Re: [virtio-dev] Re: [PATCH v2 0/4] virtio: Clean up scatterlists and use the DMA API

Christian Borntraeger
2014-08-28T19:18:46Z

On 28/08/14 21:03, Andy Lutomirski wrote:
> [removed virtio-dev -- I'm sick of bounces]
>
> On Thu, Aug 28, 2014 at 11:55 AM, Paolo Bonzini <pbonzini@redhat.com> wrote:
>> Il 28/08/2014 20:29, Christian Borntraeger ha scritto:
>>>>>>> block seems to work, with net a simple ping works, iperf causes this:
>>>>>
>>>>> I neither see the bug, nor can I reproduce it on x86_64 on KVM. I
>>>>> doubt that dma vs. non-dma is relevant. I tried -net user a -net tap
>>>>> with iperf running in both directions. I also tried switching
>>>>> virtio_pci into non-DMA-API mode. No errors.
>>>>>
>>>>> Is there any chance that you could instrument that BUG_ON to print n,
>>>>> i, in_sgs, out_sgs, total_sg, total_in, and total_out? I assume this
>>>>> is some oddity with patch 1, but I'm mystified.
>>> Yes, its triggered by patch 1.
>>
>> What version of QEMU? Can you two cat the "features" file in the
>> virtio-net device's sysfs directory?
>
> With vhost=on:
>
> # cat /sys/class/net/eth0/device/features
> 0000011000000001111101010001110000000000000000000000000000000000
>
> Without vhost=on:
>
> # cat /sys/class/net/eth0/device/features
> 0000011000000001111101010001110000000000000000000000000000000000
>
> Instrumenting the code says that indirect=1.
>
> --Andy
>

I have

1100011111111111111101010001110000000000000000000000000000000000