On Wed, 10 Aug 2016 17:47:16 +0300 "Michael S. Tsirkin" <m...@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.h...@de.ibm.com> > Cc: Jason Wang <jasow...@redhat.com> > Suggested-by: Patrik Hermansson <phermans...@gmail.com> > Signed-off-by: Michael S. Tsirkin <m...@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.h...@de.ibm.com>
