it ready caused by the the MSIX mask bit.
so i disable the msix in the newer virtio driver, and i found it have
better performent than msix enabled. the cpu rate of host os reduce.
the reason maybe is ept violation.
I couldn't use newer kernels. because the purpose i used kvm is run
old software on new hardware.
but i think this is a common problem, maybe newer kernel also exist.
i think we should not enable msi for virtio.
if anybody also interest on this problem, you can do the same test.
I disalbe msi by modify the function vp_find_vqs like this:
static int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,
struct virtqueue *vqs[],
vq_callback_t *callbacks[],
const char *names[])
{
#if 0
int err;
/* Try MSI-X with one vector per queue. */
err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names, true, true);
if (!err)
return 0;
/* Fallback: MSI-X with one vector for config, one shared for queues. */
err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,
true, false);
if (!err)
return 0;
/* Finally fall back to regular interrupts. */
#endif
return vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,
false, false);
}
2010/11/15, lidong chen <chen.lidong.kernel@xxxxxxxxx>:
> I think the address maybe initialized in function virtio_pci_probe.
> err = pci_request_regions(pci_dev, "virtio-pci");
>
> but i did not know when used this address.
>
>
> 2010/11/15, lidong chen <chen.lidong.kernel@xxxxxxxxx>:
>> 2010/11/15, Avi Kivity <avi@xxxxxxxxxx>:
>>> On 11/15/2010 09:24 AM, lidong chen wrote:
>>>> the address is the Region 1 of virtio_net.
>>>>
>>>> why virtio_net use this address caused ept violation?
>>>
>>> It's probably the MSIX mask bit. Older kernels program this bit twice
>>> on every interrupt. Newer kernels do this much less frequently. Try
>>> with a new kernel and see.
>>>
>>> --
>>> error compiling committee.c: too many arguments to function
>>>
>>>
>>
>
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