Forum > Linux
SETI MB CUDA for Linux
Raistmer:
The problem with Linux it cosumes 100% of CPU clock, not 2,5%....
Jason G:
Sure, that's an implementation issue they'll need to work out, and maybe something about their cuda drivers & SDK etc on that platform (We know how well beta 2.1 SDK is refined on Windows after all.)
If fixable, I can reasonably expect that their apps would still report 1.5->2x the CPU time as the windows ones, since the Windows one has that hidden component.
[ Edit: Without knowing about how Linux schedules its processes, It's probably implemented with spin-wait polling loops instead of interrupts & DPCs, so reports 100% CPU, even though only some fraction of that is used for useful work. in a spin-wait, it shouldn't be blocking other threads or resources anyway, so it shouldn't really prevent any other app running etc... even though it says 100%.
It would be interesting to know the behaviour on Linux when a CPU wants to use that core, if the Cuda app yields most of the percentage or not. ]
Raistmer:
About hidden component - interesting to measure it more accurately.
I understood that I could miss it in my tests (I measured only single core, other was used by BOINC) Will try to run 4 CPU apps + 1 GPU app all in standalone under appTimes control. This way all elapsed times will be accounted - no hidden component at all.
Jason G:
Yeah difficult to nail down, as it won't show in wall or cpu time for that app. It will be small, but large in proportion to reported CPU time & consume about 50% on top of whatever reported cpu time is. Only way I've been able to see this figure is in process explorer.
next question is does it matter? Well no, because it is really hidden and doesn't add to wall time, but it does consume some small portion of overall machine resources available to other apps.
Raistmer:
--- Quote from: Jason G on 13 Mar 2009, 12:45:28 pm ---next question is does it matter? Well no, because it is really hidden and doesn't add to wall time, but it does consume some small portion of overall machine resources available to other apps.
--- End quote ---
And that portion should be known to do decisions about best host configs and performance tuning.
Overall host performance - that's really matter, not performance of just single app .
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