From 61845d2072150e896f2f18f1d879956e453ee8fd Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Fri, 17 Feb 2017 11:33:09 +0800 Subject: [PATCH] virtio-net: batch stats updating We already have counters for sent/recv packets and sent/recv bytes. Doing a batched update to reduce the number of u64_stats_update_begin/end(). Take care not to bother with stats update when called speculatively. Cc: Willem de Bruijn Signed-off-by: Jason Wang Signed-off-by: Michael S. Tsirkin Signed-off-by: David S. Miller --- drivers/net/virtio_net.c | 47 ++++++++++++++++++++++++++-------------- 1 file changed, 31 insertions(+), 16 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 11e28530c83c..05a83dbc910d 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -719,13 +719,13 @@ xdp_xmit: return NULL; } -static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq, - void *buf, unsigned int len) +static int receive_buf(struct virtnet_info *vi, struct receive_queue *rq, + void *buf, unsigned int len) { struct net_device *dev = vi->dev; - struct virtnet_stats *stats = this_cpu_ptr(vi->stats); struct sk_buff *skb; struct virtio_net_hdr_mrg_rxbuf *hdr; + int ret; if (unlikely(len < vi->hdr_len + ETH_HLEN)) { pr_debug("%s: short packet %i\n", dev->name, len); @@ -739,7 +739,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq, } else { dev_kfree_skb(buf); } - return; + return 0; } if (vi->mergeable_rx_bufs) @@ -750,14 +750,11 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq, skb = receive_small(dev, vi, rq, buf, len); if (unlikely(!skb)) - return; + return 0; hdr = skb_vnet_hdr(skb); - u64_stats_update_begin(&stats->rx_syncp); - stats->rx_bytes += skb->len; - stats->rx_packets++; - u64_stats_update_end(&stats->rx_syncp); + ret = skb->len; if (hdr->hdr.flags & VIRTIO_NET_HDR_F_DATA_VALID) skb->ip_summed = CHECKSUM_UNNECESSARY; @@ -775,11 +772,12 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq, ntohs(skb->protocol), skb->len, skb->pkt_type); napi_gro_receive(&rq->napi, skb); - return; + return ret; frame_err: dev->stats.rx_frame_errors++; dev_kfree_skb(skb); + return 0; } static unsigned int virtnet_get_headroom(struct virtnet_info *vi) @@ -994,12 +992,13 @@ static void refill_work(struct work_struct *work) static int virtnet_receive(struct receive_queue *rq, int budget) { struct virtnet_info *vi = rq->vq->vdev->priv; - unsigned int len, received = 0; + unsigned int len, received = 0, bytes = 0; void *buf; + struct virtnet_stats *stats = this_cpu_ptr(vi->stats); while (received < budget && (buf = virtqueue_get_buf(rq->vq, &len)) != NULL) { - receive_buf(vi, rq, buf, len); + bytes += receive_buf(vi, rq, buf, len); received++; } @@ -1008,6 +1007,11 @@ static int virtnet_receive(struct receive_queue *rq, int budget) schedule_delayed_work(&vi->refill, 0); } + u64_stats_update_begin(&stats->rx_syncp); + stats->rx_bytes += bytes; + stats->rx_packets += received; + u64_stats_update_end(&stats->rx_syncp); + return received; } @@ -1056,17 +1060,28 @@ static void free_old_xmit_skbs(struct send_queue *sq) unsigned int len; struct virtnet_info *vi = sq->vq->vdev->priv; struct virtnet_stats *stats = this_cpu_ptr(vi->stats); + unsigned int packets = 0; + unsigned int bytes = 0; while ((skb = virtqueue_get_buf(sq->vq, &len)) != NULL) { pr_debug("Sent skb %p\n", skb); - u64_stats_update_begin(&stats->tx_syncp); - stats->tx_bytes += skb->len; - stats->tx_packets++; - u64_stats_update_end(&stats->tx_syncp); + bytes += skb->len; + packets++; dev_kfree_skb_any(skb); } + + /* Avoid overhead when no packets have been processed + * happens when called speculatively from start_xmit. + */ + if (!packets) + return; + + u64_stats_update_begin(&stats->tx_syncp); + stats->tx_bytes += bytes; + stats->tx_packets += packets; + u64_stats_update_end(&stats->tx_syncp); } static int xmit_skb(struct send_queue *sq, struct sk_buff *skb) -- 2.39.2