Re: [PATCH v2] sched/nohz: Optimize get_nohz_timer_target()

From: Thomas Gleixner
Date: Wed Oct 23 2019 - 04:29:24 EST


On Wed, 23 Oct 2019, Wanpeng Li wrote:
> I didn't see your refactor to get_nohz_timer_target() which you
> mentioned in IRC after four months, I can observe cyclictest drop from
> 4~5us to 8us in kvm guest(we offload the lapic timer emulation to
> housekeeping cpu to avoid timer fire external interrupt on the pCPU
> which vCPU resident incur a vCPU vmexit) w/o this patch in the case of
> there is no busy housekeeping cpu. The score can be recovered after I
> give stress to create a busy housekeeping cpu.
>
> Could you consider applying this patch for temporary since I'm not
> sure when the refactor can be ready.

Yeah. It's delayed (again).... Will pick that up.

Thanks,

tglx