Re: [PATCH RESEND v8 1/2] sched/numa: introduce per-cgroup NUMA locality info

From: Peter Zijlstra
Date: Fri Feb 21 2020 - 10:28:50 EST

On Mon, Feb 17, 2020 at 09:23:52PM +0800, çè wrote:
> FYI, by monitoring locality, we found that the kvm vcpu thread is not
> covered by NUMA Balancing, whatever how many maximum period passed, the
> counters are not increasing, or very slowly, although inside guest we are
> copying memory.
> Later we found such task rarely exit to user space to trigger task
> work callbacks, and NUMA Balancing scan depends on that, which help us
> realize the importance to enable NUMA Balancing inside guest, with the
> correct NUMA topo, a big performance risk I'll say :-P

That's a bug in KVM, see:

ISTR there being newer versions of that patch-set, but I can't seem to
find them in a hurry.