lkml.org 
[lkml]   [2019]   [Aug]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] KVM: Disable wake-affine vCPU process to mitigate lock holder preemption
Date

Dario Faggioli writes:

> On Tue, 2019-07-30 at 17:33 +0800, Wanpeng Li wrote:
>> However, in multiple VMs over-subscribe virtualization scenario, it
>> increases
>> the probability to incur vCPU stacking which means that the sibling
>> vCPUs from
>> the same VM will be stacked on one pCPU. I test three 80 vCPUs VMs
>> running on
>> one 80 pCPUs Skylake server(PLE is supported), the ebizzy score can
>> increase 17%
>> after disabling wake-affine for vCPU process.
>>
> Can't we achieve this by removing SD_WAKE_AFFINE from the relevant
> scheduling domains? By acting on
> /proc/sys/kernel/sched_domain/cpuX/domainY/flags, I mean?
>
> Of course this will impact all tasks, not only KVM vcpus. But if the
> host does KVM only anyway...

Even a host dedicated to KVM has many non-KVM processes. I suspect an
increasing number of hosts will be split between VMs and containers.

>
> Regards


--
Cheers,
Christophe de Dinechin

\
 
 \ /
  Last update: 2019-08-02 10:30    [W:0.058 / U:2.840 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site