can you tell me something about this problem.
thanks.

2010/11/23 Avi Kivity <avi@redhat.com>:
quoted text
> On 11/23/2010 04:53 AM, lidong chen wrote:
>>
>> Test method:
>> Send the same traffic load between virtio_pci MSI-X disable and
>> enable,and compare the cpu rate of host os.
>> I used the same version of virtio driver, only modify the msi-x option.
>> the host os version is 2.6.32.
>> the virtio dirver is from rhel6.
>> the guest version  os is 2.6.16.
>>
>> Test result:
>> with msi-x disable, the cpu rate of host os is 110%.
>> with msi-x enable, the cpu rate of host os is 140%.
>>
> ...
>
>> Conclusion:
>> msi-x enable waste more cpu resource is caused by MSIX mask bit. In
>> older kernels program this bit twice
>> on every interrupt. and caused ept violation.
>>
>> So I think we should add a param to control this.with older kernels,
>> we should disable MSIX.
>> And I think this should deal by qemu.
>
> There is now work in progress (by Sheng Yang) to speed up mask bit
> emulation, which should improve things.  Also, newer kernels don't hit the
> mask bit so hard.  You might try to backport the mask bit patches to your
> 2.6.16 guest.
>
> --
> I have a truly marvellous patch that fixes the bug which this
> signature is too narrow to contain.
>
>
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