From: Dario Faggioli <dfaggioli@suse.com>
To: Wanpeng Li <kernellwp@gmail.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Thomas Gleixner" <tglx@linutronix.de>
Subject: Re: [PATCH] KVM: Disable wake-affine vCPU process to mitigate lock holder preemption
Date: Thu, 01 Aug 2019 14:57:50 +0200 [thread overview]
Message-ID: <04700afaf68114b5ab329f5a5182e21578c15795.camel@suse.com> (raw)
In-Reply-To: <1564479235-25074-1-git-send-email-wanpengli@tencent.com>
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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...
Regards
--
Dario Faggioli, Ph.D
http://about.me/dario.faggioli
Virtualization Software Engineer
SUSE Labs, SUSE https://www.suse.com/
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next prev parent reply other threads:[~2019-08-01 12:57 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-30 9:33 [PATCH] KVM: Disable wake-affine vCPU process to mitigate lock holder preemption Wanpeng Li
2019-07-30 11:46 ` Paolo Bonzini
2019-08-01 12:39 ` Dario Faggioli
2019-07-30 12:09 ` Peter Zijlstra
2019-08-01 12:57 ` Dario Faggioli [this message]
2019-08-02 0:51 ` Wanpeng Li
2019-08-02 8:30 ` Christophe de Dinechin
2019-08-02 8:38 ` Paolo Bonzini
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