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From: "Michael S. Tsirkin" <mst@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Jakub Kicinski <kuba@kernel.org>,
	Jason Wang <jasowang@redhat.com>, Wei Wang <weiwan@google.com>,
	David Miller <davem@davemloft.net>,
	netdev@vger.kernel.org, Willem de Bruijn <willemb@google.com>,
	virtualization@lists.linux-foundation.org
Subject: [PATCH RFC v2 2/4] virtio_net: disable cb aggressively
Date: Tue, 13 Apr 2021 01:47:49 -0400	[thread overview]
Message-ID: <20210413054733.36363-3-mst@redhat.com> (raw)
In-Reply-To: <20210413054733.36363-1-mst@redhat.com>

There are currently two cases where we poll TX vq not in response to a
callback: start xmit and rx napi.  We currently do this with callbacks
enabled which can cause extra interrupts from the card.  Used not to be
a big issue as we run with interrupts disabled but that is no longer the
case, and in some cases the rate of spurious interrupts is so high
linux detects this and actually kills the interrupt.

Fix up by disabling the callbacks before polling the tx vq.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/net/virtio_net.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 82e520d2cb12..16d5abed582c 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1429,6 +1429,7 @@ static void virtnet_poll_cleantx(struct receive_queue *rq)
 		return;
 
 	if (__netif_tx_trylock(txq)) {
+		virtqueue_disable_cb(sq->vq);
 		free_old_xmit_skbs(sq, true);
 		__netif_tx_unlock(txq);
 	}
@@ -1582,6 +1583,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
 	bool use_napi = sq->napi.weight;
 
 	/* Free up any pending old buffers before queueing new ones. */
+	virtqueue_disable_cb(sq->vq);
 	free_old_xmit_skbs(sq, false);
 
 	if (use_napi && kick)
-- 
MST


WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Willem de Bruijn <willemb@google.com>,
	netdev@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	Jakub Kicinski <kuba@kernel.org>, Wei Wang <weiwan@google.com>,
	David Miller <davem@davemloft.net>
Subject: [PATCH RFC v2 2/4] virtio_net: disable cb aggressively
Date: Tue, 13 Apr 2021 01:47:49 -0400	[thread overview]
Message-ID: <20210413054733.36363-3-mst@redhat.com> (raw)
In-Reply-To: <20210413054733.36363-1-mst@redhat.com>

There are currently two cases where we poll TX vq not in response to a
callback: start xmit and rx napi.  We currently do this with callbacks
enabled which can cause extra interrupts from the card.  Used not to be
a big issue as we run with interrupts disabled but that is no longer the
case, and in some cases the rate of spurious interrupts is so high
linux detects this and actually kills the interrupt.

Fix up by disabling the callbacks before polling the tx vq.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/net/virtio_net.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 82e520d2cb12..16d5abed582c 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1429,6 +1429,7 @@ static void virtnet_poll_cleantx(struct receive_queue *rq)
 		return;
 
 	if (__netif_tx_trylock(txq)) {
+		virtqueue_disable_cb(sq->vq);
 		free_old_xmit_skbs(sq, true);
 		__netif_tx_unlock(txq);
 	}
@@ -1582,6 +1583,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
 	bool use_napi = sq->napi.weight;
 
 	/* Free up any pending old buffers before queueing new ones. */
+	virtqueue_disable_cb(sq->vq);
 	free_old_xmit_skbs(sq, false);
 
 	if (use_napi && kick)
-- 
MST

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Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

  parent reply	other threads:[~2021-04-13  5:48 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-13  5:47 [PATCH RFC v2 0/4] virtio net: spurious interrupt related fixes Michael S. Tsirkin
2021-04-13  5:47 ` Michael S. Tsirkin
2021-04-13  5:47 ` [PATCH RFC v2 1/4] virtio: fix up virtio_disable_cb Michael S. Tsirkin
2021-04-13  5:47   ` Michael S. Tsirkin
2021-04-13  8:51   ` Jason Wang
2021-04-13  8:51     ` Jason Wang
2021-04-13 14:01   ` Willem de Bruijn
2021-04-13 14:01     ` Willem de Bruijn
2021-04-13 19:53     ` Michael S. Tsirkin
2021-04-13 19:53       ` Michael S. Tsirkin
2021-04-13 21:44       ` Willem de Bruijn
2021-04-13 21:44         ` Willem de Bruijn
2021-04-13 22:11         ` Michael S. Tsirkin
2021-04-13 22:11           ` Michael S. Tsirkin
2021-04-14  0:24           ` Willem de Bruijn
2021-04-14  0:24             ` Willem de Bruijn
2021-04-13  5:47 ` Michael S. Tsirkin [this message]
2021-04-13  5:47   ` [PATCH RFC v2 2/4] virtio_net: disable cb aggressively Michael S. Tsirkin
2021-04-13  8:53   ` Jason Wang
2021-04-13  8:53     ` Jason Wang
2021-04-13 14:08     ` Willem de Bruijn
2021-04-13 14:08       ` Willem de Bruijn
2021-04-13 14:33     ` Michael S. Tsirkin
2021-04-13 14:33       ` Michael S. Tsirkin
2021-04-13  5:47 ` [PATCH RFC v2 3/4] virtio_net: move tx vq operation under tx queue lock Michael S. Tsirkin
2021-04-13  5:47   ` Michael S. Tsirkin
2021-04-13  8:54   ` Jason Wang
2021-04-13  8:54     ` Jason Wang
2021-04-13 14:02     ` Michael S. Tsirkin
2021-04-13 14:02       ` Michael S. Tsirkin
2021-04-13 14:20       ` Willem de Bruijn
2021-04-13 14:20         ` Willem de Bruijn
2021-04-13 19:38         ` Michael S. Tsirkin
2021-04-13 19:38           ` Michael S. Tsirkin
2021-04-13  5:47 ` [PATCH RFC v2 4/4] virtio_net: move txq wakeups under tx q lock Michael S. Tsirkin
2021-04-13  5:47   ` Michael S. Tsirkin

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