From mboxrd@z Thu Jan 1 00:00:00 1970 From: Willem de Bruijn Subject: [PATCH net-next RFC 4/4] virtio-net: clean tx descriptors from rx napi Date: Fri, 3 Mar 2017 09:39:09 -0500 Message-ID: <20170303143909.80001-5-willemdebruijn.kernel@gmail.com> References: <20170303143909.80001-1-willemdebruijn.kernel@gmail.com> Cc: jasowang@redhat.com, mst@redhat.com, Willem de Bruijn To: netdev@vger.kernel.org Return-path: Received: from mail-qk0-f196.google.com ([209.85.220.196]:33605 "EHLO mail-qk0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752236AbdCCOrr (ORCPT ); Fri, 3 Mar 2017 09:47:47 -0500 Received: by mail-qk0-f196.google.com with SMTP id j127so9425588qke.0 for ; Fri, 03 Mar 2017 06:47:46 -0800 (PST) In-Reply-To: <20170303143909.80001-1-willemdebruijn.kernel@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Willem de Bruijn Amortize the cost of virtual interrupts by doing both rx and tx work on reception of a receive interrupt. Together VIRTIO_F_EVENT_IDX and vhost interrupt moderation, this suppresses most explicit tx completion interrupts for bidirectional workloads. Signed-off-by: Willem de Bruijn --- drivers/net/virtio_net.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 9a9031640179..21c575127d50 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1031,6 +1031,23 @@ static int virtnet_receive(struct receive_queue *rq, int budget) return received; } +static unsigned int free_old_xmit_skbs(struct send_queue *sq, int budget); + +static void virtnet_poll_cleantx(struct receive_queue *rq) +{ + struct virtnet_info *vi = rq->vq->vdev->priv; + unsigned int index = vq2rxq(rq->vq); + struct send_queue *sq = &vi->sq[index]; + struct netdev_queue *txq = netdev_get_tx_queue(vi->dev, index); + + __netif_tx_lock(txq, smp_processor_id()); + free_old_xmit_skbs(sq, sq->napi.weight); + __netif_tx_unlock(txq); + + if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) + netif_wake_subqueue(vi->dev, vq2txq(sq->vq)); +} + static int virtnet_poll(struct napi_struct *napi, int budget) { struct receive_queue *rq = @@ -1039,6 +1056,8 @@ static int virtnet_poll(struct napi_struct *napi, int budget) received = virtnet_receive(rq, budget); + virtnet_poll_cleantx(rq); + /* Out of packets? */ if (received < budget) virtqueue_napi_complete(napi, rq->vq, received); -- 2.12.0.rc1.440.g5b76565f74-goog