Messages in this thread Patch in this message | | | From | Jason Wang <> | Subject | [RFC V7 PATCH 3/7] virtio-net: optimize free_old_xmit_skbs stats | Date | Mon, 25 May 2015 01:24:00 -0400 |
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We already have counters for sent packets and sent bytes. Use them to reduce the number of u64_stats_update_begin/end().
Take care not to bother with stats update when called speculatively.
Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- drivers/net/virtio_net.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 63c7810..744f0b1 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -826,17 +826,27 @@ 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, 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) -- 1.8.3.1
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