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Posts by Kristoffer

1) Message boards : News : New Runs for MilkyWay@home Nbody Simulations (07/29/2020) (Message 70114)
Posted 8 Sep 2020 by Kristoffer
Post:
Actually the correct method of defining mt app is provided in the BOINC configuration document.
https://boinc.berkeley.edu/wiki/Client_configuration#Application_configuration

They provide an example.

[<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>]

So if you want to run 3 tasks with 8 cores each your app_config should look something like this.

<app_config>
<app>
<name>milkyway_nbody</name>
<max_concurrent>3</max_concurrent>
</app>
<app_version>
<app_name>milkyway_nbody</app_name>
<plan_class>mt</plan_class>
<cmdline>--nthreads 8</cmdline>
</app_version>
</app_config>

The --nthreads parameter is the actual controller of how many cpu threads are utilized per each task.


Thanks a lot! Looks like it solved my issue as well!

By default the milkyway_nbody process was single instance, distributed over all my threads, taking several days to finish. The CPU utilisation was almost nada, ie idling around 1% overall.

The latter variant of the xml-file seems to work well in my case. After Jim's advice, I restricted it to only a single thread per process, and increased the maximum number of parallel processes accordingly.

After saving the app_config.xml in the projects app-data folder, I suspended the milkyway project, waited a minute or so, then resumed. The ongoing process then resumed without any visible change, and finished in about 25 mins what it had spent several days doing already. Full CPU utilisation on all cores/threads.

So, great! However, weird that this isn't solved on the server side as others have pointed out. It's a real time waste for the other projects when the milkyway instances are run so inefficiently..

For reference, here's my C:\ProgramData\BOINC\projects\milkyway.cs.rpi.edu_milkyway\app_config.xml
<app_config>
	<app>
		<name>milkyway_nbody</name>
		<max_concurrent>8</max_concurrent>
	</app>
	<app_version>
		<app_name>milkyway_nbody</app_name>
		<plan_class>mt</plan_class>
		<cmdline>--nthreads 1</cmdline>
	</app_version>
</app_config>




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