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Hi Michael,
I hope this message finds you well.
I have 2 questions about crunching on PPS Sieve CUDA
a) Why is the GPU LOAD so irregular , almost sinusoidal ?
=> in order to avoid "sinusoidal use" of the GPU, I run 2 WU's at the same time => GPU LOAD is almost stable.
b) CPU Time : During a long period of time, the CPU time of a single WU was approx 25 %.
Then it jumped to almost 50 %. Today, I realise the CPU time decreased again to approx 25 % , together with a shorter GPU calculation time.
Are there any particular reasons to explain these 2 points ?
Thank You very much,
Kind Regards,
Philippe |
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NB : Point b) apparently only valid for my GTX770 / i7 4770K and not the GTX660Ti / AMD Phenom II X4 955 |
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Theory on (b): Your 4770K has hyperthreading turned on. Each CPU thread is therefore only half as "capable", and so CPU usage percentage on a single thread for a GPU job will appear to double. AMD CPUs do not implement hyperthreading.
That's my take on this. If I've misunderstood your observations, my apologies.
--Gary |
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Hi Gary,
Thank you for your message.
However, the CPU time changed from 25 % -> 50 % -> 25 % (of GPU time)
with HT on all the time.
I switched HT Off only once, to run AVX WU - GFN Short I believe, during the last GFN challenge.
Thank You
Kind Regards,
Philippe
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Hi !
No worries, forget it. It runs very well now.
Fine for me.
Thank You
Philippe |
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Was a change made to the pps sieve tasks to double check more tasks or am I just getting an abnormal number of units requiring the quorum of 2 or are my systems now more suspect for some reason?
Cheers Rick
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@AggieThePew
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Missing factors were found therefore PrimeGrid is doing a doublecheck on the range from 0P to 1P.
Wait for JimB explanation....
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 Michael Goetz Volunteer moderator
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Missing factors were found therefore PrimeGrid is doing a doublecheck on the range from 0P to 1P.
Wait for JimB explanation....
That pretty much sums it up. We're now doing full double checking on PPS-Sieve, so two tasks will be generated for each WU right from the start.
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My lucky number is 75898524288+1 |
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Thanks. Was just curious. I do remember the notes on the discovered issues with lots of work done in the past.
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@AggieThePew
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It appears my factor rate is climbing... maybe |
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TylerProject administrator
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How can i configure BOINC to run 2 pps sieve tasks at a time on my GTX 760? My GPU usage is constantly bobbing between 98% and 72%
Thank you,
-1998golfer
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275*2^3585539+1 is prime!!! (1079358 digits)
 Proud member of Aggie the Pew
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I am getting the same GPU load fluctuation on my GTX 680. This causes my fan to speed up then slow down in time with the GPU load. It got annoying so I set the fan to run at a set speed fast enough to keep things semi cool.
Good question 1998golfer, I have yet to figure that out myself. Its not anything I can find in the project settings or in the Boinc client. Then again I am probably overlooking something obvious like normal. |
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TylerProject administrator
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I am getting the same GPU load fluctuation on my GTX 680. This causes my fan to speed up then slow down in time with the GPU load. It got annoying so I set the fan to run at a set speed fast enough to keep things semi cool.
Good question 1998golfer, I have yet to figure that out myself. Its not anything I can find in the project settings or in the Boinc client. Then again I am probably overlooking something obvious like normal.
I have since figured it out.
Here is how to do it:(assuming you are on windows)
In your BOINC data directory, go to projects then www.primegrid.com
In that folder, create a new file and call it app_config.xml
Inside that file, put the following:
<app_config>
<app>
<name>pps_sr2sieve</name>
<max_concurrent>2</max_concurrent>
<gpu_versions>
<gpu_usage>0.5</gpu_usage>
<cpu_usage>0.05</cpu_usage>
</gpu_versions>
</app>
</app_config>
Save the file, reboot your computer. open boinc and it should run two PPS Sieve tasks at once.
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275*2^3585539+1 is prime!!! (1079358 digits)
Proud member of Aggie the Pew
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compositeVolunteer tester
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Thanks for that app_config.xml file. It also works in Linux, boosting output of a single GTX 760 by 17%, doing 2 PPS sieve WU in 1327 sec whereas previously it did 1 WU in 803 sec. The GPU runs hotter now by a few degrees, up to 70 C now.
Be sure to give BOINC enough CPU cores to run GPU tasks along with CPU tasks. I set mine to 55% of max to prevent LLR from using HT but allowing multiple GPU tasks to run.
You shouldn't need to reboot to activate the new settings, just use the BOINC manager advanced menu item "Read config files".
If your desktop acts sluggish, exiting the BOINC manager without stopping the running tasks improves things significantly (in Linux).
I'm trying it with 4 simultaneous WU to see what happens to runtime. The 4 WU and desktop altogether use less that 500 MB of GPU memory, and GPU temperature has risen to 71 C. |
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compositeVolunteer tester
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I'm trying it with 4 simultaneous WU to see what happens to runtime. The 4 WU and desktop altogether use less that 500 MB of GPU memory, and GPU temperature has risen to 71 C.
I observe practically no difference between running 2 WU and 4 WU on the same GPU. The average observed runtime is 41 seconds less per WU with 4 WU compared to 2 WU, but that is within the normal variation in runtimes I see with just 2 WU, in effect a total difference of about 2 PPS sieve WU per day.
This was not a high-precision comparison. BOINC was also running 4 PPS LLR at the same time, the BOINC manager was not running, and the usual assortment of Linux GUI and file services was running, including Xorg with Cinnamon desktop (using about 3% of one i7-920 core).
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