On 03/30/2011 02:12 PM, Avi Kivity wrote:
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.
Please rebase the patch after sse-mmio goes in.
--
error compiling committee.c: too many arguments to function
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