On Tue, Nov 23, 2010 at 08:20:19AM +0200, Avi Kivity wrote: > 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. > And IIRC we do have option to disable MSIX in qemu. I just don't remember how it looks. Michael? -- 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
