Performance: 4 CPUs -vs- 4+1 (9800gtx+)

Message boards : Graphics cards (GPUs) : Performance: 4 CPUs -vs- 4+1 (9800gtx+)

Author	Message
JStateson Send message Joined: 31 Oct 08 Posts: 186 Credit: 3,383,872,624 RAC: 1,320,643 Level Scientific publications	Message 5181 - Posted: 3 Jan 2009 \| 2:51:49 UTC
	Ran a quick test that indicated I am better off dedicating a full CPU to the GPU. This is how I figured it. I observed there were 15,000 seconds of CPU time available in 4+1 mode. That corresponds to an average of 800 GPUGRID credits (the 15k secs). I could not find any project that would give me 800 credits in 15,000 seconds.
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MarkJ Volunteer moderator Volunteer tester Send message Joined: 24 Dec 08 Posts: 738 Credit: 200,909,904 RAC: 0 Level Scientific publications	Message 5189 - Posted: 3 Jan 2009 \| 11:39:37 UTC - in response to Message 5181. Last modified: 3 Jan 2009 \| 11:43:47 UTC
	Ran a quick test that indicated I am better off dedicating a full CPU to the GPU. This is how I figured it. I observed there were 15,000 seconds of CPU time available in 4+1 mode. That corresponds to an average of 800 GPUGRID credits (the 15k secs). I could not find any project that would give me 800 credits in 15,000 seconds. I can't see why you'd need to dedicate a core to it. At the moment i'm running 4+1 using BOINC 6.5.0 without needing a cc_config.xml file. It runs the feeder task at "below normal" priority. I find that if I increase its priority to "normal" the run times come down (about 10 hours on a 9800GT). Obviously there is an impact on the cpu tasks running, but only a minimal effect, so you still get other work units processed on the cpu without having to dedicate a core. When the 6.56 app gets corrected the impact should be even less.
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ExtraTerrestrial Apes Volunteer moderator Volunteer tester Send message Joined: 17 Aug 08 Posts: 2705 Credit: 1,311,122,549 RAC: 0 Level Scientific publications	Message 5215 - Posted: 3 Jan 2009 \| 19:26:52 UTC
	Interesting, in your case the GPU really suffers in 4+1 compared to 3+1 (labeled 4 in your image). In the case of such a huge difference you're really better off with 3+1. In my case the 9800GTX+ goes from 49 ms/step to 55 - 60 ms/step when switching from 3+1 to 4+1 and even with this smaller difference I figured running 3+1 would be more effective. And the faster the card the more pronounced the difference becomes. MrS ____________ Scanning for our furry friends since Jan 2002
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Message boards : Graphics cards (GPUs) : Performance: 4 CPUs -vs- 4+1 (9800gtx+)

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