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Subject: Re: [RFC v1 0/6] virtio/vsock: introduce SOCK_DGRAM support
To:     Jiang Wang <jiang.wang@bytedance.com>, sgarzare@redhat.com
Cc:     virtualization@lists.linux-foundation.org, stefanha@redhat.com,
        mst@redhat.com, arseny.krasnov@kaspersky.com,
        jhansen@vmware.comments, cong.wang@bytedance.com,
        duanxiongchun@bytedance.com, xieyongji@bytedance.com,
        chaiwen.cc@bytedance.com, "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>,
        Colin Ian King <colin.king@canonical.com>,
        Jorgen Hansen <jhansen@vmware.com>,
        Andra Paraschiv <andraprs@amazon.com>,
        Norbert Slusarek <nslusarek@gmx.net>,
        Lu Wei <luwei32@huawei.com>,
        Alexander Popov <alex.popov@linux.com>, kvm@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20210609232501.171257-1-jiang.wang@bytedance.com>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <da90f17a-1c24-b475-76ef-f6a7fc2bcdd5@redhat.com>
Date:   Thu, 10 Jun 2021 09:50:56 +0800
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在 2021/6/10 上午7:24, Jiang Wang 写道:
> This patchset implements support of SOCK_DGRAM for virtio
> transport.
>
> Datagram sockets are connectionless and unreliable. To avoid unfair contention
> with stream and other sockets, add two more virtqueues and
> a new feature bit to indicate if those two new queues exist or not.
>
> Dgram does not use the existing credit update mechanism for
> stream sockets. When sending from the guest/driver, sending packets
> synchronously, so the sender will get an error when the virtqueue is full.
> When sending from the host/device, send packets asynchronously
> because the descriptor memory belongs to the corresponding QEMU
> process.


What's the use case for the datagram vsock?


>
> The virtio spec patch is here:
> https://www.spinics.net/lists/linux-virtualization/msg50027.html


Have a quick glance, I suggest to split mergeable rx buffer into an 
separate patch.

But I think it's time to revisit the idea of unifying the virtio-net and 
virtio-vsock. Otherwise we're duplicating features and bugs.

Thanks


>
> For those who prefer git repo, here is the link for the linux kernel：
> https://github.com/Jiang1155/linux/tree/vsock-dgram-v1
>
> qemu patch link:
> https://github.com/Jiang1155/qemu/tree/vsock-dgram-v1
>
>
> To do:
> 1. use skb when receiving packets
> 2. support multiple transport
> 3. support mergeable rx buffer
>
>
> Jiang Wang (6):
>    virtio/vsock: add VIRTIO_VSOCK_F_DGRAM feature bit
>    virtio/vsock: add support for virtio datagram
>    vhost/vsock: add support for vhost dgram.
>    vsock_test: add tests for vsock dgram
>    vhost/vsock: add kconfig for vhost dgram support
>    virtio/vsock: add sysfs for rx buf len for dgram
>
>   drivers/vhost/Kconfig                              |   8 +
>   drivers/vhost/vsock.c                              | 207 ++++++++--
>   include/linux/virtio_vsock.h                       |   9 +
>   include/net/af_vsock.h                             |   1 +
>   .../trace/events/vsock_virtio_transport_common.h   |   5 +-
>   include/uapi/linux/virtio_vsock.h                  |   4 +
>   net/vmw_vsock/af_vsock.c                           |  12 +
>   net/vmw_vsock/virtio_transport.c                   | 433 ++++++++++++++++++---
>   net/vmw_vsock/virtio_transport_common.c            | 184 ++++++++-
>   tools/testing/vsock/util.c                         | 105 +++++
>   tools/testing/vsock/util.h                         |   4 +
>   tools/testing/vsock/vsock_test.c                   | 195 ++++++++++
>   12 files changed, 1070 insertions(+), 97 deletions(-)
>