linux-kernel - Re: [PATCH v2 2/3] KVM: dynamic halt_poll

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Message-ID: <BLU436-SMTP163A71F77F070557F72158480600@phx.gbl>
Date:	Wed, 26 Aug 2015 17:12:48 +0800
From:	Wanpeng Li <wanpeng.li@...mail.com>
To:	David Matlack <dmatlack@...gle.com>
CC:	Paolo Bonzini <pbonzini@...hat.com>,
	kvm list <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/3] KVM: dynamic halt_poll_ns adjustment

On 8/26/15 1:19 AM, David Matlack wrote:
> Thanks for writing v2, Wanpeng.
>
> On Mon, Aug 24, 2015 at 11:35 PM, Wanpeng Li <wanpeng.li@...mail.com> wrote:
>> There is a downside of halt_poll_ns since poll is still happen for idle
>> VCPU which can waste cpu usage. This patch adds the ability to adjust
>> halt_poll_ns dynamically.
> What testing have you done with these patches? Do you know if this removes
> the overhead of polling in idle VCPUs? Do we lose any of the performance
> from always polling?

There is 0.8% kernel compile performance improvement(10 iterations) on 
host w/ 800 idle vCPUs. Btw, I handle all your comments in v3. Many 
thanks for your review, David! :-)

Regards,
Wanpeng Li
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