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12 core qmaster cluster sweet spot for best performance?

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Sean Kapleton
12 core qmaster cluster sweet spot for best performance?
on Jan 13, 2011 at 2:53:16 am

I am trying a cluster for the first time on my new 12 core and I am curious about a few things. Its a new 12 core mac pro (32gb ram) what the sweet spot is is what I am curious about. I have used compressor cluster on 8 cores for a few years of post work but I am curious as to what the sweet spot is ( i.e. recommended settings for optimal performance). how many cores to use and how many to leave available for OS etc?

I just did a test setting qmaster to use all 24 cores and right off the bat I notice a problem in the save to folder there are not multiple iterations of that file I used to seeing this when using a cluster. shouldn't I be seeing 24 of these files that will all come together at the end of processing?
In another forum it was suggested to me that I set it to use 10 (20 threads) to see if it gives me an edge. generally, leaving 2 physical cores available is optimal with compressor and after effects multi-core rendering correct?

I do not see multiple sections of the video being encoded in batch monitor. I have "Allow job segmenting" checked in the Encoder tab of my Compressor preset which is just the standard iphone 640 setting so its checked by default anyways. I also made sure to be selecting my cluster when i send the job from compressor.


I fully understand what the multiple copies means, no confusion about threading. I am now trying 20 threads (10 of 12 cores) I do NOT see that happen when I sent the batch even tho it's set to use all 20 threads. what am i doing wrong?!

Also if I am not running any other apps should i still have it set to use 10 of my cores?

any help please?
sean


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Craig Seeman
Re: 12 core qmaster cluster sweet spot for best performance?
on Jan 13, 2011 at 3:11:06 am

I think the safest test to perform is testing the speed vs instances. Try 6 instances and 12 instances to start with and see what the speed difference is on the encode. Then try 8 and then 10. This will give you a rate of change. You may find that, while speed improves, the actual rate of increases decreases. After that try 18 and 24. That will give you the most efficient use of cores.



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Sean Kapleton
Re: 12 core qmaster cluster sweet spot for best performance?
on Jan 13, 2011 at 3:37:01 am

thanks for the reply i guess i was hoping some people would have done tests already and found the sweet spot on this machine.

also the problem stills remains of my system not multi thread cluster processing, here is a screen grab of what activity monitor shows - in the destination folder i only see one copy still.

any help?



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Craig Seeman
Re: 12 core qmaster cluster sweet spot for best performance?
on Jan 13, 2011 at 3:57:06 am

It would probably be better to look at % in Activity Monitor.
Again if you'e looking for a "sweet spot" you have to consider the diminishing returns vs the number of instances.

Unless someone else has the exact same config, their results may not match yours. You need to find the results for your machine.

I don't know if Barefeats has run tests with Compressor on the 12 cores systems but you can see here that there's a point of diminishing returns. Read his comments specific to Compressor.
http://www.barefeats.com/nehal04.html

Older test but again note the pattern.
http://www.barefeats.com/octopro5.html



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