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(parent: 51be7a9) | patch
vhost: try avoiding avail index access when getting descriptor
authorJason Wang <jasowang@redhat.com>
Tue, 7 Feb 2017 07:49:50 +0000 (15:49 +0800)
committerMichael S. Tsirkin <mst@redhat.com>
Mon, 27 Feb 2017 18:37:27 +0000 (20:37 +0200)
commite3b56cdd4351f0e227d4d847eeadff4c82aef1b9
tree45d602addb89b2cd3cf1617ecb85275dad7d3f9etree | snapshot (tar.gz zip)
parent51be7a9a261ce18c520fb3928b168feb77522745commit | diff
vhost: try avoiding avail index access when getting descriptor

If last avail idx is not equal to cached avail idx, we're sure there's
still available buffers in the virtqueue so there's no need to re-read
avail idx. So let's skip this to avoid unnecessary userspace memory
access and memory barrier. Pktgen test show about 3% improvement on rx
pps.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
drivers/vhost/vhost.c diff | blob | blame | history