Message boards : Number crunching : Limit of 64 Logical Processors / Cores Per Host?
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SKAFFEN

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Message 4377 - Posted: 26 Jun 2020, 18:55:04 UTC

I run U@H along with Asteroids, Milkyway and Einstein on a machine with 2x 28 core CPU's, 56 cores total, with hyperthreading on to give 112 logical processors. Machine ID: 564374, Ranked Number 10 by RAC at the moment.

This is on Windows 10 for Workstations, I already have found that Windows 10 Pro does not handle NUMA nodes for systems with more than 64 logical processors correctly.

This machine does not seem to work well with Universe@home, which will only let 64 logical processors operate, or so it seems to me.

Universe@Home also seems to stop the other BOINC tasks using the remaining logical processors while running, so processor utilization is never more than 70% with even a single U@H task running alongside other BOINC projects, but immediately ramps up to 100% on all logical processors when I suspend U@H, and let other BOINC projects take over.

This does not happen on my other machine with 2x 10 core CPU's, with hyperthreading on to give 40 logical processors. That one runs completely happily at 100% whatever is running under BOINC.

It seems like I can't change anything in my setup to improve this behavior, any suggestions?

Cheers
SKAFFEN
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Profile Keith Myers
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Message 4378 - Posted: 26 Jun 2020, 19:34:35 UTC

The default project ncpus configuration is 64. Seems that is what Universe is using.

https://boinc.berkeley.edu/forum_thread.php?id=12877#90743

Try setting <ncpus>112</ncpus> in the Options section of the client cc_config.xml file. Stop and restart the client and see if that allows all the cpu threads to be used.

I still think you are going to be limited on the project side configuration though.

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Freewill

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Message 4439 - Posted: 27 Aug 2020, 18:01:09 UTC

Hi SKAFFEN,
Did Keith's suggestion work for you or was U@H still the limiting issue?

Thanks!
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Message 4440 - Posted: 27 Aug 2020, 19:07:00 UTC - in response to Message 4439.  

Hi SKAFFEN,
Did Keith's suggestion work for you or was U@H still the limiting issue?

Thanks!

I'm curious myself. You haven't run into the issue yet because you only have 56 threads on your dual socket Xeon host, correct?

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Message 4441 - Posted: 27 Aug 2020, 19:09:47 UTC - in response to Message 4440.  

Not an issue on my 56 thread box, but I am thinking ahead. ;)
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Profile Krzysztof Piszczek - wspieram ...
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Message 4442 - Posted: 27 Aug 2020, 20:02:44 UTC - in response to Message 4377.  


This is on Windows 10 for Workstations


Can you try any Linux distribution (live one) just to try if the same behaviour happens?
I haven't any machine to test this :(
Krzysztof 'krzyszp' Piszczek

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Profile Keith Myers
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Message 4443 - Posted: 27 Aug 2020, 20:23:44 UTC

Looks like the volunteer got discouraged with the problem of too many threads and left the project. Hasn't contacted the project since their post.

So doesn't look like we will have any answer on whether Linux is any better than Windows for Workstations at Universe@home.

I wouldn't expect any issues since Linux has understood NUMA for a long, long while.

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Message 4462 - Posted: 4 Sep 2020, 5:12:31 UTC
Last modified: 4 Sep 2020, 5:16:43 UTC

Well a team member just put a 96 thread AMD Epyc host online and working for Universe. No issues at all running 92 threads simultaneously.

https://universeathome.pl/universe/show_host_detail.php?hostid=571864

So that answers the question of this thread. No limit of 64 logical processors here.

At least for Linux.

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Message boards : Number crunching : Limit of 64 Logical Processors / Cores Per Host?




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