Re: [Qemu-devel] [PATCH v2] virtio-net: allow increasing rx queue size

[Jason Wang <jasowang@redhat.com>]

On 2016年08月11日 19:48, Cornelia Huck wrote:
> On Wed, 10 Aug 2016 17:47:16 +0300
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
>
>> This allows increasing the rx queue size up to 1024: unlike with tx,
>> guests don't put in huge S/G lists into RX so the risk of running into
>> the max 1024 limitation due to some off-by-one seems small.
>>
>> It's helpful for users like OVS-DPDK which don't do any buffering on the
>> host - 1K roughly matches 500 entries in tun + 256 in the current rx
>> queue, which seems to work reasonably well. We could probably make do
>> with ~750 entries but virtio spec limits us to powers of two.
>> It might be a good idea to specify an s/g size limit in a future
>> version.
>>
>> It also might be possible to make the queue size smaller down the road, 64
>> seems like the minimal value which will still work (as guests seem to
>> assume a queue full of 1.5K buffers is enough to process the largest
>> incoming packet, which is ~64K).  No one actually asked for this, and
>> with virtio 1 guests can reduce ring size without need for host
>> configuration, so don't bother with this for now.
>>
>> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
>> Cc: Jason Wang <jasowang@redhat.com>
>> Suggested-by: Patrik Hermansson <phermansson@gmail.com>
>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>> ---
>>
>> changes from v1:
>>      add macros as suggested by Cornelia
>>
>>   include/hw/virtio/virtio-net.h |  1 +
>>   hw/net/virtio-net.c            | 26 +++++++++++++++++++++++++-
>>   2 files changed, 26 insertions(+), 1 deletion(-)
> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
>
>
>

Queued in net-next (for 2.8)

Thanks