When should you not use a GPU for processing?

Questions and Answers : GPU applications : When should you not use a GPU for processing?
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Profile Tom M
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Message 1948786 - Posted: 10 Aug 2018, 12:18:37 UTC
Last modified: 10 Aug 2018, 12:21:55 UTC

So far I have found evidence for two situations where you should not use a specific GPU for Seti processing.

1) For older Intel (internal) Gpu's like the HD 4000 and HD 620. When you do Seti processing on these gpu's you slow the cpu-based Seti processing down. Now you might apparently get slightly faster processing on the Intel gpu than you get on your cpu's but the whole system slows down so your RAC seems to decrease. My testing with an HD 4000 appears to support this claim.

2) AMD's "All in One" series that integrates the cpu and Radeon gpu's on the motherboard. I have owned a A10-6700 (full sized tower) and now own a A4-5000 (small laptop). Both of them appear to do the following. If you run a gpu task at 100% the cpu's slow down to roughly 20% of the processing speed of the system.

As far as I can tell, the only way to get decent production from the cpus is to stop running the gpu tasks. I had the A10-6700 for over a year. I ran it with both Win8.1 and Win7. The other issue was a tendency for the Video card to crash. When the video card restarted, the Seti gpu processing didn't. You had to restart it manually. So running cpu-based tasks appears to be your best choice.
HTH,
Tom
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Message 1949017 - Posted: 11 Aug 2018, 16:23:03 UTC - in response to Message 1948786.  

I have a A10-6700 CPU with Windows 10 and GPU GTX 1050 Ti. It runs SETI@home both CPU and GPU tasks,and sometimes it crashes all by itself. But the GPU tasks do not crash and go on after a reboot,with no errors. But I see the CPU tasks running somehow slower then when no GPU task is active. RAM is 22 GB, so it should be sufficient for all tasks.
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Message 1949150 - Posted: 12 Aug 2018, 9:26:50 UTC

hi, Raismer even notice this fact here http://lunatics.kwsn.info/index.php/topic,1735.0.html
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Message 1949218 - Posted: 12 Aug 2018, 18:06:19 UTC

I was also pointed to a detailed analysis an A10-5700 that appears to offer a way to mostly run the GPU at full speed and 3 out of 4 cpu's at full speed.

Go into your local settings in BOINC and set the available cpus to 75%. This allows most of the cpus to run much faster than my original experience as well as letting the GPU process at full tilt.

I have been running my A4-5000 this way for the last day or so, and it appears to be working.

Clearly if your A10/A4 etc is running at near 100% for both the cpu and the GPU then my ideas are wrong for your system, at least.

If your cpu "sags" to some really low number while the gpu is processing at full speed then try disabling 1 core as described above and see if the rest of the cpu cores speed up to "near" 100%.

I live and occasionally I learn.

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Message 1949220 - Posted: 12 Aug 2018, 18:14:19 UTC - in response to Message 1949017.  

I have a A10-6700 CPU with Windows 10 and GPU GTX 1050 Ti. It runs SETI@home both CPU and GPU tasks,and sometimes it crashes all by itself. But the GPU tasks do not crash and go on after a reboot,with no errors. But I see the CPU tasks running somehow slower then when no GPU task is active. RAM is 22 GB, so it should be sufficient for all tasks.
Tullio


Since you have an discrete video card is the system also running the internal Radeon card or not? My experience only applies to someone who is trying to do Seti processing without adding on a discrete video card.

I have no explanation for the CPU processing slower when there is no GPU task. If I understand it right, each core of the A10-xxxx type series shares a floating point processor with another core. So basically Intel will process faster because it has 1 Floating point processor for each core.

My understanding is that the new (Threadripper) AMD cpu's have one floating point processor for each core.

Tom
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Questions and Answers : GPU applications : When should you not use a GPU for processing?


 
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