From: Gleb Natapov <gleb@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: mtosatti@redhat.com, kvm@vger.kernel.org
Subject: Re: [PATCH] KVM: emulator: do not needlesly sync registers from emulator ctxt to vcpu
Date: Wed, 30 Mar 2011 14:48:28 +0200 [thread overview]
Message-ID: <20110330124828.GX7766@redhat.com> (raw)
In-Reply-To: <4D931F73.90704@redhat.com>
On Wed, Mar 30, 2011 at 02:17:55PM +0200, Avi Kivity wrote:
> On 03/30/2011 01:43 PM, Gleb Natapov wrote:
> >After reboot perf started to work. I ran modified emulator.flat unit
> >test. It was modified to run test_cmps() in an endless loop.
> >
> >Without patch:
> >1.71% qemu-system-x86 [kvm] [k] x86_emulate_instruction
> >1.51% qemu-system-x86 [kvm] [k] x86_emulate_instruction
> >1.68% qemu-system-x86 [kvm] [k] x86_emulate_instruction
> >
> >With patch:
> >0.84% qemu-system-x86 [kvm] [k] x86_emulate_instruction
> >0.96% qemu-system-x86 [kvm] [k] x86_emulate_instruction
> >0.89% qemu-system-x86 [kvm] [k] x86_emulate_instruction
> >
>
> The cause might be kvm_rip_write() using vmwrite. Can you use perf
> to see where the hits are in x86_emulate_instruction?
>
> If that's the case, we may be able to do local optimizations to
> kvm_rip_write(), kvm_set_rflags(), and toggle_interruptiblity()
> instead of this global change.
>
I can leave copying there and eliminate only kvm_rip_write and see
perf data.
--
Gleb.
next prev parent reply other threads:[~2011-03-30 12:48 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-29 12:08 [PATCH] KVM: emulator: do not needlesly sync registers from emulator ctxt to vcpu Gleb Natapov
2011-03-30 10:38 ` Avi Kivity
2011-03-30 10:47 ` Gleb Natapov
2011-03-30 10:50 ` Avi Kivity
2011-03-30 11:22 ` Gleb Natapov
2011-03-30 11:43 ` Gleb Natapov
2011-03-30 12:12 ` Avi Kivity
2011-03-30 12:12 ` Avi Kivity
2011-03-30 12:17 ` Avi Kivity
2011-03-30 12:48 ` Gleb Natapov [this message]
2011-03-30 13:26 ` Gleb Natapov
2011-03-30 13:29 ` Avi Kivity
2011-03-30 13:36 ` Gleb Natapov
2011-03-30 13:41 ` Avi Kivity
2011-03-30 13:43 ` Gleb Natapov
2011-03-30 13:46 ` Avi Kivity
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