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 V2 4/6] vhost_net: determine whether or not to use zerocopy at one time
Date: Fri, 30 Aug 2013 12:29:20 +0800 [thread overview]
Message-ID: <1377836962-49780-5-git-send-email-jasowang@redhat.com> (raw)
In-Reply-To: <1377836962-49780-1-git-send-email-jasowang@redhat.com>
Currently, even if the packet length is smaller than VHOST_GOODCOPY_LEN, if
upend_idx != done_idx we still set zcopy_used to true and rollback this choice
later. This could be avoided by determine zerocopy once by checking all
conditions at one time before.
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/vhost/net.c | 46 +++++++++++++++++++---------------------------
1 files changed, 19 insertions(+), 27 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 8a6dd0d..ff60c2a 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -404,43 +404,35 @@ static void handle_tx(struct vhost_net *net)
iov_length(nvq->hdr, s), hdr_size);
break;
}
- zcopy_used = zcopy && (len >= VHOST_GOODCOPY_LEN ||
- nvq->upend_idx != nvq->done_idx);
+
+ zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
+ && (nvq->upend_idx + 1) % UIO_MAXIOV != nvq->done_idx
+ && vhost_net_tx_select_zcopy(net);
/* use msg_control to pass vhost zerocopy ubuf info to skb */
if (zcopy_used) {
+ struct ubuf_info *ubuf;
+ ubuf = nvq->ubuf_info + nvq->upend_idx;
+
vq->heads[nvq->upend_idx].id = head;
- if (!vhost_net_tx_select_zcopy(net) ||
- len < VHOST_GOODCOPY_LEN) {
- /* copy don't need to wait for DMA done */
- vq->heads[nvq->upend_idx].len =
- VHOST_DMA_DONE_LEN;
- msg.msg_control = NULL;
- msg.msg_controllen = 0;
- ubufs = NULL;
- } else {
- struct ubuf_info *ubuf;
- ubuf = nvq->ubuf_info + nvq->upend_idx;
-
- vq->heads[nvq->upend_idx].len =
- VHOST_DMA_IN_PROGRESS;
- ubuf->callback = vhost_zerocopy_callback;
- ubuf->ctx = nvq->ubufs;
- ubuf->desc = nvq->upend_idx;
- msg.msg_control = ubuf;
- msg.msg_controllen = sizeof(ubuf);
- ubufs = nvq->ubufs;
- kref_get(&ubufs->kref);
- }
+ vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
+ ubuf->callback = vhost_zerocopy_callback;
+ ubuf->ctx = nvq->ubufs;
+ ubuf->desc = nvq->upend_idx;
+ msg.msg_control = ubuf;
+ msg.msg_controllen = sizeof(ubuf);
+ ubufs = nvq->ubufs;
+ kref_get(&ubufs->kref);
nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
- } else
+ } else {
msg.msg_control = NULL;
+ ubufs = NULL;
+ }
/* TODO: Check specific error and bomb out unless ENOBUFS? */
err = sock->ops->sendmsg(NULL, sock, &msg, len);
if (unlikely(err < 0)) {
if (zcopy_used) {
- if (ubufs)
- vhost_net_ubuf_put(ubufs);
+ vhost_net_ubuf_put(ubufs);
nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
% UIO_MAXIOV;
}
--
1.7.1
next prev parent reply other threads:[~2013-08-30 4:41 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-30 4:29 [PATCH V2 0/6] vhost code cleanup and minor enhancement Jason Wang
2013-08-30 4:29 ` [PATCH V2 1/6] vhost_net: make vhost_zerocopy_signal_used() returns void Jason Wang
2013-09-02 5:51 ` Michael S. Tsirkin
2013-09-02 6:29 ` Jason Wang
2013-08-30 4:29 ` [PATCH V2 2/6] vhost_net: use vhost_add_used_and_signal_n() in vhost_zerocopy_signal_used() Jason Wang
2013-09-02 5:50 ` Michael S. Tsirkin
2013-09-02 6:28 ` Jason Wang
2013-08-30 4:29 ` [PATCH V2 3/6] vhost: switch to use vhost_add_used_n() Jason Wang
2013-08-30 4:29 ` Jason Wang [this message]
2013-08-30 18:35 ` [PATCH V2 4/6] vhost_net: determine whether or not to use zerocopy at one time Sergei Shtylyov
2013-09-02 3:15 ` Jason Wang
2013-08-30 4:29 ` [PATCH V2 5/6] vhost_net: poll vhost queue after marking DMA is done Jason Wang
2013-08-30 16:44 ` Ben Hutchings
2013-09-02 3:06 ` Jason Wang
2014-02-12 7:38 ` Qin Chuanyu
2014-02-12 10:06 ` Jason Wang
2014-02-12 16:01 ` Michael S. Tsirkin
2013-08-30 4:29 ` [PATCH V2 6/6] vhost_net: correctly limit the max pending buffers Jason Wang
2013-09-02 5:56 ` Michael S. Tsirkin
2013-09-02 6:30 ` Jason Wang
2013-09-02 8:37 ` Jason Wang
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