From 70181d51209cbcdf9ce2171eac3f3458281d2947 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Wed, 10 Apr 2013 20:50:48 +0000 Subject: [PATCH] vhost_net: remove tx polling state After commit 2b8b328b61c799957a456a5a8dab8cc7dea68575 (vhost_net: handle polling errors when setting backend), we in fact track the polling state through poll->wqh, so there's no need to duplicate the work with an extra vhost_net_polling_state. So this patch removes this and make the code simpler. This patch also removes the all tx starting/stopping code in tx path according to Michael's suggestion. Netperf test shows almost the same result in stream test, but gets improvements on TCP_RR tests (both zerocopy or copy) especially on low load cases. Tested between multiqueue kvm guest and external host with two direct connected 82599s. zerocopy disabled: sessions|transaction rates|normalize| before/after/+improvements 1 | 9510.24/11727.29/+23.3% | 693.54/887.68/+28.0% | 25| 192931.50/241729.87/+25.3% | 2376.80/2771.70/+16.6% | 50| 277634.64/291905.76/+5% | 3118.36/3230.11/+3.6% | zerocopy enabled: sessions|transaction rates|normalize| before/after/+improvements 1 | 7318.33/11929.76/+63.0% | 521.86/843.30/+61.6% | 25| 167264.88/242422.15/+44.9% | 2181.60/2788.16/+27.8% | 50| 272181.02/294347.04/+8.1% | 3071.56/3257.85/+6.1% | Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller --- drivers/vhost/net.c | 74 ++++--------------------------------------- drivers/vhost/vhost.c | 3 ++ 2 files changed, 9 insertions(+), 68 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index ec6fb3fa59bb..87c216c1e54e 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -64,20 +64,10 @@ enum { VHOST_NET_VQ_MAX = 2, }; -enum vhost_net_poll_state { - VHOST_NET_POLL_DISABLED = 0, - VHOST_NET_POLL_STARTED = 1, - VHOST_NET_POLL_STOPPED = 2, -}; - struct vhost_net { struct vhost_dev dev; struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX]; struct vhost_poll poll[VHOST_NET_VQ_MAX]; - /* Tells us whether we are polling a socket for TX. - * We only do this when socket buffer fills up. - * Protected by tx vq lock. */ - enum vhost_net_poll_state tx_poll_state; /* Number of TX recently submitted. * Protected by tx vq lock. */ unsigned tx_packets; @@ -155,28 +145,6 @@ static void copy_iovec_hdr(const struct iovec *from, struct iovec *to, } } -/* Caller must have TX VQ lock */ -static void tx_poll_stop(struct vhost_net *net) -{ - if (likely(net->tx_poll_state != VHOST_NET_POLL_STARTED)) - return; - vhost_poll_stop(net->poll + VHOST_NET_VQ_TX); - net->tx_poll_state = VHOST_NET_POLL_STOPPED; -} - -/* Caller must have TX VQ lock */ -static int tx_poll_start(struct vhost_net *net, struct socket *sock) -{ - int ret; - - if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED)) - return 0; - ret = vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file); - if (!ret) - net->tx_poll_state = VHOST_NET_POLL_STARTED; - return ret; -} - /* In case of DMA done not in order in lower device driver for some reason. * upend_idx is used to track end of used idx, done_idx is used to track head * of used idx. Once lower device DMA done contiguously, we will signal KVM @@ -242,7 +210,7 @@ static void handle_tx(struct vhost_net *net) .msg_flags = MSG_DONTWAIT, }; size_t len, total_len = 0; - int err, wmem; + int err; size_t hdr_size; struct socket *sock; struct vhost_ubuf_ref *uninitialized_var(ubufs); @@ -253,19 +221,9 @@ static void handle_tx(struct vhost_net *net) if (!sock) return; - wmem = atomic_read(&sock->sk->sk_wmem_alloc); - if (wmem >= sock->sk->sk_sndbuf) { - mutex_lock(&vq->mutex); - tx_poll_start(net, sock); - mutex_unlock(&vq->mutex); - return; - } - mutex_lock(&vq->mutex); vhost_disable_notify(&net->dev, vq); - if (wmem < sock->sk->sk_sndbuf / 2) - tx_poll_stop(net); hdr_size = vq->vhost_hlen; zcopy = vq->ubufs; @@ -285,23 +243,14 @@ static void handle_tx(struct vhost_net *net) if (head == vq->num) { int num_pends; - wmem = atomic_read(&sock->sk->sk_wmem_alloc); - if (wmem >= sock->sk->sk_sndbuf * 3 / 4) { - tx_poll_start(net, sock); - set_bit(SOCK_ASYNC_NOSPACE, &sock->flags); - break; - } /* If more outstanding DMAs, queue the work. * Handle upend_idx wrap around */ num_pends = likely(vq->upend_idx >= vq->done_idx) ? (vq->upend_idx - vq->done_idx) : (vq->upend_idx + UIO_MAXIOV - vq->done_idx); - if (unlikely(num_pends > VHOST_MAX_PEND)) { - tx_poll_start(net, sock); - set_bit(SOCK_ASYNC_NOSPACE, &sock->flags); + if (unlikely(num_pends > VHOST_MAX_PEND)) break; - } if (unlikely(vhost_enable_notify(&net->dev, vq))) { vhost_disable_notify(&net->dev, vq); continue; @@ -364,8 +313,6 @@ static void handle_tx(struct vhost_net *net) UIO_MAXIOV; } vhost_discard_vq_desc(vq, 1); - if (err == -EAGAIN || err == -ENOBUFS) - tx_poll_start(net, sock); break; } if (err != len) @@ -628,7 +575,6 @@ static int vhost_net_open(struct inode *inode, struct file *f) vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev); vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev); - n->tx_poll_state = VHOST_NET_POLL_DISABLED; f->private_data = n; @@ -638,32 +584,24 @@ static int vhost_net_open(struct inode *inode, struct file *f) static void vhost_net_disable_vq(struct vhost_net *n, struct vhost_virtqueue *vq) { + struct vhost_poll *poll = n->poll + (vq - n->vqs); if (!vq->private_data) return; - if (vq == n->vqs + VHOST_NET_VQ_TX) { - tx_poll_stop(n); - n->tx_poll_state = VHOST_NET_POLL_DISABLED; - } else - vhost_poll_stop(n->poll + VHOST_NET_VQ_RX); + vhost_poll_stop(poll); } static int vhost_net_enable_vq(struct vhost_net *n, struct vhost_virtqueue *vq) { + struct vhost_poll *poll = n->poll + (vq - n->vqs); struct socket *sock; - int ret; sock = rcu_dereference_protected(vq->private_data, lockdep_is_held(&vq->mutex)); if (!sock) return 0; - if (vq == n->vqs + VHOST_NET_VQ_TX) { - n->tx_poll_state = VHOST_NET_POLL_STOPPED; - ret = tx_poll_start(n, sock); - } else - ret = vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file); - return ret; + return vhost_poll_start(poll, sock->file); } static struct socket *vhost_net_stop_vq(struct vhost_net *n, diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 9759249e6d90..4eecdb867d53 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -89,6 +89,9 @@ int vhost_poll_start(struct vhost_poll *poll, struct file *file) unsigned long mask; int ret = 0; + if (poll->wqh) + return 0; + mask = file->f_op->poll(file, &poll->table); if (mask) vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);