GPU usage oscillation


log in

Advanced search

Message boards : Number crunching : GPU usage oscillation

Author Message
Sean Arrowsmith
Send message
Joined: 17 Feb 01
Posts: 26
Credit: 4,765,551
RAC: 515
United Kingdom
Message 1404206 - Posted: 17 Aug 2013, 7:16:53 UTC
Last modified: 17 Aug 2013, 7:18:20 UTC

Hello,

I have been try to work out what is happening on one of my PC's
http://setiathome.berkeley.edu/show_host_detail.php?hostid=7068185

The system is AMD X645 with 8Gb memory and GTX460 (1Gb)
I have just wiped the HD and reinstalled Win7, followed by Nvidia drivers 320.49

I put BOINC V7.0.64 (64bit) on and reattached to BAM which downloaded downloaded SETI and Engima. I then installed Lunatics 0.41 64bit installer.

Upon running MSI Afterburner I can see the GPU usage going up and down. ie the usage oscillation at 99% for 7 seconds then drops to 30% for one seconds and then back up to 99% and so on it goes up and down.

None of my other Nvidia PC's do this, is there a reason or a setting for this oscillation

The GTX460 only is set up to crunch SETI MB Cuda WU

Thank you
____________

Profile Mike
Volunteer tester
Avatar
Send message
Joined: 17 Feb 01
Posts: 22468
Credit: 29,504,487
RAC: 25,495
Germany
Message 1404210 - Posted: 17 Aug 2013, 7:28:28 UTC

You probably need to free a CPU core on that host to feed the GPU properly.

____________

Richard Haselgrove
Volunteer tester
Send message
Joined: 4 Jul 99
Posts: 8278
Credit: 45,033,309
RAC: 13,622
United Kingdom
Message 1404249 - Posted: 17 Aug 2013, 9:30:44 UTC - in response to Message 1404210.
Last modified: 17 Aug 2013, 9:44:46 UTC

You probably need to free a CPU core on that host to feed the GPU properly.

Maybe he already tried to free a core, but by mistake used the wrong %age box?

If you set the "Use at most ... %CPU time" control, it will run as described - all CPUs for 7 seconds on, 1 second off at 87.5%

Instead, set that value to 100%, and use the alternative "use at most ... % of the processors" - at 87.5%, that will keep 3 CPUs continuously occupied (on his quad core), and leave one free.

Not that it should be necessary, since he's running Cuda, not OpenCL.

Edit - there was a range of BOINC clients - v7.0.45 thru v7.2.0 - where David (inadvisedly IMHO) made CPU time throttling apply to GPU apps too. Unfortunately, this includes the currently-recommended v7.0.64 which Sean is using.

Profile jason_gee
Volunteer developer
Volunteer tester
Avatar
Send message
Joined: 24 Nov 06
Posts: 4823
Credit: 71,661,475
RAC: 9,884
Australia
Message 1404270 - Posted: 17 Aug 2013, 11:24:01 UTC - in response to Message 1404206.
Last modified: 17 Aug 2013, 11:33:10 UTC

...The GTX460 only is set up to crunch SETI MB Cuda WU


Under those circumstances, I'd recommend lifting the application defaults in mbcuda.cfg, for a 460 more or less dedicated running Cuda MB, around:

[mbcuda]
processpriority = abovenormal
pfblockspersm = 4
pfperiodsperlaunch = 200

Also, perhaps check there aren't any crazy unnecessary motherboard utilities, or other background processes you don't want/need, running. Not that erratic usage is a problem, if expected due to using the PC, but annoying if youthink the system is clean & there is other stuff stealing the Bus (Been there ;) ).
____________
"It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change."
Charles Darwin

Message boards : Number crunching : GPU usage oscillation

Copyright © 2014 University of California