linux-kernel - Re: [PATCH v5] KVM: halt-polling: poll for the upcoming fire timers

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Message-ID: <20160526133331.5aadf122@jnakajim-build>
Date:	Thu, 26 May 2016 13:33:31 -0700
From:	yunhong jiang <yunhong.jiang@...ux.intel.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	Wanpeng Li <kernellwp@...il.com>, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, Wanpeng Li <wanpeng.li@...mail.com>,
	Radim Krčmář <rkrcmar@...hat.com>,
	David Matlack <dmatlack@...gle.com>,
	Christian Borntraeger <borntraeger@...ibm.com>,
	Yang Zhang <yang.zhang.wz@...il.com>
Subject: Re: [PATCH v5] KVM: halt-polling: poll for the upcoming fire timers

On Thu, 26 May 2016 12:26:27 +0200
Paolo Bonzini <pbonzini@...hat.com> wrote:

> 
> 
> On 25/05/2016 04:47, Wanpeng Li wrote:
> > From: Wanpeng Li <wanpeng.li@...mail.com>
> > 
> > If an emulated lapic timer will fire soon(in the scope of 10us the
> > base of dynamic halt-polling, lower-end of message passing workload
> > latency TCP_RR's poll time < 10us) we can treat it as a short halt,
> > and poll to wait it fire, the fire callback apic_timer_fn() will set
> > KVM_REQ_PENDING_TIMER, and this flag will be check during busy poll.
> > This can avoid context switch overhead and the latency which we wake
> > up vCPU.
> 
> As discussed on IRC, I would like to understand why the adaptive

Glad to know the IRC channel. Is #kvm channel on freenode the IRC you are
talking about?

Thanks
--jyh