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• Tuning MySQL to take advantage of a 4GB VPS

  - by alistair.mp

  Hello, We're running a large site at the moment which has a dedicated VPS for it's database server which is running MySQL and nothing else. At the moment all four CPU cores are running at close to 100% all of the time but the memory usage sticks at around 268MB out of an available 4096MB. I'm wondering what we can do to better utilise the memory and reduce the CPU load by tweaking MySQL's settings? Here is what we currently have in my.cnf: http://pastie.org/private/hxeji9o8n3u9up9mvtinbq Thanks

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• General confusion with assembler

  - by gnrlcf

  So I took a look at the x86 assembly language; All the commands are pretty clear but: I don't see anything that can actually trigger something in the computer like: Access RAM and not only CPU registers, read from the HDD, etc. How do you go beyond computations in the CPU with assembler?

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• When should a uniform be used in shader programming?

  - by Phineas

  In a vertex shader, I calculate a vector using only uniforms. Therefore, the outcome of this calculation is the same for all instantiations of the vertex shader. Should I just do this calculation on the CPU and upload it as a uniform? What if I have ten such calculations? If I upload a lot of uniforms in this way, does CPU-GPU communication ever get so slow that recomputing such values in the vertex shader is actually faster?

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• Which type of design pattern should be used to create an emulator?

  - by Facon

  I have programmed an emulator, but I have some doubts about how to organizate it properly, because, I see that it has some problems about classes connection (CPU <- Machine Board). For example: I/O ports, interruptions, communication between two or more CPU, etc. I need for the emulator to has the best performance and good understanding of the code. PD: Sorry for my bad English. EDITED: Asking for multiple patterns.

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• stop execution of process for miliseconds.

  - by Viral

  hi friends, I m creating a Tic tac toe game, in that after click made by user automatically the cpu will respond. I want the cpu response after 0.50 seconds, the sleep() function takes too many time, i don't want that much time, is there any other way to do so???

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• Java Socket Connection is flooding network OR resulting in high ping

  - by user1461100

  i have a little problem with my java socket code. I'm writing an android client application which is sending data to a java multithreaded socket server on my pc through direct(!) wireless connection. It works fine but i want to improve it for mobile applications as it is very power consuming by now. When i remove two special lines in my code, the cpu usage of my mobile device (htc one x) is totally okay but then my connection seems to have high ping rates or something like that... Here is a server code snippet where i receive the clients data: while(true) { try { .... Object obj = in.readObject(); if(obj != null) { Class clazz = obj.getClass(); String className = clazz.getName(); if(className.equals("java.lang.String")) { String cmd = (String)obj; if(cmd.equals("dc")) { System.out.println("Client "+id+" disconnected!"); Server.connectedClients[id-1] = false; break; } if(cmd.substring(0,1).equals("!")) { robot.keyRelease(PlayerEnum.getKey(cmd,id)); } else { robot.keyPress(PlayerEnum.getKey(cmd,id)); } } } } catch .... Heres the client part, where i send my data in a while loop: private void networking() { try { if(client != null) { .... out.writeObject(sendQueue.poll()); .... } } catch .... when i write it this why, i send data everytime the while loop gets executed.. when sendQueue is empty, a null "Object" will be send. this results in "high" network traffic and in "high" cpu usage. BUT: all send comments are received nearly immediately. when i change the code to following: while(true) ... if(sendQueue.peek() != null) { out.writeObject(sendQueue.poll()); } ... the cpu usage is totally okay but i'm getting some laggs.. the commands do not arrive fast enough.. as i said, it works fine (besides cpu usage) if i'm sending data(with that null objects) every while execution. but i'm sure that this is very rough coding style because i'm kind of flooding the network. any hints? what am i doing wrong?? Thanks for your Help! Sincerly yours, maaft

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• Microsoft Sharepoint Error

  - by Azra

  hi I am getting the Following Error Could not load file or assembly 'Microsoft.SharePoint.Search, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c' or one of its dependencies. An attempt was made to load a program with an incorrect format, Though I have added the required Share point refernece and also modified the project setting , set the CPU as Any CPU. still the error is coming. kindly help

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• WPF: Improving Performance for Running on Older PCs

  - by Phil Sandler

  So, I'm building a WPF app and did a test deployment today, and found that it performed pretty poorly. I was surprised, as we are really not doing much in the way of visual effects or animations. I deployed on two machines: the fastest and the slowest that will need to run the application (the slowest PC has an Intel Celeron 1.80GHz with 2GB RAM). The application ran pretty well on the faster machine, but was choppy on the slower machine. And when I say "choppy", I mean the cursor jumped even just passing it over any open window of the app that had focus. I opened the Task Manager Performance window, and could see that the CPU usage jumped whenever the app had focus and the cursor was moving over it. If I gave focus to another (e.g. Excel), the CPU usage went back down after a second. This happened on both machines, but the choppiness was only noticeable on the slower machine. I had very limited time to tinker on the deployment machines, so didn't do a lot of detailed testing. The app runs fine on my development machine, but I also see the CPU spiking up to 10% there, just running the cursor over the window. I downloaded the WPF performance tool from MS and have been tinkering with it (on my dev machine). The docs say this about the "Frame Rate" metric in the Perforator tool: For applications without animation, this value should be near 0. The app is not doing any heavy animation, but the frame rate stays near 50 when the cursor is over any window. The screens I tested on have column headers in a grid that "highlight" and buttons that change color and appearance when scrolled over. Even moving the mouse on blank areas of the windows cause the same Frame rate and CPU usage (doesn't seem to be related to these minor animations). (Also, I am unable to figure out how to get anything but the two default tools--Perforator and Visual Profiler--installed into the WPF performance tool. That is probably a separate question). I also have Redgate's profiling tool, but I'm not sure if that can shed any light on rendering performance. So, I realize this is not an easy thing to troubleshoot without specifics or sample code (which I can't post). My questions are: What are some general things to look for (or avoid) in the code to improve performance? What steps can I take using the WPF performance tool to narrow down the problem? Is the PC spec listed above (Intel Celeron 1.80GHz with 2GB RAM) too slow to be running even vanilla WPF applications?

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• Which design pattern should be used to create an emulator?

  - by Facon

  I have programmed an emulator, but I have some doubts about how to organizate it properly, because, I see that it has some problems about classes connection (CPU <- Machine Board). For example: I/O ports, interruptions, communication between two or more CPU, etc. I need for the emulator to has the best performance and good understanding of the code. PD: Sorry for my bad English. EDITED - Asking for multiple patterns.

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• What design pattern should be used to create an emulator?

  - by Facon

  I have programmed an emulator, but I have some doubts about how to organizate it properly, because, I see that it has some problems about classes connection (CPU <- Machine Board). For example: I/O ports, interruptions, communication between two or more CPU, etc. I need for the emulator to has the best performance and good understanding of the code. PD: Sorry for my bad English.

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• Is there a way to force the JVM to run on a single processor or Core.

  - by richs

  In Java, is there a way to force a JVM instance to run on a single CPU/Core. Additionally is there a way for given thread to figure out what CPU it is running on?

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• Do graphic cards have instruction sets of their own?

  - by Matt

  Do graphic cards have instruction sets of their own? I assume they do, but I have been wondering if it is proprietary or if there is some sort of open standard. Is every GPU instruction preceded by a CPU instruction or is it seamless? That is does OpenGL or DirectX call on the driver layer via the CPU which then sends a GPU instruction down the bus or is it more elaborate.

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• Utilizing 5 physical servers in 1 cluster

  - by Vijay Gharge

  Hi all, I have 5 physical servers with low end memory & cpu resources. I want to create 1 cluster using all these servers and want to run mysql db on the same such that mysql db would utilize 5 server's CPU power to execute db queries & same for memory. Could you please help me understanding how to achieve this? Regards,

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• Could not load file or assembly ... or one of its dependencies. An attempt was made to load a progra

  - by Dan

  I am getting the following error message when compiling or attempting to run my application on Windows 7 64 bit. I've scoured the internet and many people have the same error message however none of the solutions address my problem or situation. Using VS 2010. Error 38 Could not load file or assembly 'file:///D:/Projects/Windows Projects/Weld/Components/FileAttachments/FileAttachments/FileAttachments/bin/x86/Debug/FileAttaching.dll' or one of its dependencies. An attempt was made to load a program with an incorrect format. Line 1212, position 5. D:\Projects\Windows Projects\Weld\Weld\Weld.UI\frmMain.resx 1212 5 Weld.UI Ok, so I have 2 projects a UI project and a FileAttachment project. UI project has a reference to FileAttachment project. When I compile UI project in "Any CPU" mode everything works fine and it runs. I assume 'Any CPU' will run in 64bit mode when I compile as that is the platform I am using. I want to run/compile as x86 so I try to do that, so I change configuration for all projects to x86 and verify that these configurations are compiling to x86. I compile and get the error as stated above. I find it odd that it compiles and works fine in 64bit but not 32bit. However when compiled and deployed to users as 'Any CPU', if these users have x86 it still works for them no problem. I just can't compile or run as x86 on my PC. Again, I can compile as Any CPU and deploy to a 32bit PC no problem. Neither project are referencing any 64bit only dlls. Both projects are verified to be targetting 32bit dll's and .NET Framework assemblies. I need to compile and run this locally under 32bit mode. I need JIT edit/continue among other things. Here is the line of code in the resx file that is causing the problem: </data> <data name="Appearance17.Image" type="System.Drawing.Bitmap, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64"> <value> The resx file is verified to be generated for .NET 2.0 amnd is only referencing .NET 2.0 assemblies and not .NET 4.0 versions. Any ideas here? I've searched the net and have found hundreds of people with the same error message but a different problem.

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• Determining the word width in C

  - by das_weezul

  Hi! I'm learning C right now and so I'm fiddling about with pointers. Is there a way to determine the word width of the CPU in C because I'm writing a small program which prints it's own stack (Because I'm curious how it is structured), so that information would come in handy. Right now I'm using an int pointer, as an integer is 4 Bytes wide and I'm using a 32-bit Intel Atom CPU. Thanks in advance, C gurus ;o)

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• function to profile / performance test PHP functions?

  - by Haroldo

  I'm not experiencing any performance issues, however I'd like to take a look at what takes how long and how much memory cpu it uses etc. I'd like to get a firsthand understanding of which things can be bottle necks etc and improve any code i might reuse or build upon... (perfectionist) I'm looking to create a litte function that i can call at the begining and end of each function that records: execution time memory used cpu demand any ideas?

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• Get gprof to profile based on wall-clock time?

  - by jetwolf

  My understanding is that by default gprof takes into account CPU time. Is there a way to get it to profile based on wall-clock time? My program does a lot of disk i/o, so the CPU time it uses only represents a fraction of the actual execution time. I need to know which portions of the disk i/o take up the most time.

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• Why does the first access to a JSP file take longer on the Google App Engine?

  - by Spines

  Here is my test: I access a servlet to get the JVM to load (absorb the loading request). Then i access a JSP that has <%= 5+7 %> in it and nothing else. The first access to this JSP uses 350ms of CPU time and has latency of 200ms. Subsequent accesses only have latency and cpu time of about 20ms. Why does the first access to the jsp after starting the servlet container take longer?

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• Do the changes to cpumask using sched_setaffinity() take place immediately

  - by Sukanto

  I am writing a linux kernel module that needs to pin two threads on two different cpus. I am planning to use sched_setaffinity() after exporting it in the kernel. Is there any other exported function for the same ? Also, if I set only 1 CPU in the cpumask, will the thread be moved to that cpu with immediate effect ? If not, how do I enforce the same ? Will it help to call schedule() just after sched_setaffinity() ?

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• How to diagnose computer lockup/freezing problem

  - by Scott Mitchell

  I built a desktop computer a couple years back with the following specs: CPU: Intel Core 2 Quad Q9300 Yorkfield 2.5GHz 6MB L2 Cache LGA 775 95W Quad-Core Processor BX80580Q9300 Motherboard: EVGA 122-CK-NF68-T1 LGA 775 NVIDIA nForce 680i SLI ATX Intel Motherboard Video Card: Two EVGA 256-P2-N758-TR GeForce 8600GT SCC 256MB 128-bit GDDR3 PCI Express x16 SLI Supported Video Card PSU: SeaSonic S12 Energy Plus SS-550HT 550W ATX12V V2.3 / EPS12V V2.91 SLI Certified CrossFire Ready 80 PLUS Certified Active PFC Power Supply Memory: Two G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model F2-6400CL5D-4GBPQ Since its inception, the machine has periodically locked up, the regularlity having varied over the years from once a day to once a month. Typically, lockups happen once every few days. By "lockup" I mean my computer just freezes. The screen locks up, I can't move the mouse. Hitting keys on my keyboard that normally turn LEDs on or off on the keyboard (such as Caps Lock) no longer turn the LEDs on or off. If there was music playing at the time of the lockup, noise keeps coming out of the speakers, but it's just the current frequency/note that plays indefinitely. There is no BSOD. When such a lockup occurs I have to do a hard reboot by either turning off the computer or hitting the reset button. I have the most recent version of the NVIDIA hardware drivers, and update them semi-regularly, but that hasn't seemed to help. I am currently using Windows 7 x64, but was previously using Windows Server 2003 x64 and having the same lockup issues. My guess is that it's somehow video driver or motherboard related, but I don't know how to go about diagnosing this problem to narrow down which of the two is the culprit. Additional information re: cooling Regarding cooling... I've not installed any after-market cooling systems aside from two regular fans I scavenged from an older computer. The fan atop the CPU is the one that shipped with it. One of the two scavenged fans I added it located at the bottom tower of the corner, in an attempt to create some airflow from front to back. The second fan is pointed directly at the two video cards. SpeedFan installation and readings Per studiohack's suggestion, I installed SpeedFan, which provided the following temperature readings: GPU: 63C GPU: 65C System: 76C CPU: 64C AUX: 36C Core 0: 78C Core 1: 76C Core 2: 79C Core 3: 79C Update #3: Another Lockup :-( Well, I had another lockup last night. :-( SpeedFan reported the CPU temp at 38 C when it happened, and there was no spike in temperature leading up to the freeze. One thing I notice is that the freeze seems more likely to happen if I am watching a video. In fact, of the last 5 freezes over the past month, 4 of them have been while watching a video on Flickr. Not necessarily the same video, but a video nevertheless. I don't know if this is just coincidence or if it means anything. (As an aside, each night before bedtime my 2 year old daughter sits on my lap and watches some home videos on Flickr and, in the last month, has learned the phrase, "Uh oh, computer broke.") Update #4: MemTest86 and 3DMark06 Test Results: Per suggestions in the comments, I ran the MemTest86 overnight and it cycled through the 8 GB of memory 5 times without error. I also ran the 3DMark06 test without a problem (see my scores at http://3dmark.com/3dm06/15163549). So... what now? :-) Any further suggestions on what to check? Is there some way to get a stack trace or something when the computer locks like that? Thanks

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• Is it possible to repair a Cisco 3500 XL (3548) switch with POST Error messages?

  - by Alex

  I've got an old Cisco 3500 XL, and it seems to have hardware issues. I've loaded the latest IOS and cleared all config. Does anyone have any experience fixing the switch core? I'm a reasonably competent SMD solderer, can I replace/reflow some chips? I've checked the power supply voltages and it's all within tolerance, and no visible signs of any component damage. Some chips are hot to the touch. I understand that these were EOL as of 2007, but should have a lifetime warranty for the electronics. I don't have a Cisco support contract, so I can't file a ticket. What should I do? Console output: switch: dir flash: Directory of flash:/ 2 -rwx 1811584 <date> c3500xl-c3h2s-mz.120-5.WC17.bin 1799680 bytes available (1812992 bytes used) switch: boot Loading "flash:c3500xl-c3h2s-mz.120-5.WC17.bin"...################################################################################################################################################################################### File "flash:c3500xl-c3h2s-mz.120-5.WC17.bin" uncompressed and installed, entry point: 0x3000 executing... Restricted Rights Legend Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph (c) of the Commercial Computer Software - Restricted Rights clause at FAR sec. 52.227-19 and subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software clause at DFARS sec. 252.227-7013. cisco Systems, Inc. 170 West Tasman Drive San Jose, California 95134-1706 Cisco Internetwork Operating System Software IOS (tm) C3500XL Software (C3500XL-C3H2S-M), Version 12.0(5)WC17, RELEASE SOFTWARE (fc1) Copyright (c) 1986-2007 by cisco Systems, Inc. Compiled Tue 13-Feb-07 15:04 by antonino Image text-base: 0x00003000, data-base: 0x00352924 Initializing C3500XL flash... flashfs[1]: 1 files, 1 directories flashfs[1]: 0 orphaned files, 0 orphaned directories flashfs[1]: Total bytes: 3612672 flashfs[1]: Bytes used: 1812992 flashfs[1]: Bytes available: 1799680 flashfs[1]: flashfs fsck took 3 seconds. flashfs[1]: Initialization complete. ...done Initializing C3500XL flash. C3500XL POST: System Board Test: Passed C3500XL POST: Daughter Card Test: Passed C3500XL POST: CPU Buffer Test: Passed C3500XL POST: CPU Notify RAM Test: Passed C3500XL POST: CPU Interface Test: Passed C3500XL POST: Testing Switch Core: Passed Error with Switch Core BIST test Phase 0. Returns: Test Complete Low : 0x0FFFFFFF, Test Complete High : 0xFFFFFFFE Test Phase Low : 0x00000040, Test Phase High : 0x00000000 Test Phase Third : 0x00000000, Test Complete Third : 0x000001F8 C3500XL POST FAILURE: Testing Switch Core: Failed C3500XL POST FAILURE: Testing Buffer Table: Failed C3500XL POST FAILURE: Data Buffer Test: Failed C3500XL POST FAILURE: Configuring Switch Parameters: Failed C3500XL POST FAILURE: Switch Core BIST failed. C3500XL POST FAILURE: Cannot test Modules due to failure of Switch Core POST Del Mar Failure (0th Del Mar): req system failed to init C3500XL POST FAILURE: C3500XL POST FAILURE: ATM: required system failed to init C3500XL POST: Ethernet Controller Test: Passed C3500XL POST FAILURE: MII Test: Failed C3500XL POST FAILURE: Error waiting for Ethernet Controller and SW_PARAMS C3500XL POST FAILURE: Initialization/POST failed C3500XL POST FAILURE: AT: Failing because system POST failed Exception (8192)! Debug Exception (Could be NULL pointer dereference) CPU Register Context: Vector = 0x00002000 PC = 0x000F36F4 MSR = 0x00029200 CR = 0x22000024 LR = 0x000F6964 CTR = 0x001DE46C XER = 0x00000000 R0 = 0x00000000 R1 = 0x004E2580 R2 = 0x00000000 R3 = 0x00000000 R4 = 0x00000001 R5 = 0x00000000 R6 = 0x004E2718 R7 = 0x004E2718 R8 = 0x00000008 R9 = 0x00000000 R10 = 0x0000FFFF R11 = 0x00480000 R12 = 0x42000024 R13 = 0x00000000 R14 = 0x00000000 R15 = 0x00000000 R16 = 0x00000000 R17 = 0x00000000 R18 = 0x00000000 R19 = 0x00000000 R20 = 0x00000000 R21 = 0x00000000 R22 = 0x00000000 R23 = 0x00000000 R24 = 0x00000000 R25 = 0x00000020 R26 = 0x004E2718 R27 = 0x004E2718 R28 = 0x00000020 R29 = 0x00002513 R30 = 0x00000001 R31 = 0x00000000 Stack trace: PC = 0x000F36F4, SP = 0x004E2580 Frame 00: SP = 0x004E25A0 PC = 0x40000016 Frame 01: SP = 0x004E2618 PC = 0x000F6964 Frame 02: SP = 0x004E26A8 PC = 0x000F76DC Frame 03: SP = 0x004E26C8 PC = 0x000E8114 Frame 04: SP = 0x004E26F0 PC = 0x001F5BF8 Frame 05: SP = 0x004E2710 PC = 0x001F5CF4 Frame 06: SP = 0x004E2748 PC = 0x0023F4DC Frame 07: SP = 0x004E2750 PC = 0x0023E650 Frame 08: SP = 0x004E27C8 PC = 0x0023E89C Frame 09: SP = 0x004E27E0 PC = 0x0028AF34 Frame 10: SP = 0x004E27E8 PC = 0x001E38F8 Frame 11: SP = 0x004E2808 PC = 0x001E39A8 Frame 12: SP = 0x004E2820 PC = 0x0014E220 Frame 13: SP = 0x004E28C8 PC = 0x0014E39C Frame 14: SP = 0x00000000 PC = 0x001EB510

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• Why would VMWare to go defunct? How to recover from/prevent it?

  - by Josh

  I am running VMWare Server 2.0.2 (Build 203138) on a dual core Intel i5 with Ubuntu Server 10.04 LTS system (kernel 2.6.32-22-server #33-Ubuntu SMP). Disk Subsystem is a software RAID5 array. The system has been set up for a little over a week. For the past 5 days I have been running at leat 3 VMs (Linux and a variety of Windows OSes) with no issues whatsoever. But while I was installing Linux onto a new VM, suddenly all VMs became unresponsive, including the one I was installing to. I could not log in to the VMWare Management Interface, and the system was somewhat unresponsive via SSH. When I looked at top, I saw: top - 16:14:51 up 6 days, 1:49, 8 users, load average: 24.29, 24.33 17.54 Tasks: 203 total, 7 running, 195 sleeping, 0 stopped, 1 zombie Cpu(s): 0.2%us, 25.6%sy, 0.0%ni, 74.3%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 8056656k total, 5927580k used, 2129076k free, 20320k buffers Swap: 7811064k total, 240216k used, 7570848k free, 5045884k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 21549 root 39 19 0 0 0 Z 100 0.0 15:02.44 [vmware-vmx] <defunct> 2115 root 20 0 0 0 0 S 1 0.0 170:32.08 [vmware-rtc] 2231 root 21 1 1494m 126m 100m S 1 1.6 892:58.05 /usr/lib/vmware/bin/vmware-vmx -# product=2; 2280 jnet 20 0 19320 1164 800 R 0 0.0 30:04.55 top 12236 root 20 0 833m 41m 34m S 0 0.5 88:34.24 /usr/lib/vmware/bin/vmware-vmx -# product=2; 1 root 20 0 23704 1476 920 S 0 0.0 0:00.80 /sbin/init 2 root 20 0 0 0 0 S 0 0.0 0:00.01 [kthreadd] 3 root RT 0 0 0 0 S 0 0.0 0:00.00 [migration/0] 4 root 20 0 0 0 0 S 0 0.0 0:00.84 [ksoftirqd/0] 5 root RT 0 0 0 0 S 0 0.0 0:00.00 [watchdog/0] 6 root RT 0 0 0 0 S 0 0.0 0:00.00 [migration/1] The VMWare process for the virtual machine I was installing into became a zombie. Yet, it was still consuming 100% of the CPU time on one of the cores, and I couldn't reach it or any other virtual machines. (I was logged in to one virtual machine over SSH, another via X11, and a third via VNC. All three connections died). When I ran ps -ef and similar commands, I found that the defunct vmware-vmx process had it's parent PID set to init (1). I also used lsof -p 21549 and found that the defunct process had no open files. Yet it was using 100% of CPU time... I was unable to kill any vmware-vmx processes, including the defunct one, even with kill -9. As a last resort to resolve the situation I tried to reboot the box, however shutdown, halt, reboot, and init 6 all failed to reboot/shutdown, even when given appropriate --force settings. ControlAltDel produced a message about rebooting on the console, but the system would not reboot. I had to hard power-cycle the box to resolve the situation. (See my other question, Should I worry about the integrity of my linux software RAID5 after a crash or kernel panic?) What would cause a scenario like this? What else could I have done to resolve it besides a hard reboot? What can I do to prevent such a situation in the future?

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• Linux software RAID6: rebuild slow

  - by Ole Tange

  I am trying to find the bottleneck in the rebuilding of a software raid6. ## Pause rebuilding when measuring raw I/O performance # echo 1 > /proc/sys/dev/raid/speed_limit_min # echo 1 > /proc/sys/dev/raid/speed_limit_max ## Drop caches so that does not interfere with measuring # sync ; echo 3 | tee /proc/sys/vm/drop_caches >/dev/null # time parallel -j0 "dd if=/dev/{} bs=256k count=4000 | cat >/dev/null" ::: sdbd sdbc sdbf sdbm sdbl sdbk sdbe sdbj sdbh sdbg 4000+0 records in 4000+0 records out 1048576000 bytes (1.0 GB) copied, 7.30336 s, 144 MB/s [... similar for each disk ...] # time parallel -j0 "dd if=/dev/{} skip=15000000 bs=256k count=4000 | cat >/dev/null" ::: sdbd sdbc sdbf sdbm sdbl sdbk sdbe sdbj sdbh sdbg 4000+0 records in 4000+0 records out 1048576000 bytes (1.0 GB) copied, 12.7991 s, 81.9 MB/s [... similar for each disk ...] So we can read sequentially at 140 MB/s in the outer tracks and 82 MB/s in the inner tracks on all the drives simultaneously. Sequential write performance is similar. This would lead me to expect a rebuild speed of 82 MB/s or more. # echo 800000 > /proc/sys/dev/raid/speed_limit_min # echo 800000 > /proc/sys/dev/raid/speed_limit_max # cat /proc/mdstat md2 : active raid6 sdbd[10](S) sdbc[9] sdbf[0] sdbm[8] sdbl[7] sdbk[6] sdbe[11] sdbj[4] sdbi[3](F) sdbh[2] sdbg[1] 27349121408 blocks super 1.2 level 6, 128k chunk, algorithm 2 [9/8] [UUU_UUUUU] [=========>...........] recovery = 47.3% (1849905884/3907017344) finish=855.9min speed=40054K/sec But we only get 40 MB/s. And often this drops to 30 MB/s. # iostat -dkx 1 sdbc 0.00 8023.00 0.00 329.00 0.00 33408.00 203.09 0.70 2.12 1.06 34.80 sdbd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 sdbe 13.00 0.00 8334.00 0.00 33388.00 0.00 8.01 0.65 0.08 0.06 47.20 sdbf 0.00 0.00 8348.00 0.00 33388.00 0.00 8.00 0.58 0.07 0.06 48.00 sdbg 16.00 0.00 8331.00 0.00 33388.00 0.00 8.02 0.71 0.09 0.06 48.80 sdbh 961.00 0.00 8314.00 0.00 37100.00 0.00 8.92 0.93 0.11 0.07 54.80 sdbj 70.00 0.00 8276.00 0.00 33384.00 0.00 8.07 0.78 0.10 0.06 48.40 sdbk 124.00 0.00 8221.00 0.00 33380.00 0.00 8.12 0.88 0.11 0.06 47.20 sdbl 83.00 0.00 8262.00 0.00 33380.00 0.00 8.08 0.96 0.12 0.06 47.60 sdbm 0.00 0.00 8344.00 0.00 33376.00 0.00 8.00 0.56 0.07 0.06 47.60 iostat says the disks are not 100% busy (but only 40-50%). This fits with the hypothesis that the max is around 80 MB/s. Since this is software raid the limiting factor could be CPU. top says: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 38520 root 20 0 0 0 0 R 64 0.0 2947:50 md2_raid6 6117 root 20 0 0 0 0 D 53 0.0 473:25.96 md2_resync So md2_raid6 and md2_resync are clearly busy taking up 64% and 53% of a CPU respectively, but not near 100%. The chunk size (128k) of the RAID was chosen after measuring which chunksize gave the least CPU penalty. If this speed is normal: What is the limiting factor? Can I measure that? If this speed is not normal: How can I find the limiting factor? Can I change that?

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• My computer freezes irregurarly

  - by Manhim

  My computer started to freeze at irregular times for 3 weeks now. What happens My computer freezes, the video stops. (No graphic glitches, it just stops) Sound keeps playing up to some time (Usually 10-30 seconds) then stops playing. Sometimes, randomly, the screen on my G-15 keyboard flickers and I see caracters not at the right places. Usually happens for about 1-2 seconds and a bit before my computer freezes. I have to keep the power button pressed for 4 seconds to shut my computer down. I still hear my hard drives and fans working. Sometimes it works with no problems for a full day, some other times it just keeps freezing each time I restart my computer and I have to leave it for the rest of the day. Sometimes my mouse freezes for a fraction of a second (Like 0.01 to 0.2 seconds) quite randomly, usually before it freezes. No errors spotted by the "Action center" unlike when I had problems with my last video card on this system (Driver errors). My G-15 LCD screen also freezes. What I did so far I have had similar problems in the past and I had changed my hard drive (It was faulty), so I tested my software RAID-0 array and it was faulty so I changed it. (I reinstalled Windows 7 with this part). I also tested with unplugging my secondary hard drive. My CPU was running at about 100 degree Celsius, I removed the dust between the fans and the heatsink and it's now between 50-60. I ran a CPU stress-test and it didn't freeze during the tests (using Prime95 on all cores) Ran a memory test (using memtest86+) for a single pass and there were no errors. Ran a GPU stress test with ati-tools and furmark and it didn't freeze during the tests. (No artefacts either) I had troubles with my graphic card when I got it, but I think that it got fixed with a driver update. I checked the voltages in my BIOS setup and they all seemed ok (±0.2 I think). I have ran on the computer without problems with Fedora 15 on an external hard drive (Appart that it couldn't load Gnome 3 and was reverting to Gnome 2, didn't want to install drivers since I use it on multiple computers) I used it to backup my files from the raid array to my 1TB hard drive for the reinstallation of Windows. (So the crashes only happenned on Windows) [The external hard drive is plugged directly on a SATA port] I contacted EVGA (My graphic card vendor) and pointed them on this question, I'm looking for an answer. Ran sensors on Fedora 15 and got this output: http://pastebin.com/0BHJnAvu When it happens When I play video games (Mostly) When I play flash games (Second most) When I'm looking at my desktop background (It rarely happens when I have a window open, but it does, sometimes) Specs Windows Seven x64 Home Premium Motherboard: M2N-SLI Deluxe CPU: AMD Phenom 9950 x2 @ 2.6GHz Memory: Kingston 4x2GB Dual Channel (Pretty basic memory sticks) Hard drives: Was 2x250GB (Western digital caviar) in raid-0 + 1TB (WD caviar black), I replaced the raid array with a 750GB (WD caviar black) [Yes I removed the array from the raid configurations] 750W Power supply No overcloking. Ever. There have been some power-downs like 4-5 weeks ago, but the problem didn't start immediately after. (I wasn't home, so my computer got shut-down) My current to-try list Change the thermal paste on my CPU. Change my graphic card with a temporary one and stress the computer. Change my power supply. In this situation, how can I successfully pin-point the current hardware problem? (If it's a hardware problem) Because I don't really have the budget to just forget and replace everything. I also don't really have hardware to test-replace current hardware.

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• Where is my VMware-ws FreeNAS CIFS(ZFS) bottle-neck?

  - by maka

  Background: I'm building a quiet HTPC + NAS that is also supposed to be used for general computer usage. I'm so far generally happy with things, it was just that I was expecting a little better IO performance. I have no clue if my expectations are unreal. The NAS is there as a general purpose file storage and as a media server for XBMC and other devices. ZFS is a requirement. Question: Where is my bottle-neck, and is there anything I can do config wise, to improve my performance? I'm thinking VM-disk settings could be something but I really have no idea where to go since I'm neither experienced with FreeNAS nor VMware-WS. Tests: When I'm on the host OS and copy files (from the SSD) to the CIFS share, I get around 30 Mbytes/sec read and write. When I'm on my laptop laptop, wired to the network, I get about the same specs. The test I've done are with a 16 GB ISO, and with about 200 MB of RARs and I've tried avoiding the RAM-cache by reading different files than the ones I'm writing ( 10 GB). It feels like having less CPU cores is a lot more efficient, since the resource manager in Windows reports less CPU-usage. With 4 cores in VMware, CPU usage was 50-80%, with 1 core it was 25-60%. EDIT: HD ActiveTime was quite high on SSD so I moved the page file, disabled hibernate and enabled Win DiskCache both on SSD and RAID. This resulted in no real performance difference for one file, but if i transferred 2 files the total speed went up to 50 Mbytes/s vs ~40. The ActiveTime avg also went down a lot (to ~20%) but has now higher bursts. DiskIO is on ~ 30-35 Mbytes/s avgs, with ~100Mb bursts. Network is on 200-250Mbits/s with ~45 active TCP connections. Hardware Asus F2A85-M Pro A10-5700 16GB DDR3 1600 OCZ Vertex 2 128GB SSD 2x Generic 1tb 7200 RPM drives as RAID0 (in win7) Intel Gigabit Desktop CT Software Host OS: Win7 (SSD) VMware Worksation 9 (SSD) FreeNAS 8.3 VM (20GB VDisk on SSD) CPU: I've tried 1, 2 and 4 cores. Virtualisation engine, Preferred mode: Automatic 10,24Gb ram 50Gb SCSI VDisk on the RAID0, VDisk is formatted as ZFS and exposed through CIFS through FreeNAS. NIC Bridge, Replicate physical network state Below are two typical process print-outs while I'm transfering one file to the CIFS share. last pid: 2707; load averages: 0.60, 0.43, 0.24 up 0+00:07:05 00:34:26 32 processes: 2 running, 30 sleeping Mem: 101M Active, 53M Inact, 1620M Wired, 2188K Cache, 149M Buf, 8117M Free Swap: 4096M Total, 4096M Free PID USERNAME THR PRI NICE SIZE RES STATE TIME WCPU COMMAND 2640 root 1 102 0 50164K 10364K RUN 0:25 25.98% smbd 1897 root 6 44 0 168M 74808K uwait 0:02 0.00% python last pid: 2746; load averages: 0.93, 0.60, 0.33 up 0+00:08:53 00:36:14 33 processes: 2 running, 31 sleeping Mem: 101M Active, 53M Inact, 4722M Wired, 2188K Cache, 152M Buf, 5015M Free Swap: 4096M Total, 4096M Free PID USERNAME THR PRI NICE SIZE RES STATE TIME WCPU COMMAND 2640 root 1 76 0 50164K 10364K RUN 0:52 16.99% smbd 1897 root 6 44 0 168M 74816K uwait 0:02 0.00% python I'm sorry if my question isn't phrased right, I'm really bad at these kind of things, and it is the first time I post here at SU. I also appreciate any other suggestions to something, I could have missed.

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