linux-kernel - Re: [PATCH v4] virtio/vsock: replace virtio_vsock_pkt with sk

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Date:   Thu, 24 Nov 2022 16:00:05 +0100
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     Bobby Eshleman <bobby.eshleman@...edance.com>,
        Krasnov Arseniy <oxffffaa@...il.com>
Cc:     Bobby Eshleman <bobbyeshleman@...il.com>,
        Cong Wang <cong.wang@...edance.com>,
        Jiang Wang <jiang.wang@...edance.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] virtio/vsock: replace virtio_vsock_pkt with sk_buff

This is a net-next material, please remember to use net-next tag:
https://www.kernel.org/doc/html/v6.0/process/maintainer-netdev.html#netdev-faq

On Wed, Nov 23, 2022 at 10:07:49PM -0800, Bobby Eshleman wrote:
>This commit changes virtio/vsock to use sk_buff instead of
>virtio_vsock_pkt. Beyond better conforming to other net code, using
>sk_buff allows vsock to use sk_buff-dependent features in the future
>(such as sockmap) and improves throughput.
>
>This patch introduces the following performance changes:
>
>Tool/Config: uperf w/ 64 threads, SOCK_STREAM
>Test Runs: 5, mean of results
>Before: commit 95ec6bce2a0b ("Merge branch 'net-ipa-more-endpoints'")
>
>Test: 64KB, g2h
>Before: 21.63 Gb/s
>After: 25.59 Gb/s (+18%)
>
>Test: 16B, g2h
>Before: 11.86 Mb/s
>After: 17.41 Mb/s (+46%)
>
>Test: 64KB, h2g
>Before: 2.15 Gb/s
>After: 3.6 Gb/s (+67%)
>
>Test: 16B, h2g
>Before: 14.38 Mb/s
>After: 18.43 Mb/s (+28%)
>
>Signed-off-by: Bobby Eshleman <bobby.eshleman@...edance.com>
>---

The patch LGTM. I run several tests (iperf3, vsock_test,
vsock_diag_test, vhost-user-vsock, tcpdump) and IMO we are okay.

I found the following problems that I would like to report:

- vhost-user-vsock [1] is failing, but it is not an issue of this patch,
   but a spec violation in the rust-vmm/vm-virtio/virtio-vsock crate as I
   reported here [2]. We will fix it there, this patch is fine, indeed
   trying a guest with the new layout (1 descriptor for both header and
   data) with vhost-vsock in Linux 6.0, everything works perfectly.

- the new "SOCK_SEQPACKET msg bounds" [3] reworked by Arseniy fails
   intermittently with this patch.

   Using the tests currently in the kernel tree everything is fine, so
   I don't understand if it's a problem in the new test or in this
   patch. I've looked at the code again and don't seem to see any
   criticisms.

   @Arseniy @Bobby can you take a look?

   I'll try to take a closer look too, and before I give my R-b I'd like
   to make sure it's a problem in the test and not in this patch.

   This is what I have (some times, not always) with both host and guest
   with this patch and the series of [3] applied:

   host$ ./vsock_test --control-host=192.168.133.3 --control-port=12345 \
                      --mode=client --peer-cid=4
   Control socket connected to 192.168.133.3:12345.
   0 - SOCK_STREAM connection reset...ok
   1 - SOCK_STREAM bind only...ok
   2 - SOCK_STREAM client close...ok
   3 - SOCK_STREAM server close...ok
   4 - SOCK_STREAM multiple connections...ok
   5 - SOCK_STREAM MSG_PEEK...ok
   6 - SOCK_SEQPACKET msg bounds...ok
   7 - SOCK_SEQPACKET MSG_TRUNC flag...recv: Connection reset by peer

   guest$ ./vsock_test --control-port=12345 --mode=server --peer-cid=2
   Control socket listening on 0.0.0.0:12345
   Control socket connection accepted...
   0 - SOCK_STREAM connection reset...ok
   1 - SOCK_STREAM bind only...ok
   2 - SOCK_STREAM client close...ok
   3 - SOCK_STREAM server close...ok
   4 - SOCK_STREAM multiple connections...ok
   5 - SOCK_STREAM MSG_PEEK...ok
   6 - SOCK_SEQPACKET msg bounds...Message bounds broken

Thanks,
Stefano

[1] https://github.com/rust-vmm/vhost-device/tree/main/crates/vsock
[2] https://github.com/rust-vmm/vm-virtio/issues/204
[3] https://lore.kernel.org/lkml/c991dffd-1dbc-e1d1-b682-a3c71f6ce51c@sberdevices.ru/