From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: Koichiro Den <den@klaipeden.com>
Cc: Network Development <netdev@vger.kernel.org>,
virtualization@lists.linux-foundation.org,
"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH net-next] virtio-net: invoke zerocopy callback on xmit path if no tx napi
Date: Sun, 20 Aug 2017 16:49:15 -0400 [thread overview]
Message-ID: <CAF=yD-LYLsQNt_5yYZ+PUwv04ZwaJUXn-YakH=tuh0TV+BG7iA@mail.gmail.com> (raw)
In-Reply-To: <20170819063854.27010-1-den@klaipeden.com>
On Sat, Aug 19, 2017 at 2:38 AM, Koichiro Den <den@klaipeden.com> wrote:
> Facing the possible unbounded delay relying on freeing on xmit path,
> we also better to invoke and clear the upper layer zerocopy callback
> beforehand to keep them from waiting for unbounded duration in vain.
Good point.
> For instance, this removes the possible deadlock in the case that the
> upper layer is a zerocopy-enabled vhost-net.
> This does not apply if napi_tx is enabled since it will be called in
> reasonale time.
Indeed. Btw, I am gathering data to eventually make napi the default
mode. But that is taking some time.
>
> Signed-off-by: Koichiro Den <den@klaipeden.com>
> ---
> drivers/net/virtio_net.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 4302f313d9a7..f7deaa5b7b50 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1290,6 +1290,14 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
>
> /* Don't wait up for transmitted skbs to be freed. */
> if (!use_napi) {
> + if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
> + struct ubuf_info *uarg;
> + uarg = skb_shinfo(skb)->destructor_arg;
> + if (uarg->callback)
> + uarg->callback(uarg, true);
> + skb_shinfo(skb)->destructor_arg = NULL;
> + skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;
> + }
Instead of open coding, this can use skb_zcopy_clear.
> skb_orphan(skb);
> nf_reset(skb);
> }
> --
> 2.9.4
>
>
next prev parent reply other threads:[~2017-08-20 20:49 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-19 6:38 [PATCH net-next] virtio-net: invoke zerocopy callback on xmit path if no tx napi Koichiro Den
2017-08-20 20:49 ` Willem de Bruijn [this message]
2017-08-21 12:40 ` Koichiro Den
2017-08-22 12:11 ` Willem de Bruijn
2017-08-22 14:04 ` Koichiro Den
2017-08-22 17:19 ` Willem de Bruijn
2017-08-23 14:26 ` Koichiro Den
2017-08-21 12:33 ` Jason Wang
2017-08-21 12:58 ` Koichiro Den
2017-08-21 15:41 ` Willem de Bruijn
2017-08-22 2:50 ` Jason Wang
2017-08-22 3:10 ` Willem de Bruijn
2017-08-22 11:47 ` Jason Wang
2017-08-22 13:42 ` Koichiro Den
2017-08-22 17:16 ` Willem de Bruijn
2017-08-23 14:24 ` Koichiro Den
2017-08-22 17:55 ` Michael S. Tsirkin
2017-08-22 18:01 ` David Miller
2017-08-22 18:28 ` Eric Dumazet
2017-08-22 18:39 ` Michael S. Tsirkin
2017-08-23 14:28 ` Koichiro Den
2017-08-23 14:47 ` Koichiro Den
2017-08-23 15:20 ` Willem de Bruijn
2017-08-23 22:57 ` Michael S. Tsirkin
2017-08-24 3:28 ` Willem de Bruijn
2017-08-24 4:34 ` Michael S. Tsirkin
2017-08-24 13:50 ` Michael S. Tsirkin
2017-08-24 20:20 ` Willem de Bruijn
2017-08-24 20:50 ` Michael S. Tsirkin
2017-08-25 22:44 ` Willem de Bruijn
2017-08-25 23:32 ` Michael S. Tsirkin
2017-08-26 1:03 ` Willem de Bruijn
2017-08-29 19:35 ` Willem de Bruijn
2017-08-29 19:42 ` Michael S. Tsirkin
2017-08-29 19:53 ` Willem de Bruijn
2017-08-29 20:40 ` Michael S. Tsirkin
2017-08-29 22:55 ` Willem de Bruijn
2017-08-30 1:45 ` Jason Wang
2017-08-30 3:11 ` Willem de Bruijn
2017-09-01 3:08 ` Jason Wang
2017-08-31 14:30 ` Willem de Bruijn
2017-09-01 3:25 ` Jason Wang
2017-09-01 16:15 ` Willem de Bruijn
2017-09-01 16:17 ` Willem de Bruijn
2017-09-04 3:03 ` Jason Wang
2017-09-05 14:09 ` Willem de Bruijn
2017-09-06 3:27 ` Michael S. Tsirkin
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