Welcome to MilkyWay@home

How many CPUs?

Message boards : Number crunching : How many CPUs?
Message board moderation

To post messages, you must log in.

AuthorMessage
M5WJF

Send message
Joined: 6 Sep 19
Posts: 1
Credit: 3,992,152
RAC: 0
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.
ID: 69130 · Rating: 0 · rate: Rate + / Rate - Report as offensive     Reply Quote
swiftmallard
Avatar

Send message
Joined: 18 Jul 09
Posts: 300
Credit: 303,565,482
RAC: 0
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.
ID: 69132 · Rating: 0 · rate: Rate + / Rate - Report as offensive     Reply Quote
mmonnin

Send message
Joined: 2 Oct 16
Posts: 167
Credit: 1,008,060,675
RAC: 11,420
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.
ID: 69142 · Rating: 0 · rate: Rate + / Rate - Report as offensive     Reply Quote
rbpeake

Send message
Joined: 29 Aug 07
Posts: 21
Credit: 1,050,702
RAC: 0
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.
ID: 69237 · Rating: 0 · rate: Rate + / Rate - Report as offensive     Reply Quote
Profile mikey
Avatar

Send message
Joined: 8 May 09
Posts: 3339
Credit: 524,010,781
RAC: 0
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.
ID: 69240 · Rating: 0 · rate: Rate + / Rate - Report as offensive     Reply Quote
rbpeake

Send message
Joined: 29 Aug 07
Posts: 21
Credit: 1,050,702
RAC: 0
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.
ID: 69246 · Rating: 0 · rate: Rate + / Rate - Report as offensive     Reply Quote
Profile Joseph Stateson
Avatar

Send message
Joined: 18 Nov 08
Posts: 291
Credit: 2,461,693,501
RAC: 0
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.
ID: 69248 · Rating: 0 · rate: Rate + / Rate - Report as offensive     Reply Quote
Profile Keith Myers
Avatar

Send message
Joined: 24 Jan 11
Posts: 714
Credit: 554,823,206
RAC: 35,528
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.
ID: 69249 · Rating: 0 · rate: Rate + / Rate - Report as offensive     Reply Quote
rbpeake

Send message
Joined: 29 Aug 07
Posts: 21
Credit: 1,050,702
RAC: 0
Message 69250 - Posted: 12 Nov 2019, 12:25:14 UTC - in response to Message 69249.  

Thanks!
Regards,
Bob P.
ID: 69250 · Rating: 0 · rate: Rate + / Rate - Report as offensive     Reply Quote

Message boards : Number crunching : How many CPUs?

©2024 Astroinformatics Group