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yurtesen
Miniboss

Re: GPU tasks performance issue when screen goes into standby mode

I am getting exactly same behavior even when compiz is 100% (I had first iteration little slower sometimes in my previous tests also) (this is on 5870, 850mhz GPU /1200mhz GDDR5)

# ./a.out

steps per 10 secs : 4638

steps per 10 secs : 5061

steps per 10 secs : 5058

steps per 10 secs : 5062

steps per 10 secs : 5064

steps per 10 secs : 5065

^C

top - 01:12:20 up  4:48,  4 users,  load average: 1.37, 1.37, 1.44

Tasks: 199 total,   2 running, 196 sleeping,   0 stopped,   1 zombie

Cpu(s):  2.4%us, 11.9%sy,  0.0%ni, 85.8%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st

Mem:  16435264k total,  1392672k used, 15042592k free,    35116k buffers

Swap: 16775164k total,        0k used, 16775164k free,   431780k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND

4066 supremum  20   0 1284m  90m  44m R  100  0.6 147:32.48 compiz

7698 root      20   0  174m  53m  22m S   10  0.3   0:01.83 a.out

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c0nfig
Journeyman III

Re: GPU tasks performance issue when screen goes into standby mode

Hi,

Thanks for your test.

Hmm, so maybe it depends on the card,

I'll install a clean Ubuntu to test this program again.

Also, the fact that 5870 outperform my 7970 is suspicious.

Just to be sure, please tell me if you are you not using  the latest version of the APP SDK and the graphics drivers.

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yurtesen
Miniboss

Re: GPU tasks performance issue when screen goes into standby mode

I have the box with 7970 up and running, I will soon return back with some numbers. I am using SDK 2.7, and 12.6 drivers (I mentioned it earlier). Actually I just installed ubuntu 12.04 from scratch to this box.

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yurtesen
Miniboss

Re: GPU tasks performance issue when screen goes into standby mode

Hmm, right something is strange here... GPU load shows 0%

Adapter 0 - AMD Radeon HD 7900 Series

                            Core (MHz)    Memory (MHz)

           Current Clocks :    300           150

             Current Peak :    1010           1375

  Configurable Peak Range : [300-1125]     [150-1575]

                 GPU load :    0%

and the performance is terrible...

$ ./a.out

steps per 10 secs : 1448

steps per 10 secs : 1465

steps per 10 secs : 1468

steps per 10 secs : 1465

Anyway, there is a problem in your loop also. You are not waiting for kernel execution to finish before running the enqueueread? I get 50% better performance if I put a clfinish between enqueue kernel and enqueue read statements. But that is not very efficient... (on 7970, it now uses 50% of the card with clfinish, you should find a better solution ...)

on the other hand, if I put clFinish on 5870, there is no difference in execution....

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c0nfig
Journeyman III

Re: GPU tasks performance issue when screen goes into standby mode

Clfinish is necessary ? The command queue keeps the order of the clenqueue commands and the clEnqueueReadBuffer is blocking. Am I missing something here ?

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yurtesen
Miniboss

Re: GPU tasks performance issue when screen goes into standby mode

Yes, when you enqueue a kernel, the host program will continue and run the readbuffer command (which will try to read data from where your kernel is working on in a blocked fashion). Because the enqueue kernel command is not blocking. You should use events to keep track of kernel execution and try not to read/write to memory areas which are used by the kernel while it is executing (obviously). I think I am right, but double check from the manual

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