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skylake CPU numa clustering settting discussion
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Description

The new skylake CPU line has a setting that @RobH noticed when reviewing the CPU settings during cloudvirt1024 setup on T199125.

These new CPUs have a (disabled by default) flag called 'Sub NUMA Cluster' The info on this is here: https://en.wikichip.org/wiki/intel/microarchitectures/skylake_(server)#Sub-NUMA_Clustering

Right now it is disabled by default, but this may be beneficial, and either way we ideally have a review of if its good/bad/or indifferent for us. For now, we're leaving it to the default, which is 'disabled'.

Event Timeline

RobH triaged this task as Medium priority.Oct 17 2018, 6:02 PM
RobH created this task.
Restricted Application added a subscriber: Aklapper. · View Herald TranscriptOct 17 2018, 6:02 PM
bd808 added a subscriber: bd808.Oct 17 2018, 6:11 PM

Some reading on OpenStack and NUMA:

TL;DR from me is that for this to be useful in cloudvirts we would need to setup specific config for the scheduler to be aware of the capabilities and allow instances to be targeted for potentially higher performance via cpu pinning. This seems like a very specialty thing that is more likely to be desired for non-cloud servers where we have a very defined workload and are trying to squeeze all of the performance we can out of the hardware.