In the following app_config, what does the 0.1 mean?
Does it mean that the max cpu each gpu can use is .1
or the max cpu each wu within each gpu can use is .1
or the cpu of .1 of each unless more cpu is available?

Hope you can understand what I wrote.


app_config>
<app>
<name>astropulse_v6</name>
<gpu_versions>
<gpu_usage>.33</gpu_usage>
<cpu_usage>0.1</cpu_usage>
</gpu_versions>
</app>
</app_config>

The 0.1 is is the maximum CPU usage that a GPU based task is allowed to use. Some CPU usage is needed to feed data to the GPU and do parts of the processing that are very inefficient on the GPU.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Thanks Rob. Now at last I'm clear on that point.

This value do not tell anything to the app, it is only info for BOINC

With 0.1 BOINC will not do anything until the sum is >= 1
This means BOINC will run one less CPU task only after it started 10 GPU tasks 10*0.1 = 1

Again: 0.1 do not limit app to use 0.1 CPU nor it is possible for BOINC to reserve part of CPU core
BOINC do not regulate the CPU usage of any app (if 'use 100% CPU time' is set in Preferences), BOINC only starts the app and do not manage its CPU usage after that

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- ALF - "Find out what you don't do well ..... then don't do it!" :)
 

So this means, if I have 3 gpu's with 3 tasks each for a total of 9 and I have my boinc set to run 87.5%(7 of 8 threads)of my CPU's;

it makes no difference if I set this parameter to .1 or .04. There will be no difference to how my app's run.

 
Yes, no difference

If it is 0.112 this will 'free a core' (one less CPU task): 0.112*9 = 1.008 = 1
If it is 0.222 - again only 'one less CPU task': 0.222*9 = 1.998 = 1 (result is truncated to integer, not rounded)

(the above "free a core|one less CPU task" is in addition to what is already freed by "use at most XX% of the processors")


P.S.
For the 'On multiprocessors, use at most XX% of the processors' you don't necessarily need exact values like 87.5%
Anything 87.5% ... 99% will 'free a core' (99 is easier to type; on any CPU with up to 100 cores this will make BOINC to run one less CPU task)
Anything 75% ... 87.4% will 'free 2 cores' (on 8-core CPU)
etc

8 * 0.99 = 7.92 = 7 (BOINC is allowed to run only up to 7 CPU tasks)
8 * 0.88 = 7.04 = 7
8 * 0.87 = 6.96 = 6
8 * 0.77 = 6.16 = 6
 

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- ALF - "Find out what you don't do well ..... then don't do it!" :)
 

Thanks BilBg!