Forum > Linux
SETI MB CUDA for Linux
Jason G:
--- Quote from: Raistmer on 13 Mar 2009, 11:21:22 am ---No, you missed that if CPU is busy - it's busy.
But if CPU free - it can be used somewhere else.
It seems in Linux CPU is busy all time CUDA app runs (I can do conclusions only by read posts of course, didn't run it on own host).
--- End quote ---
You missed that If I'm spending time in a kernel driver, I can attribute it to the program or not. Windows doesn't.
Raistmer:
Again, I _measured_ elapsed times in config all cores busy with CPU app for CUDA app and measured elapsed time for CPU app when CUDA app running and other cores busy too.
So, NO noticeable kernel time increase here, all fair.
Linux does something wrong here it seems...
Jason G:
Watch deferred procedure Calls process (DPCs) %CPUusage in process explorer, with & without Cuda app running.
Raistmer:
--- Quote from: Jason G on 13 Mar 2009, 11:45:33 am ---Watch deferred procedure Calls process (DPCs) %CPUusage in process explorer, with & without Cuda app running.
--- End quote ---
For what? Elapsed == WALL CLOCK.
Jason G:
--- Quote from: Raistmer on 13 Mar 2009, 11:47:00 am ---
--- Quote from: Jason G on 13 Mar 2009, 11:45:33 am ---Watch deferred procedure Calls process (DPCs) %CPUusage in process explorer, with & without Cuda app running.
--- End quote ---
For what? Elapsed == WALL CLOCK.
--- End quote ---
That's why I said, Use only wall clock for app comparison.
Deferred procedure calls are executing on another core in another process space, so counts as no extra wall clock or CPU time for that Cuda Process... even though it was made by it.(and consumes resources)
DPC CPU usage with no Cuda App running ~0.77%
DPC CPU usage with Cuda Running ~2.5%
(~3 x)
Which is a full ~50% of the Cuda app shunted off to another kernel process, which will Not effect ELAPSED WALL-CLOCK, because it runs on another core, or register on app CPU_TIME either.
Linux has no windows deferred procedure calls AFAIK (could be wrong) , so cannot shunt of the CPU time to aniother process / core, so cops the cputime allocation locally.
(i.e. Windows is giving extra hidden CPU time to cuda app, there is no magic. )
http://en.wikipedia.org/wiki/Deferred_Procedure_Call
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version