Message boards :
Number crunching :
How many CPUs?
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Author | Message |
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Send message Joined: 6 Sep 19 Posts: 1 Credit: 3,992,152 RAC: 0 |
Ok, I've run SETI@home exclusively since I joined the project in 1999, but earlier this month decided to add this project, but I now have a query. Just how many CPUs does BOINC / SETI@home / MilkyWay@home think my computer has? According to BOINC 0.0497 of a CPU is being using along with the GPU for a v8 8.00 (cuda42) for SETI 1 CPU is running a MilkyWay N-Body Sim v1.76 1 CPU is running a MilkyWay N-Body Sim v1.76 6 CPUs is running a MilkyWay N-Body Sim v1.76 (mt) All very well, but the machine is a Phenom X6 1100T, so there's only 6 cores, so how is it possible to run 8.0497 cores on this machine, when at least 2 don't exist, and the other is a bit of sharing? Just doesn't compute. |
Send message Joined: 18 Jul 09 Posts: 300 Credit: 303,565,482 RAC: 0 |
I noticed the same thing on my six core machine when they switched to multi-threaded WUs. Simply set MW to No New Tasks, then suspend all the multi-threaded units and the old ones will clear out. While you are on NNT, reduce your cache to only a few hours worth of work or you will have scheduling problems when you start back up. |
Send message Joined: 2 Oct 16 Posts: 167 Credit: 1,008,060,675 RAC: 11,420 |
The BOINC Client manages this, not a project. mt apps will sometimes use 1 thread during the initial setup phase prior to the science app starting to do work then BOINC to stop other tasks once the science app starts to use more CPU. The exception I have seen are when there are some tasks close to deadline and in high priority mode. The client needs a full CPU thread to reserve a thread so 0.0497 of a CPU does not count towards your 6 available threads. |
Send message Joined: 29 Aug 07 Posts: 21 Credit: 1,050,702 RAC: 0 |
Is there an app_config.xml configuration to limit the number of cores the multi core CPU application uses? I tried adjusting the Use Only x% of the CPU's, but that does not work. Thanks! Regards, Bob P. |
Send message Joined: 8 May 09 Posts: 3339 Credit: 524,010,781 RAC: 0 |
Is there an app_config.xml configuration to limit the number of cores the multi core CPU application uses? I tried adjusting the Use Only x% of the CPU's, but that does not work. Yes this line does that: <avg_ncpus>4</avg_ncpus> In this case it's limiting the program to only use 4 cpu cores per workunit. |
Send message Joined: 29 Aug 07 Posts: 21 Credit: 1,050,702 RAC: 0 |
Is there an app_config.xml configuration to limit the number of cores the multi core CPU application uses? I tried adjusting the Use Only x% of the CPU's, but that does not work. Would you happen to know the entire app_config.xml statement/expression? I am not very familiar with these files. Thanks! Regards, Bob P. |
Send message Joined: 18 Nov 08 Posts: 291 Credit: 2,461,693,501 RAC: 0 |
At one time the eVga forum had a thread going about app_config files for various projects. https://forums.evga.com/BOINC-app_configxml-file-settings-for-GPU-Projects-m2213432.aspx I learned a few things there but that thread has not been updated for 2 years. You can google for "boinc app_config.xml" and look for various projects I had the idea once of helping put together a wiki for all the various app_config files for all projects but it would required help from the project principals to get, for example, a list of command line arguments to the project's app. I am not sure if some of the moderators even know what options the apps have. |
Send message Joined: 24 Jan 11 Posts: 714 Credit: 554,823,206 RAC: 35,528 |
The documentation for app_config.xml is here: https://boinc.berkeley.edu/wiki/Client_configuration#Application_configuration For mt apps the example you are interested in is here: <app_config> ... [<app_version> <app_name>Application_Name</app_name> [<plan_class>mt</plan_class>] [<avg_ncpus>x</avg_ncpus>] [<ngpus>x</ngpus>] [<cmdline>--nthreads 7</cmdline>] </app_version>] ... [<project_max_concurrent>N</project_max_concurrent>] [<report_results_immediately/>] </app_config> You limit the number of threads that a mt app uses with the [<cmdline>--nthreads 7</cmdline>] statement. To limit to using only 4 threads the 7 becomes 4 in the example. |
Send message Joined: 29 Aug 07 Posts: 21 Credit: 1,050,702 RAC: 0 |
Thanks! Regards, Bob P. |
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