From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: [PATCH V3 4/6] vhost_net: determine whether or not to use zerocopy at one time Date: Mon, 2 Sep 2013 16:40:59 +0800 Message-ID: <1378111261-14826-5-git-send-email-jasowang@redhat.com> References: <1378111261-14826-1-git-send-email-jasowang@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: mst@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Return-path: In-Reply-To: <1378111261-14826-1-git-send-email-jasowang@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org 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 determining zerocopy once by checking all conditions at one time before. Signed-off-by: Jason Wang --- drivers/vhost/net.c | 47 ++++++++++++++++++++--------------------------- 1 files changed, 20 insertions(+), 27 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 8a6dd0d..3f89dea 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -404,43 +404,36 @@ 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