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Yakk

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Message 40911 - Posted: 14 Jul 2010, 5:31:29 UTC

My 5870 has been burning through WU's in +/- 80-85 seconds per WU. However between WU's I can see a drop in GPU activity, it is very short, but it is a drop.

This drop is it lost time as the WU changes? Would longer WU's increase effeciancy? Or it is code being unloaded & reloaded into the graphics card? I'm only asking this questions because the WU's fly by so quickly this drop happens very often.

Y.
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TJ

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Message 40994 - Posted: 19 Jul 2010, 21:23:06 UTC

This drop is it lost time as the WU changes? Would longer WU's increase effeciancy? Or it is code being unloaded & reloaded into the graphics card? I'm only asking this questions because the WU's fly by so quickly this drop happens very often.


Hi Yakk,

This normal. When a WU is finished the GPU has less to do and its activity degreases. When a few secs later a new WU starts it increases again. And so on.
You can see the same when looking at its temperature curve.
Greetings from,
TJ
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Zydor
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Message 40996 - Posted: 19 Jul 2010, 21:57:49 UTC - in response to Message 40911.  

There is an unload / load time of 2 secs a go, as the old one is pulled out by the cpu, and the new one is loaded. On some slower cards that can be about 3 seconds, nothing you can do, its a pure load/unload process
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Vid Vidmar*
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Message 41003 - Posted: 20 Jul 2010, 7:52:17 UTC - in response to Message 40996.  

That's why some of us use app_info.xml files to get 2 WUs running concurrently on single GPU. If their start time is offset by more than 2s then there is no dip in GPU activity.
BR,
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Emanuel

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Message 41006 - Posted: 20 Jul 2010, 11:35:43 UTC

So yes, having longer WUs would technically increase GPU utilization slightly. But there's no simple way to artificially increase WU size - the WUs would actually have to do more calculations, or do the same calculations at a higher precision. That has already been done several times, but at this point I think you'd have to develop a more complex model to benefit from increased precision or wider strips of the sky.
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