Ubuntu 12.04 VirtualBox on powerful W7 quite slow

  - by wnstnsmth

  I own a Thinkpad T420s with 8GB RAM, 160 GB SSD and a quite fast i7 processor. Summa summarum a very fast computer that works perfectly. Now, I am not very impressed by the performance of my Ubuntu 12.04 virtual machine running on VirtualBox 4.1.18. I assume that Virtual Machines are always a bit slower than the guest system, still I think it should be more performant given the hardware settings I give it: 4096 MB RAM 1 CPU without CPU limitation (I would like to give it more but then it does not seem to work - I am not experienced in this maybe somebody could give me advice on this too) Activated PAE/NX, VT-x/AMD-V and Nested Paging 96 MB Graphics Memory (no 2D or 3D acceleration) ~ 14 GB disk space, currently about 7 GB are used Maybe I misconfigured something, could you give me a hint please? Thanks! Edit: What I mean by slow is that for example switching tabs in the browser (whether FF or Chrome) only goes with a 0.5s delay or something, as well as switching application windows and/or double-clicking applications in the dock to get all open windows.. opening Aptana takes about a minute whereas opening something like Photoshop on the guest system takes 5 seconds

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• New i7 is slower than old Core 2 Duo? Why? (BIOS programming)

  - by DrChase

  I've always wondered why the companies who make BIOS' either have terrible engineering psychologists or none at all. But without wasting your time further with random speculative questions, my real question is as follows: Why does my new computer run slower than my old computer? Old Computer: Intel Core 2 Duo CPU @ 3.0 Ghz (stock) 4GB OCZ DDR2 800 RAM Wolfdale E8400 mb nVidia GeForce 8600 GT New Computer: Intel Core i7 920 @ ~3.2 Ghz 6 GB OCZ DDR3 1066 RAM EVGA x58 SLI LE motherboard nVidia GeForce GTX 275 Vista x64 Home Premium on both. "Run slower" is defined as: - poorer FPS performance in the same games, applications - takes longer to start up - general desktop usage (checking email, opening up files, running exe's) is noticeably slower At first I thought I must've not set something up in the BIOS or something. But I have no idea how to set anything in the bios except for "Dummy O.C.", which brought me to ~3.2 Ghz. But beyond that I have no idea. I've been reading stuff about "ram timing" and voltages and the like but I really have no idea about that stuff. I'm a psychologist who has a basic understanding in building his own computers, not a computer scientist. Can someone give me some wisdom that might guide me to the reason my new computer is worse than my older one? I'm sorry if this is a bad question, or not appropriate to SO. I'm just pretty frustrated now and you all have helped me in the past so I figured I'd give it a shot. Thanks for your time.

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• Growing a small hosting company [closed]

  - by user2353007

  We currently have a few servers, 1 WHM VPS (2GB), 1 MS SQL VPS (2 GB), and 1 IIS VPS (2GB). The VPS servers are doing fine as far as uptime and response times but we would like to add the following features. 1) monitoring with load statistics 2) failover I have looked a Zabbix, Zenoss, Nagios, and a couple of other cloud solutions like monitor.us and watchdog from Zerigo. Ideally for the monitoring solution. Our current hosting company suggested we get a dedicated server or VPS and install load balancing software (not sure I like that idea). I've looked into Rackspace and Amazon load balancers which seem like the most feasible solutions for load balancers. Does anybody have any input on the monitoring and load balancing products I'm looking into? Monitoring should monitor uptime as well as give reports on memory usage, disk usage, processor usage, and which processes/websites/users are responsible for the load. It would be ideal if the load balancer worked with any IP. Not sure if either Rackspace or Amazon load balancers would allow load balancing with servers outside their datacenter. Thank you.

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• moving from WinXP to WinServer in VmWare

  - by Alex

  I have a Vmware machine for.Net application testing. Current setup: Host OS: win7 Guest OS: Right now the guest OS is Win Xp Pro x64, which runs great with just 1 gigabyte of RAM and 10 gigs of disk space. * This part can be skipped * As I said, there was a program that I needed to test, but unfortunately, by default, Vmware installs crappy display drivers(called SVGA II) on XP machines and there is NO way to upgrade them! This resulted in my program's error (the program used SlimDX (DirectX wrapper) to do some stuff..). Eventually I found out that display drivers most certainly is the problem. For example, Windows 7 virtual machine uses SVGA 3D drivers and I have NO problems running my SlimDX-based program. Now, regarding Windows Server 2008! Apparently, WDDM driver is supported by WS2008, which means that I'll be able to install SVGA 3D and to test my DX apps. * end of skip * The questions are: Will WS2008 be as smooth with just 1 gig of RAM just like Win XP was? Will 10 gigs of HDD be enough? Or the server requires more? Will I be able to install .Net ver. 4 on WS2008? Are there any limitations that I need to be aware of as a .Net programmer? EDIT: I was hoping that WS2008 is XP-based, not Vista-vased/W7-based. In comparison, W7 virtual machine with 2 gigs of RAM and 2 proc cores nearly kills my Host OS. Whereas, WinXp runs extremely fast even with 1 core and 1 gig of RAM. That's the main reason why I want to try WS2008..

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• Comparing 128MB GeForce 8600GT and 512MB Radeon X1650

  - by Synetech inc.

  Hi, I'm trying to determine which is the better of these two video cards: 128MB Nvidia GeForce 8600GT card while the other has a 512MB ATI Radeon X1650 card. Both cards are the upper-level mid-range versions of their respective series. On the one hand, the ATI has substantially more VRAM, but the Nvidia supports D3D 10 and SM4.0 as opposed to D3D 9.0c/SM3.0 that the ATI supports. Also, I have always heard better things about Nvidia cards compared to ATI cards. I'm trying to find some advice on which one is better, but I can't find any actual comparisons or anything for these specific cards (the comparisons I can find are only similar ones like the X1650 Pro or 8600GT PCI-E), so I figure that what I need to know is whether the extra VRAM is that important. Looking at the ATI table and the Nvidia table seems to indicate that the Nvidia is better, but then again, the Nvidia table also says that the GeForce 8600GT is a PCI-E card with at least 256MB even though the card in question is an AGP with 128MB. (:-?) (It looks like the ATI card is not supported in Windows 7 while the Nvidia card is, which I suppose is also a factor, though not quite as immediately relevant as performance.) Any ideas? Thanks a lot.

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• How to access files on a USB-connected NTFS disk removed from a Win7 notebook?

  - by yosh m

  My daughter seems to have fried her motherboard in her Lenovo Notebook. The disk seems to be fine. I removed the disk and used a universal disk-to-USB kit to attach it to another computer. The disk is recognized fine and I can peruse it in Windows Explorer. The problem is that the files she would like to recover from it are located in places that Windows refuses to let me access. When I try, for example, to enter the directory "Documents and Settings" it gives me an "Access is denied" error. Same thing when I try to go into the various User directories and other locations. I thought to try creating a Ghost image & retrieve the files from that, but Ghost seems to croak when I try to run it - apparently it doesn't like accessing the disk via a USB connection (even though I've told it to install the drivers for USB). Any other ideas about how to get to the files I need, either through Windows or perhaps some other OS that I could boot from a CD that can read an NTFS disk? Thanks, Yosh

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• MySQL performance

  - by kapil.israni

  Hi, I have this LAMP application with about 900k rows in MySQL and I am having some performance issues. Background - Apart from the LAMP stack , there's also a Java process (multi-threaded) that runs in its own JVM. So together with LAMP & java, they form the complete solution. The java process is responsible for inserts/updates and few selects as well. These inserts/updates are usually in bulk/batch, anywhere between 5-150 rows. The PHP front-end code only does SELECT's. Issue - the PHP/SELECT queries become very slow when the java process is running. When the java process is stopped, SELECT's perform alright. I mean the performance difference is huge. When the java process is running, any action performed on the php front-end results in 80% and more CPU usage for mysqld process. Any help would be appreciated. MySQL is running with default parameters & settings. Software stack - Apache - 2.2.x MySQL -5.1.37-1ubuntu5 PHP - 5.2.10 Java - 1.6.0_15 OS - Ubuntu 9.10 (karmic)

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• jQuery performance

  - by jAndy

  Hi Folks, imagine you have to do DOM manipulation like a lot (in my case, it's kind of a dynamic list). Look at this example: var $buffer = $('<ul/>', { 'class': '.custom-example', 'css': { 'position': 'absolute', 'top': '500px' } }); $.each(pages[pindex], function(i, v){ $buffer.append(v); }); $buffer.insertAfter($root); "pages" is an array which holds LI elements as jQuery object. "$root" is an UL element What happens after this code is, both UL's are animated (scrolling) and finally, within the callback of animate this code is executed: $root.detach(); $root = $buffer; $root.css('top', '0px'); $buffer = null; This works very well, the only thing I'm pi**ed off is the performance. I do cache all DOM elements I'm laying a hand on. Without looking too deep into jQuery's source code, is there a chance that my performance issues are located there? Does jQuery use DocumentFragments to append things? If you create a new DOM element with var new = $('<div/>') it is only stored in memory at this point isnt it?

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• WF performance with new 20,000 persisted workflow instances each month

  - by Nikola Stjelja

  Windows Workflow Foundation has a problem that is slow when doing WF instances persistace. I'm planning to do a project whose bussiness layer will be based on WF exposed WCF services. The project will have 20,000 new workflow instances created each month, each instance could take up to 2 months to finish. What I was lead to belive that given WF slownes when doing peristance my given problem would be unattainable given performance reasons. I have the following questions: Is this true? Will my performance be crap with that load(given WF persitance speed limitations) How can I solve the problem? We currently have two possible solutions: 1. Each new buisiness process request(e.g. Give me a new drivers license) will be a new WF instance, and the number of persistance operations will be limited by forwarding all status request operations to saved state values in a separate database. 2. Have only a small amount of Workflow Instances up at any give time, without any persistance ofso ever(only in case of system crashes etc.), by breaking each workflow stap in to a separate worklof and that workflow handling each business process request instance in the system that is at that current step(e.g. I'm submitting my driver license reques form, which is step one... we have 100 cases of that, and my step one workflow will handle every case simultaneusly). I'm very insterested in solution for that problem. If you want to discuss that problem pleas be free to mail me at [email protected]

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• Figuring out the Nyquist performance limitation of an ADC on an example PIC microcontroller

  - by AKE

  I'm spec-ing the suitability of a dsPIC microcontroller for an analog-to-digital application. This would be preferable to using dedicated A/D chips and a separate dedicated DSP chip. To do that, I've had to run through some computations, pulling the relevant parameters from the datasheets. I'm not sure I've got it right -- would appreciate a check! (EDITED NOTE: The PIC10F220 in the example below was selected ONLY to walk through a simple example to check that I'm interpreting Tacq, Fosc, TAD, and divisor correctly in working through this sort of Nyquist analysis. The actual chips I'm considering for the design are the dsPIC33FJ128MC804 (with 16b A/D) or dsPIC30F3014 (with 12b A/D).) A simple example: PIC10F220 is the simplest possible PIC with an ADC Runs at clock speed of 8MHz. Has an instruction cycle of 0.5us (4 clock steps per instruction) So: Taking Tacq = 6.06 us (acquisition time for ADC, assume chip temp. = 50*C) [datasheet p34] Taking Fosc = 8MHz (? clock speed) Taking divisor = 4 (4 clock steps per CPU instruction) This gives TAD = 0.5us (TAD = 1/(Fosc/divisor) ) Conversion time is 13*TAD [datasheet p31] This gives conversion time 6.5us ADC duration is then 12.56 us [? Tacq + 13*TAD] Assuming at least 2 instructions for load/store: This is another 1 us [0.5 us per instruction] Which would give max sampling rate of 73.7 ksps (1/13.56) Supposing 8 more instructions for real-time processing: This is another 4 us Thus, total ADC/handling time = 17.56us (12.56us + 1us + 4us) So expected upper sampling rate is 56.9 ksps. Nyquist frequency for this sampling rate is therefore 28 kHz. If this is right, it suggests the (theoretical) performance suitability of this chip's A/D is for signals that are bandlimited to 28 kHz. Is this a correct interpretation of the information given in the data sheet in obtaining the Nyquist performance limit? Any opinions on the noise susceptibility of ADCs in PIC / dsPIC chips would be much appreciated! AKE

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• Naming multi-instance performance counters in .NET

  - by Roger Lipscombe

  Most multiple instance performance counters in Windows seem to automatically(?) have a #n on the end if there's more than one instance with the same name. For example: if, in Perfmon, you look under the Process category, you'll see: ... dwm explorer explorer#1 ... I have two explorer.exe processes, so the second counter has #1 appended to its name. When I attempt to do this in a .NET application: I can create the category, and register the instance (using the PerformanceCounterCategory.Create that takes a CounterCreationDataCollection). I can open the counter for write and write to it. When I open the counter a second time, it opens the same counter. This means that I have two applications fighting over the counters. The documentation for PerformanceCounter.InstanceName states that # is not allowed in the name. So: how do I have multiple-instance performance counters that are actually multiple instance? And where the second (and subsequent) instances get #n appended to the name? That is: I know that I can put the process ID (e.g.) on the instance name. This works, but has the unfortunate side effect that restarting the process results in a new PID, and Perfmon continues monitoring the old counter.

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• Improving the performance of XSL

  - by Rachel

  I am using the below XSL 2.0 code to find the ids of the text nodes that contains the list of indices that i give as input. the code works perfectly but in terms for performance it is taking a long time for huge files. Even for huge files if the index values are small then the result is quick in few ms. I am using saxon9he Java processor to execute the XSL. <xsl:variable name="insert-data" as="element(data)*"> <xsl:for-each-group select="doc($insert-file)/insert-data/data" group-by="xsd:integer(@index)"> <xsl:sort select="current-grouping-key()"/> <data index="{current-grouping-key()}" text-id="{generate-id( $main-root/descendant::text()[ sum((preceding::text(), .)/string-length(.)) ge current-grouping-key() ][1] )}"> <xsl:copy-of select="current-group()/node()"/> </data> </xsl:for-each-group> </xsl:variable> In the above solution if the index value is too huge say 270962 then the time taken for the XSL to execute is 83427ms. In huge files if the index value is huge say 4605415, 4605431 it takes several minutes to execute. Seems the computation of the variable "insert-data" takes time though it is a global variable and computed only once. Should the XSL be addessed or the processor? How can i improve the performance of the XSL.

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• APplication performance issue : SqlServer & Oracle

  - by Mahesh

  Hi, We have a applicaiton in Silverlight,WCF, NHibernate. Currently it is supporting SQL Serve and Oracle database. As it's huge data, it is running ok on SQL Sevrer. But on Oracle it is running very slow. For one functionality it takes 5 Sec to execute on SQL Server and 30 Sec on Oracle. I am not able to figure out what will be issue. Two things that i want to share with you about our database. 1) Database: contains one base table contains column of type SQLServer: [Text] Oracle: [NCLOB] 2) Our database structure is too much normalized. May be in the oracle i have used NCLOB, that is the cause of the performance. I mean i don't know the details about it.... Can anyone please let me know what will be cause? Or Which actions do i need to follw to improve the performance as equal as SqlServer.? Thanks in advance. Mahesh.

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• How can I determine PerlLogHandler performance impact?

  - by Timmy

  I want to create a custom Apache2 log handler, and the template that is found on the apache site is: #file:MyApache2/LogPerUser.pm #--------------------------- package MyApache2::LogPerUser; use strict; use warnings; use Apache2::RequestRec (); use Apache2::Connection (); use Fcntl qw(:flock); use File::Spec::Functions qw(catfile); use Apache2::Const -compile => qw(OK DECLINED); sub handler { my $r = shift; my ($username) = $r->uri =~ m|^/~([^/]+)|; return Apache2::Const::DECLINED unless defined $username; my $entry = sprintf qq(%s [%s] "%s" %d %d\n), $r->connection->remote_ip, scalar(localtime), $r->uri, $r->status, $r->bytes_sent; my $log_path = catfile Apache2::ServerUtil::server_root, "logs", "$username.log"; open my $fh, ">>$log_path" or die "can't open $log_path: $!"; flock $fh, LOCK_EX; print $fh $entry; close $fh; return Apache2::Const::OK; } 1; What is the performance cost of the flocks? Is this logging process done in parallel, or in serial with the HTTP request? In parallel the performance would not matter as much, but I wouldn't want the user to wait another split second to add something like this.

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