From: Daniel Borkmann <daniel@iogearbox•net>
To: John Fastabend <john.fastabend@gmail•com>,
eric.dumazet@gmail•com, mst@redhat•com, kubakici@wp•pl,
shm@cumulusnetworks•com, davem@davemloft•net,
alexei.starovoitov@gmail•com
Cc: netdev@vger•kernel.org, bblanco@plumgrid•com,
john.r.fastabend@intel•com, brouer@redhat•com, tgraf@suug•ch
Subject: Re: [net-next PATCH v2 4/5] virtio_net: add dedicated XDP transmit queues
Date: Mon, 21 Nov 2016 12:45:36 +0100 [thread overview]
Message-ID: <5832DE60.4000200@iogearbox.net> (raw)
In-Reply-To: <20161120025104.19187.54400.stgit@john-Precision-Tower-5810>
On 11/20/2016 03:51 AM, John Fastabend wrote:
> XDP requires using isolated transmit queues to avoid interference
> with normal networking stack (BQL, NETDEV_TX_BUSY, etc). This patch
> adds a XDP queue per cpu when a XDP program is loaded and does not
> expose the queues to the OS via the normal API call to
> netif_set_real_num_tx_queues(). This way the stack will never push
> an skb to these queues.
>
> However virtio/vhost/qemu implementation only allows for creating
> TX/RX queue pairs at this time so creating only TX queues was not
> possible. And because the associated RX queues are being created I
> went ahead and exposed these to the stack and let the backend use
> them. This creates more RX queues visible to the network stack than
> TX queues which is worth mentioning but does not cause any issues as
> far as I can tell.
>
> Signed-off-by: John Fastabend <john.r.fastabend@intel•com>
> ---
> drivers/net/virtio_net.c | 32 +++++++++++++++++++++++++++++---
> 1 file changed, 29 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 8f99a53..80a426c 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -114,6 +114,9 @@ struct virtnet_info {
> /* # of queue pairs currently used by the driver */
> u16 curr_queue_pairs;
>
> + /* # of XDP queue pairs currently used by the driver */
> + u16 xdp_queue_pairs;
> +
> /* I like... big packets and I cannot lie! */
> bool big_packets;
>
> @@ -1525,7 +1528,8 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
> {
> struct virtnet_info *vi = netdev_priv(dev);
> struct bpf_prog *old_prog;
> - int i;
> + u16 xdp_qp = 0, curr_qp;
> + int err, i;
>
> if ((dev->features & NETIF_F_LRO) && prog) {
> netdev_warn(dev, "can't set XDP while LRO is on, disable LRO first\n");
> @@ -1542,12 +1546,34 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
> return -EINVAL;
> }
>
> + curr_qp = vi->curr_queue_pairs - vi->xdp_queue_pairs;
> + if (prog)
> + xdp_qp = nr_cpu_ids;
> +
> + /* XDP requires extra queues for XDP_TX */
> + if (curr_qp + xdp_qp > vi->max_queue_pairs) {
> + netdev_warn(dev, "request %i queues but max is %i\n",
> + curr_qp + xdp_qp, vi->max_queue_pairs);
> + return -ENOMEM;
> + }
> +
> + err = virtnet_set_queues(vi, curr_qp + xdp_qp);
> + if (err) {
> + dev_warn(&dev->dev, "XDP Device queue allocation failure.\n");
> + return err;
> + }
> +
> if (prog) {
> - prog = bpf_prog_add(prog, vi->max_queue_pairs - 1);
> - if (IS_ERR(prog))
> + prog = bpf_prog_add(prog, vi->max_queue_pairs);
I think this change is not correct, it would be off by one now.
The previous 'vi->max_queue_pairs - 1' was actually correct here.
dev_change_xdp_fd() already gives you a reference (see the doc on
enum xdp_netdev_command in netdevice.h).
> + if (IS_ERR(prog)) {
> + virtnet_set_queues(vi, curr_qp);
> return PTR_ERR(prog);
> + }
> }
>
> + vi->xdp_queue_pairs = xdp_qp;
> + netif_set_real_num_rx_queues(dev, curr_qp + xdp_qp);
> +
> for (i = 0; i < vi->max_queue_pairs; i++) {
> old_prog = rtnl_dereference(vi->rq[i].xdp_prog);
> rcu_assign_pointer(vi->rq[i].xdp_prog, prog);
>
next prev parent reply other threads:[~2016-11-21 11:45 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-20 2:49 [net-next PATCH v2 0/5] XDP for virtio_net John Fastabend
2016-11-20 2:49 ` [net-next PATCH v2 1/5] net: virtio dynamically disable/enable LRO John Fastabend
2016-11-21 23:23 ` Michael S. Tsirkin
2016-11-22 8:16 ` John Fastabend
2016-11-20 2:50 ` [net-next PATCH v2 2/5] net: xdp: add invalid buffer warning John Fastabend
2016-11-20 2:50 ` [net-next PATCH v2 3/5] virtio_net: Add XDP support John Fastabend
2016-11-21 23:20 ` Michael S. Tsirkin
2016-11-22 8:27 ` John Fastabend
2016-11-22 14:58 ` Michael S. Tsirkin
2016-11-25 21:24 ` John Fastabend
2016-11-28 3:36 ` Michael S. Tsirkin
2016-11-28 3:56 ` John Fastabend
2016-11-28 4:07 ` Michael S. Tsirkin
2016-11-28 23:26 ` John Fastabend
2016-11-20 2:51 ` [net-next PATCH v2 4/5] virtio_net: add dedicated XDP transmit queues John Fastabend
2016-11-21 11:45 ` Daniel Borkmann [this message]
2016-11-21 15:56 ` John Fastabend
2016-11-21 23:13 ` Michael S. Tsirkin
2016-11-22 8:17 ` John Fastabend
2016-11-22 14:59 ` Michael S. Tsirkin
2016-11-20 2:51 ` [net-next PATCH v2 5/5] virtio_net: add XDP_TX support John Fastabend
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5832DE60.4000200@iogearbox.net \
--to=daniel@iogearbox$(echo .)net \
--cc=alexei.starovoitov@gmail$(echo .)com \
--cc=bblanco@plumgrid$(echo .)com \
--cc=brouer@redhat$(echo .)com \
--cc=davem@davemloft$(echo .)net \
--cc=eric.dumazet@gmail$(echo .)com \
--cc=john.fastabend@gmail$(echo .)com \
--cc=john.r.fastabend@intel$(echo .)com \
--cc=kubakici@wp$(echo .)pl \
--cc=mst@redhat$(echo .)com \
--cc=netdev@vger$(echo .)kernel.org \
--cc=shm@cumulusnetworks$(echo .)com \
--cc=tgraf@suug$(echo .)ch \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox