From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: x86: use smp_send_reschedule in kvm_vcpu_kick
Date: Thu, 12 Mar 2009 13:04:22 +0200
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Cc: Avi Kivity <avi@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>,
	Ingo Molnar <mingo@elte.hu>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	Peter Zijlstra <peter@programming.kicks-ass.net>
To: "Zhang, Xiantao" <xiantao.zhang@intel.com>
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On Thu, Mar 12, 2009 at 10:31:47AM +0800, Zhang, Xiantao wrote:
> Avi Kivity wrote:
> > Marcelo Tosatti wrote:
> >> OK, reworked patch:
> >> - change ia64 in addition to x86
> >> - add comment on smp send reschedule handlers about KVM's usage
> >> 
> >> Untested on IA64.
> >> 
> >> KVM: use smp_send_reschedule in kvm_vcpu_kick
> >> 
> >> KVM uses a function call IPI to cause the exit of a guest running on
> >> a physical cpu. For virtual interrupt notification there is no need
> >> to wait on IPI receival, or to execute any function.
> >> 
> >> This is exactly what the reschedule IPI does, without the overhead
> >> of function IPI. So use it instead of smp_call_function_single in
> >> kvm_vcpu_kick. 
> >> 
> >> Also change the "guest_mode" variable to a bit in vcpu->requests, and
> >> use that to collapse multiple IPI's that would be issued between the
> >> first one and zeroing of guest mode.
> >> 
> >> This allows kvm_vcpu_kick to called with interrupts disabled.
> >> 
> > 
> > Looks good. Will wait for Xiantao's test-n-ack before applying.
> 
> kvm-ia64 is broken due to recent check-ins about irq-bits, and we are trying to fix it. For this patch, ia64 has to export the symbol smp_send_reschedule before applying the patch.
Can you try this patch please: http://patchwork.kernel.org/patch/11103/

--
			Gleb.