Messages in this thread Patch in this message | | | Date | Mon, 20 Oct 2014 09:52:41 +0300 | From | "Michael S. Tsirkin" <> | Subject | [PATCH RFC v3 3/3] virtio-net: optimize free_old_xmit_skbs stats |
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From: Jason Wang <jasowang@redhat.com>
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.
Based on a patch by Jason Wang.
Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- drivers/net/virtio_net.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index b83d39d..c2b69f8 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -233,16 +233,22 @@ static unsigned int free_old_xmit_skbs(struct netdev_queue *txq, (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; bytes += skb->len; - stats->tx_packets++; - u64_stats_update_end(&stats->tx_syncp); + packets++; dev_kfree_skb_any(skb); - packets++; } + /* Avoid overhead when no packets have been processed + * happens when called speculatively from start_xmit. */ + if (!packets) + return 0; + + u64_stats_update_begin(&stats->tx_syncp); + stats->tx_bytes += bytes; + stats->tx_packets += packets; + u64_stats_update_end(&stats->tx_syncp); + netdev_tx_completed_queue(txq, packets, bytes); if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) -- MST
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