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. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
