From: "Michael S. Tsirkin" <mst@redhat.com>
To: Stefano Garzarella <sgarzare@redhat.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Stefan Hajnoczi <stefanha@redhat.com>,
"David S. Miller" <davem@davemloft.net>,
virtualization@lists.linux-foundation.org,
Jason Wang <jasowang@redhat.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH v4 4/5] vhost/vsock: split packets to send using multiple buffers
Date: Wed, 17 Jul 2019 10:54:57 -0400 [thread overview]
Message-ID: <20190717105336-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20190717113030.163499-5-sgarzare@redhat.com>
On Wed, Jul 17, 2019 at 01:30:29PM +0200, Stefano Garzarella wrote:
> If the packets to sent to the guest are bigger than the buffer
> available, we can split them, using multiple buffers and fixing
> the length in the packet header.
> This is safe since virtio-vsock supports only stream sockets.
>
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
So how does it work right now? If an app
does sendmsg with a 64K buffer and the other
side publishes 4K buffers - does it just stall?
> ---
> drivers/vhost/vsock.c | 66 ++++++++++++++++++-------
> net/vmw_vsock/virtio_transport_common.c | 15 ++++--
> 2 files changed, 60 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index 6c8390a2af52..9f57736fe15e 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -102,7 +102,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> struct iov_iter iov_iter;
> unsigned out, in;
> size_t nbytes;
> - size_t len;
> + size_t iov_len, payload_len;
> int head;
>
> spin_lock_bh(&vsock->send_pkt_list_lock);
> @@ -147,8 +147,24 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> break;
> }
>
> - len = iov_length(&vq->iov[out], in);
> - iov_iter_init(&iov_iter, READ, &vq->iov[out], in, len);
> + iov_len = iov_length(&vq->iov[out], in);
> + if (iov_len < sizeof(pkt->hdr)) {
> + virtio_transport_free_pkt(pkt);
> + vq_err(vq, "Buffer len [%zu] too small\n", iov_len);
> + break;
> + }
> +
> + iov_iter_init(&iov_iter, READ, &vq->iov[out], in, iov_len);
> + payload_len = pkt->len - pkt->off;
> +
> + /* If the packet is greater than the space available in the
> + * buffer, we split it using multiple buffers.
> + */
> + if (payload_len > iov_len - sizeof(pkt->hdr))
> + payload_len = iov_len - sizeof(pkt->hdr);
> +
> + /* Set the correct length in the header */
> + pkt->hdr.len = cpu_to_le32(payload_len);
>
> nbytes = copy_to_iter(&pkt->hdr, sizeof(pkt->hdr), &iov_iter);
> if (nbytes != sizeof(pkt->hdr)) {
> @@ -157,33 +173,47 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> break;
> }
>
> - nbytes = copy_to_iter(pkt->buf, pkt->len, &iov_iter);
> - if (nbytes != pkt->len) {
> + nbytes = copy_to_iter(pkt->buf + pkt->off, payload_len,
> + &iov_iter);
> + if (nbytes != payload_len) {
> virtio_transport_free_pkt(pkt);
> vq_err(vq, "Faulted on copying pkt buf\n");
> break;
> }
>
> - vhost_add_used(vq, head, sizeof(pkt->hdr) + pkt->len);
> + vhost_add_used(vq, head, sizeof(pkt->hdr) + payload_len);
> added = true;
>
> - if (pkt->reply) {
> - int val;
> -
> - val = atomic_dec_return(&vsock->queued_replies);
> -
> - /* Do we have resources to resume tx processing? */
> - if (val + 1 == tx_vq->num)
> - restart_tx = true;
> - }
> -
> /* Deliver to monitoring devices all correctly transmitted
> * packets.
> */
> virtio_transport_deliver_tap_pkt(pkt);
>
> - total_len += pkt->len;
> - virtio_transport_free_pkt(pkt);
> + pkt->off += payload_len;
> + total_len += payload_len;
> +
> + /* If we didn't send all the payload we can requeue the packet
> + * to send it with the next available buffer.
> + */
> + if (pkt->off < pkt->len) {
> + spin_lock_bh(&vsock->send_pkt_list_lock);
> + list_add(&pkt->list, &vsock->send_pkt_list);
> + spin_unlock_bh(&vsock->send_pkt_list_lock);
> + } else {
> + if (pkt->reply) {
> + int val;
> +
> + val = atomic_dec_return(&vsock->queued_replies);
> +
> + /* Do we have resources to resume tx
> + * processing?
> + */
> + if (val + 1 == tx_vq->num)
> + restart_tx = true;
> + }
> +
> + virtio_transport_free_pkt(pkt);
> + }
> } while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
> if (added)
> vhost_signal(&vsock->dev, vq);
> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> index 34a2b42313b7..56fab3f03d0e 100644
> --- a/net/vmw_vsock/virtio_transport_common.c
> +++ b/net/vmw_vsock/virtio_transport_common.c
> @@ -97,8 +97,17 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
> struct virtio_vsock_pkt *pkt = opaque;
> struct af_vsockmon_hdr *hdr;
> struct sk_buff *skb;
> + size_t payload_len;
> + void *payload_buf;
>
> - skb = alloc_skb(sizeof(*hdr) + sizeof(pkt->hdr) + pkt->len,
> + /* A packet could be split to fit the RX buffer, so we can retrieve
> + * the payload length from the header and the buffer pointer taking
> + * care of the offset in the original packet.
> + */
> + payload_len = le32_to_cpu(pkt->hdr.len);
> + payload_buf = pkt->buf + pkt->off;
> +
> + skb = alloc_skb(sizeof(*hdr) + sizeof(pkt->hdr) + payload_len,
> GFP_ATOMIC);
> if (!skb)
> return NULL;
> @@ -138,8 +147,8 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
>
> skb_put_data(skb, &pkt->hdr, sizeof(pkt->hdr));
>
> - if (pkt->len) {
> - skb_put_data(skb, pkt->buf, pkt->len);
> + if (payload_len) {
> + skb_put_data(skb, payload_buf, payload_len);
> }
>
> return skb;
> --
> 2.20.1
next prev parent reply other threads:[~2019-07-17 14:55 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-17 11:30 [PATCH v4 0/5] vsock/virtio: optimizations to increase the throughput Stefano Garzarella
2019-07-17 11:30 ` [PATCH v4 1/5] vsock/virtio: limit the memory used per-socket Stefano Garzarella
2019-07-29 14:04 ` Michael S. Tsirkin
2019-07-29 15:36 ` Stefano Garzarella
2019-07-29 15:49 ` Michael S. Tsirkin
2019-07-29 16:19 ` Stefano Garzarella
2019-07-29 16:50 ` Stefano Garzarella
2019-07-29 19:10 ` Michael S. Tsirkin
2019-07-30 9:35 ` Stefano Garzarella
2019-07-30 20:42 ` Michael S. Tsirkin
2019-08-01 10:47 ` Stefano Garzarella
2019-08-01 13:21 ` Michael S. Tsirkin
2019-08-01 13:36 ` Stefano Garzarella
2019-09-01 8:26 ` Michael S. Tsirkin
2019-09-01 10:17 ` Michael S. Tsirkin
2019-09-02 9:57 ` Stefano Garzarella
2019-09-02 15:23 ` Michael S. Tsirkin
2019-09-03 4:39 ` Michael S. Tsirkin
2019-09-03 7:45 ` Stefano Garzarella
2019-09-03 7:52 ` Michael S. Tsirkin
2019-09-03 8:00 ` Stefano Garzarella
2019-07-29 16:01 ` Michael S. Tsirkin
2019-07-29 16:41 ` Stefano Garzarella
2019-07-29 19:33 ` Michael S. Tsirkin
2019-08-30 9:40 ` Stefano Garzarella
2019-09-01 6:56 ` Michael S. Tsirkin
2019-09-02 8:39 ` Stefan Hajnoczi
2019-09-02 8:55 ` Stefano Garzarella
2019-10-11 13:40 ` Stefano Garzarella
2019-10-11 14:11 ` Michael S. Tsirkin
2019-10-11 14:23 ` Stefano Garzarella
2019-10-14 8:17 ` Stefan Hajnoczi
2019-10-14 8:21 ` Jason Wang
2019-10-14 8:38 ` Stefano Garzarella
2019-07-17 11:30 ` [PATCH v4 2/5] vsock/virtio: reduce credit update messages Stefano Garzarella
2019-07-22 8:36 ` Stefan Hajnoczi
2019-09-03 4:38 ` Michael S. Tsirkin
2019-09-03 7:31 ` Stefano Garzarella
2019-09-03 7:38 ` Michael S. Tsirkin
2019-07-17 11:30 ` [PATCH v4 3/5] vsock/virtio: fix locking in virtio_transport_inc_tx_pkt() Stefano Garzarella
2019-07-17 14:51 ` Michael S. Tsirkin
2019-07-18 7:43 ` Stefano Garzarella
2019-07-22 8:53 ` Stefan Hajnoczi
2019-07-17 11:30 ` [PATCH v4 4/5] vhost/vsock: split packets to send using multiple buffers Stefano Garzarella
2019-07-17 14:54 ` Michael S. Tsirkin [this message]
2019-07-18 7:50 ` Stefano Garzarella
2019-07-18 8:13 ` Michael S. Tsirkin
2019-07-18 9:37 ` Stefano Garzarella
2019-07-18 11:35 ` Michael S. Tsirkin
2019-07-19 8:08 ` Stefano Garzarella
2019-07-19 8:21 ` Jason Wang
2019-07-19 8:39 ` Stefano Garzarella
2019-07-19 8:51 ` Jason Wang
2019-07-19 9:20 ` Stefano Garzarella
2019-07-22 9:06 ` Stefan Hajnoczi
2019-07-17 11:30 ` [PATCH v4 5/5] vsock/virtio: change the maximum packet size allowed Stefano Garzarella
2019-07-17 14:59 ` Michael S. Tsirkin
2019-07-18 7:52 ` Stefano Garzarella
2019-07-18 12:33 ` Michael S. Tsirkin
2019-07-19 8:29 ` Stefano Garzarella
2019-07-22 9:07 ` Stefan Hajnoczi
2019-07-22 9:08 ` [PATCH v4 0/5] vsock/virtio: optimizations to increase the throughput Stefan Hajnoczi
2019-07-22 9:14 ` Stefano Garzarella
2019-07-29 13:12 ` Stefan Hajnoczi
2019-07-29 13:59 ` Michael S. Tsirkin
2019-07-30 9:40 ` Stefano Garzarella
2019-07-30 10:03 ` Jason Wang
2019-07-30 15:38 ` Stefano Garzarella
2019-09-03 8:02 ` request for stable (was Re: [PATCH v4 0/5] vsock/virtio: optimizations to increase the throughput) Michael S. Tsirkin
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