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| author | Jason Wang <jasowang@redhat.com> | 2013-09-02 16:40:57 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-09-03 22:46:57 -0400 |
| commit | c92112aed3f0b14fdd2dbd9f192cce1af22c0e1c (patch) | |
| tree | ee7b35d59a5ab61b295e33087862b381481ed292 | |
| parent | 094afe7d556428a2ce2df0f6a4b333f7ba4d74d5 (diff) | |
| download | linux-c92112aed3f0b14fdd2dbd9f192cce1af22c0e1c.tar.bz2 | |
vhost_net: use vhost_add_used_and_signal_n() in vhost_zerocopy_signal_used()
We tend to batch the used adding and signaling in vhost_zerocopy_callback()
which may result more than 100 used buffers to be updated in
vhost_zerocopy_signal_used() in some cases. So switch to use
vhost_add_used_and_signal_n() to avoid multiple calls to
vhost_add_used_and_signal(). Which means much less times of used index
updating and memory barriers.
2% performance improvement were seen on netperf TCP_RR test.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/vhost/net.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 280ee66ae552..8a6dd0d5667c 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -281,7 +281,7 @@ static void vhost_zerocopy_signal_used(struct vhost_net *net, { struct vhost_net_virtqueue *nvq = container_of(vq, struct vhost_net_virtqueue, vq); - int i; + int i, add; int j = 0; for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) { @@ -289,14 +289,17 @@ static void vhost_zerocopy_signal_used(struct vhost_net *net, vhost_net_tx_err(net); if (VHOST_DMA_IS_DONE(vq->heads[i].len)) { vq->heads[i].len = VHOST_DMA_CLEAR_LEN; - vhost_add_used_and_signal(vq->dev, vq, - vq->heads[i].id, 0); ++j; } else break; } - if (j) - nvq->done_idx = i; + while (j) { + add = min(UIO_MAXIOV - nvq->done_idx, j); + vhost_add_used_and_signal_n(vq->dev, vq, + &vq->heads[nvq->done_idx], add); + nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV; + j -= add; + } } static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) |