CPU scheduler granularity - performance impact?
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Is there any performance impact on choosing core or CPU mode?
My case: an application that can use maximum 16 threads. I have a 24 core EPYC system. Would Core mode would be better, as each thread could end up on a separate core, or would that be worse due to cache-misses etc?
https://xcp-ng.org/docs/release-8-2.html#core-scheduling-experimental
Look at the Docs it doesn't clearly say, but I think that core or socket would give best computing power to as single VM on that server?
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Yes, there is. Core scheduling might be better in very specific scenario, but IMHO it's not mature enough for now to be more powerful.
So except in a tight security environment, you shouldn't use it. However, providing some benchmarks will be wonderful so we can have factual results instead of just my feeling
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@olivierlambert said in CPU scheduler granularity - performance impact?:
Yes, there is. Core scheduling might be better in very specific scenario, but IMHO it's not mature enough for now to be more powerful.
So except in a tight security environment, you shouldn't use it. However, providing some benchmarks will be wonderful so we can have factual results instead of just my feeling
In this case I wanted to dedicate one of the physical server to one application, so from a security point of view it should be OK. No internet access and all that
Is the scheduler host dependent, or is it set for the pool? I have two identical servers I could enable Core on one and CPU on the other and then run some benchmarks. Any specific benchmark you'd prefer?
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So no need to do this.
You can also do CPU pinning at some point if you really want to have a "fixed" VM on dedicated cores only for it.
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@olivierlambert said in CPU scheduler granularity - performance impact?:
You can also do CPU pinning at some point if you really want to have a "fixed" VM on dedicated cores only for it.
Do you mean pinning as explained here? https://xcp-ng.org/docs/compute.html#advanced-xen
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Yes, more explanation here: https://support.citrix.com/article/CTX246466
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