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M5WJF

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Message 69130 - Posted: 27 Sep 2019, 19:54:29 UTC

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.
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swiftmallard
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Message 69132 - Posted: 27 Sep 2019, 22:04:01 UTC - in response to Message 69130.  

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.
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mmonnin

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Message 69142 - Posted: 30 Sep 2019, 13:45:25 UTC

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.
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rbpeake

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Message 69237 - Posted: 8 Nov 2019, 13:51:54 UTC

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.
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Profilemikey
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Message 69240 - Posted: 9 Nov 2019, 12:10:58 UTC - in response to Message 69237.  

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!


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.
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rbpeake

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Message 69246 - Posted: 11 Nov 2019, 16:18:43 UTC - in response to Message 69240.  
Last modified: 11 Nov 2019, 16:19:37 UTC

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!


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.


Would you happen to know the entire app_config.xml statement/expression? I am not very familiar with these files.

Thanks!
Regards,
Bob P.
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ProfileJoseph Stateson
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Message 69248 - Posted: 11 Nov 2019, 16:54:03 UTC - in response to Message 69246.  


Would you happen to know the entire app_config.xml statement/expression? I am not very familiar with these files.

Thanks!


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.
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ProfileKeith Myers
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Message 69249 - Posted: 12 Nov 2019, 7:09:28 UTC
Last modified: 12 Nov 2019, 7:39:22 UTC

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.
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rbpeake

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Message 69250 - Posted: 12 Nov 2019, 12:25:14 UTC - in response to Message 69249.  

Thanks!
Regards,
Bob P.
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