From: Jason Wang <jasowang@redhat.com>
To: mst@redhat.com, kvm@vger.kernel.org,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Jason Wang <jasowang@redhat.com>
Subject: [PATCH V3 2/6] vhost_net: use vhost_add_used_and_signal_n() in vhost_zerocopy_signal_used()
Date: Mon, 2 Sep 2013 16:40:57 +0800 [thread overview]
Message-ID: <1378111261-14826-3-git-send-email-jasowang@redhat.com> (raw)
In-Reply-To: <1378111261-14826-1-git-send-email-jasowang@redhat.com>
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>
---
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 280ee66..8a6dd0d 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)
--
1.7.1
next prev parent reply other threads:[~2013-09-02 8:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-02 8:40 [PATCH V3 0/6] vhost code cleanup and minor enhancement Jason Wang
2013-09-02 8:40 ` [PATCH V3 1/6] vhost_net: make vhost_zerocopy_signal_used() return void Jason Wang
2013-09-02 8:40 ` Jason Wang [this message]
2013-09-02 8:40 ` [PATCH V3 3/6] vhost: switch to use vhost_add_used_n() Jason Wang
2013-09-02 8:40 ` [PATCH V3 4/6] vhost_net: determine whether or not to use zerocopy at one time Jason Wang
2013-09-04 11:59 ` Michael S. Tsirkin
2013-09-05 2:54 ` Jason Wang
2013-09-23 7:16 ` Michael S. Tsirkin
2013-09-26 4:30 ` Jason Wang
2013-09-29 9:36 ` Jason Wang
2013-09-02 8:41 ` [PATCH V3 5/6] vhost_net: poll vhost queue after marking DMA is done Jason Wang
2013-09-02 8:41 ` [PATCH V3 6/6] vhost_net: correctly limit the max pending buffers Jason Wang
2013-09-04 2:47 ` [PATCH V3 0/6] vhost code cleanup and minor enhancement David Miller
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