On 03/30/2011 01:43 PM, Gleb Natapov wrote:
> > The patch saves copying of 256 bytes on each MMIO/PIO read. It may not > save a lot comparing to time it takes to do one MMIO to userspace, but > do 1 million of those and you saved a lot of CPU cycles. I do not think > we should abandon the optimization so easily. Unfortunately I can't run > perf on 2.6.38 kernel right now. It gives me strange errors and when it > doesn't it makes kernel OOPS. > 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
Well, that is probably significant. -- error compiling committee.c: too many arguments to function -- 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
