From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752963AbeEUOd5 (ORCPT ); Mon, 21 May 2018 10:33:57 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:36668 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751251AbeEUOdy (ORCPT ); Mon, 21 May 2018 10:33:54 -0400 Date: Mon, 21 May 2018 17:33:52 +0300 From: "Michael S. Tsirkin" To: Jason Wang Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH net-next 12/12] vhost_net: batch submitting XDP buffers to underlayer sockets Message-ID: <20180521173253-mutt-send-email-mst@kernel.org> References: <1526893473-20128-1-git-send-email-jasowang@redhat.com> <1526893473-20128-13-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1526893473-20128-13-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 21, 2018 at 05:04:33PM +0800, Jason Wang wrote: > This patch implements XDP batching for vhost_net with tun. This is > done by batching XDP buffs in vhost and submit them when: > > - vhost_net can not build XDP buff (mostly because of the size of packet) > - #batched exceeds the limitation (VHOST_NET_RX_BATCH). > - tun accept a batch of XDP buff through msg_control and process them > in a batch > > With this tun XDP can benefit from e.g batch transmission during > XDP_REDIRECT or XDP_TX. > > Tests shows 21% improvement on TX pps (from ~3.2Mpps to ~3.9Mpps) > while transmitting through testpmd from guest to host by > xdp_redirect_map between tap0 and ixgbe. > > Signed-off-by: Jason Wang s/underlayer/underlying/ ? > --- > drivers/net/tun.c | 36 +++++++++++++++++---------- > drivers/vhost/net.c | 71 ++++++++++++++++++++++++++++++++++++----------------- > 2 files changed, 71 insertions(+), 36 deletions(-) > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > index b586b3f..5d16d18 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -1616,7 +1616,6 @@ static u32 tun_do_xdp(struct tun_struct *tun, > switch (act) { > case XDP_REDIRECT: > *err = xdp_do_redirect(tun->dev, xdp, xdp_prog); > - xdp_do_flush_map(); > if (*err) > break; > goto out; > @@ -1624,7 +1623,6 @@ static u32 tun_do_xdp(struct tun_struct *tun, > *err = tun_xdp_tx(tun->dev, xdp); > if (*err) > break; > - tun_xdp_flush(tun->dev); > goto out; > case XDP_PASS: > goto out; > @@ -2400,9 +2398,6 @@ static int tun_xdp_one(struct tun_struct *tun, > int err = 0; > bool skb_xdp = false; > > - preempt_disable(); > - rcu_read_lock(); > - > xdp_prog = rcu_dereference(tun->xdp_prog); > if (xdp_prog) { > if (gso->gso_type) { > @@ -2461,15 +2456,12 @@ static int tun_xdp_one(struct tun_struct *tun, > tun_flow_update(tun, rxhash, tfile); > > out: > - rcu_read_unlock(); > - preempt_enable(); > - > return err; > } > > static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len) > { > - int ret; > + int ret, i; > struct tun_file *tfile = container_of(sock, struct tun_file, socket); > struct tun_struct *tun = tun_get(tfile); > struct tun_msg_ctl *ctl = m->msg_control; > @@ -2477,10 +2469,28 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len) > if (!tun) > return -EBADFD; > > - if (ctl && ctl->type == TUN_MSG_PTR) { > - ret = tun_xdp_one(tun, tfile, ctl->ptr); > - if (!ret) > - ret = total_len; > + if (ctl && ((ctl->type & 0xF) == TUN_MSG_PTR)) { > + int n = ctl->type >> 16; > + > + preempt_disable(); > + rcu_read_lock(); > + > + for (i = 0; i < n; i++) { > + struct xdp_buff *x = (struct xdp_buff *)ctl->ptr; > + struct xdp_buff *xdp = &x[i]; > + > + xdp_set_data_meta_invalid(xdp); > + xdp->rxq = &tfile->xdp_rxq; > + tun_xdp_one(tun, tfile, xdp); > + } > + > + xdp_do_flush_map(); > + tun_xdp_flush(tun->dev); > + > + rcu_read_unlock(); > + preempt_enable(); > + > + ret = total_len; > goto out; > } > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c > index 0d84de6..bec4109 100644 > --- a/drivers/vhost/net.c > +++ b/drivers/vhost/net.c > @@ -118,6 +118,7 @@ struct vhost_net_virtqueue { > struct ptr_ring *rx_ring; > struct vhost_net_buf rxq; > struct xdp_buff xdp[VHOST_RX_BATCH]; > + struct vring_used_elem heads[VHOST_RX_BATCH]; > }; > > struct vhost_net { > @@ -511,7 +512,7 @@ static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq, > void *buf; > int copied; > > - if (len < nvq->sock_hlen) > + if (unlikely(len < nvq->sock_hlen)) > return -EFAULT; > > if (SKB_DATA_ALIGN(len + pad) + > @@ -567,11 +568,37 @@ static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq, > return 0; > } > > +static void vhost_tx_batch(struct vhost_net *net, > + struct vhost_net_virtqueue *nvq, > + struct socket *sock, > + struct msghdr *msghdr, int n) > +{ > + struct tun_msg_ctl ctl = { > + .type = n << 16 | TUN_MSG_PTR, > + .ptr = nvq->xdp, > + }; > + int err; > + > + if (n == 0) > + return; > + > + msghdr->msg_control = &ctl; > + err = sock->ops->sendmsg(sock, msghdr, 0); > + > + if (unlikely(err < 0)) { > + /* FIXME vq_err() */ > + vq_err(&nvq->vq, "sendmsg err!\n"); > + return; > + } > + vhost_add_used_and_signal_n(&net->dev, &nvq->vq, nvq->vq.heads, n); > +} > + > +/* Expects to be always run from workqueue - which acts as > + * read-size critical section for our kind of RCU. */ > static void handle_tx_copy(struct vhost_net *net) > { > struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX]; > struct vhost_virtqueue *vq = &nvq->vq; > - struct xdp_buff xdp; > unsigned out, in; > int head; > struct msghdr msg = { > @@ -586,7 +613,6 @@ static void handle_tx_copy(struct vhost_net *net) > size_t hdr_size; > struct socket *sock; > struct vhost_net_ubuf_ref *uninitialized_var(ubufs); > - struct tun_msg_ctl ctl; > int sent_pkts = 0; > s16 nheads = 0; > > @@ -631,22 +657,24 @@ static void handle_tx_copy(struct vhost_net *net) > vq->heads[nheads].id = cpu_to_vhost32(vq, head); > vq->heads[nheads].len = 0; > > - err = vhost_net_build_xdp(nvq, &msg.msg_iter, &xdp); > - if (!err) { > - ctl.type = TUN_MSG_PTR; > - ctl.ptr = &xdp; > - msg.msg_control = &ctl; > - } else > - msg.msg_control = NULL; > - > total_len += len; > - if (total_len < VHOST_NET_WEIGHT && > - vhost_has_more_pkts(net, vq)) { > - msg.msg_flags |= MSG_MORE; > - } else { > - msg.msg_flags &= ~MSG_MORE; > + err = vhost_net_build_xdp(nvq, &msg.msg_iter, > + &nvq->xdp[nheads]); > + if (!err) { > + if (++nheads == VHOST_RX_BATCH) { > + vhost_tx_batch(net, nvq, sock, &msg, nheads); > + nheads = 0; > + } > + goto done; > + } else if (unlikely(err != -ENOSPC)) { > + vq_err(vq, "Fail to build XDP buffer\n"); > + break; > } > > + vhost_tx_batch(net, nvq, sock, &msg, nheads); > + msg.msg_control = NULL; > + nheads = 0; > + > /* TODO: Check specific error and bomb out unless ENOBUFS? */ > err = sock->ops->sendmsg(sock, &msg, len); > if (unlikely(err < 0)) { > @@ -657,11 +685,9 @@ static void handle_tx_copy(struct vhost_net *net) > if (err != len) > pr_debug("Truncated TX packet: " > " len %d != %zd\n", err, len); > - if (++nheads == VHOST_RX_BATCH) { > - vhost_add_used_and_signal_n(&net->dev, vq, vq->heads, > - nheads); > - nheads = 0; > - } > + > + vhost_add_used_and_signal(&net->dev, vq, head, 0); > +done: > if (vhost_exceeds_weight(++sent_pkts, total_len)) { > vhost_poll_queue(&vq->poll); > break; > @@ -669,8 +695,7 @@ static void handle_tx_copy(struct vhost_net *net) > } > out: > if (nheads) > - vhost_add_used_and_signal_n(&net->dev, vq, vq->heads, > - nheads); > + vhost_tx_batch(net, nvq, sock, &msg, nheads); > mutex_unlock(&vq->mutex); > } > > -- > 2.7.4