From: "Michael S. Tsirkin" <mst@redhat.com> To: Jason Wang <jasowang@redhat.com> Cc: linux-kernel@vger.kernel.org, Jakub Kicinski <kuba@kernel.org>, 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: Re: [PATCH RFC v2 2/4] virtio_net: disable cb aggressively Date: Tue, 13 Apr 2021 10:33:36 -0400 [thread overview] Message-ID: <20210413100314-mutt-send-email-mst@kernel.org> (raw) In-Reply-To: <43db5c1e-9908-55bb-6d1a-c6c8d71e2315@redhat.com> On Tue, Apr 13, 2021 at 04:53:32PM +0800, Jason Wang wrote: > > 在 2021/4/13 下午1:47, Michael S. Tsirkin 写道: > > 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); > > > Any reason that we don't need to enable the cb here? Good point ... probably only if the vq isn't empty ... > And as we discussed in the past, it's probably the time to have a single > NAPI for both tx and rx? > > Thanks Donnu. I'd like to get a minimal bugfix in, refactoring on top ... > > > } > > @@ -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)
WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com> To: Jason Wang <jasowang@redhat.com> Cc: Willem de Bruijn <willemb@google.com>, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Jakub Kicinski <kuba@kernel.org>, Wei Wang <weiwan@google.com>, David Miller <davem@davemloft.net> Subject: Re: [PATCH RFC v2 2/4] virtio_net: disable cb aggressively Date: Tue, 13 Apr 2021 10:33:36 -0400 [thread overview] Message-ID: <20210413100314-mutt-send-email-mst@kernel.org> (raw) In-Reply-To: <43db5c1e-9908-55bb-6d1a-c6c8d71e2315@redhat.com> On Tue, Apr 13, 2021 at 04:53:32PM +0800, Jason Wang wrote: > > 在 2021/4/13 下午1:47, Michael S. Tsirkin 写道: > > 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); > > > Any reason that we don't need to enable the cb here? Good point ... probably only if the vq isn't empty ... > And as we discussed in the past, it's probably the time to have a single > NAPI for both tx and rx? > > Thanks Donnu. I'd like to get a minimal bugfix in, refactoring on top ... > > > } > > @@ -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) _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
next prev parent reply other threads:[~2021-04-13 14:34 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 ` [PATCH RFC v2 2/4] virtio_net: disable cb aggressively Michael S. Tsirkin 2021-04-13 5:47 ` 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 [this message] 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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