Core usage capped at 8?

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Message 11202 - Posted: 19 Feb 2012, 21:35:35 UTC

Could it be that the client never uses more then 8 threads regardless is there are more cores present or not?

I noticed that the total CPU usage from blender tops out around what you would expect from 8 threads, so at around 66% with 12 cores for example or 50% with 16 cores.

Digging around in the logs I found this line which gets logged during the initialisation of each WU or so it seems (shortly after the "Compiled with Python ..." line):
"Error, threads has to be in range 1-8"


So is this intended or a known limitation and if yes, is there any way to get boinc to either run two Burp WUs at once (if there is enough RAM ...) or WUs of another project?

Claiming all cores if they can't be used anyway is kinda wasteful. :|
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Message 11203 - Posted: 19 Feb 2012, 21:51:02 UTC - in response to Message 11202.  
Last modified: 19 Feb 2012, 22:02:13 UTC

We don't impose any limits on the number of cores from the BURP side of things (or rather the default is 64 cores), so if there is indeed such a limit it will be in Blender.
The version of Blender used with Sunflower is really old (had to match with the one that was used to make the Big Buck Bunny movie) and the one on the normal farm is pretty old too - so it is quite likely that this limit is no longer in place in the official version of Blender, I'll have to check that
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Message 12002 - Posted: 9 Sep 2013, 14:37:32 UTC - in response to Message 11203.  

We don't impose any limits on the number of cores from the BURP side of things (or rather the default is 64 cores), so if there is indeed such a limit it will be in Blender.
The version of Blender used with Sunflower is really old (had to match with the one that was used to make the Big Buck Bunny movie) and the one on the normal farm is pretty old too - so it is quite likely that this limit is no longer in place in the official version of Blender, I'll have to check that


any hope in opening more than 64-cores? :)
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Message 12003 - Posted: 9 Sep 2013, 17:04:15 UTC - in response to Message 11202.  
Last modified: 9 Sep 2013, 17:05:22 UTC

So is this intended or a known limitation and if yes, is there any way to get boinc to either run two Burp WUs at once (if there is enough RAM ...) or WUs of another project?

Claiming all cores if they can't be used anyway is kinda wasteful. :|

There is a thread which already dealt with that problem here. We discussed the way if and how the SunflowerBlender-app could be used for more cores. I finally found a way and came up with the app_info.xml mentioned here. Maybe you can use that meanwhile, but you need a lot of RAM for that and it's not recommended to run more than two Sunflower-WUs at once anyway.
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Message 12007 - Posted: 10 Sep 2013, 18:12:45 UTC

Turns out that the limit is not in Blender but in the default "multithreading plan class" that comes with BOINC. It caps out at 64 threads and the projects have create custom plan classes to use more than 64 threads.
There was some discussion about this recently on the BOINC mailing list and I think that we will be running some tests with fully unlocked clients once the BBB3D release is out of the way and I get some more spare time to poke at those kind of things again.
Cycles definitely looks like an interesting subject when talking >64 cores. Unfortunately it doesn't change the fact that some of the pre- and postprocessing steps are single-core and that you cannot change the number of allocated cores while mid-ways through a WU so the remaining cores will essentially be wasted during those passes.
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Message boards : Number crunching : Core usage capped at 8?