Re: [PATCH RFC 0/4] vsock/virtio: optimizations to increase the throughput

From: Stefano Garzarella <sgarzare@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: netdev@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH RFC 0/4] vsock/virtio: optimizations to increase the throughput
Date: Tue, 9 Apr 2019 11:13:00 +0200	[thread overview]
Message-ID: <20190409091300.uozhdyikycb5blmn@steredhat> (raw)
In-Reply-To: <a98d194d-e257-41ff-82e7-de2d16d2f4d4@redhat.com>

On Mon, Apr 08, 2019 at 02:43:28PM +0800, Jason Wang wrote:
> 
> On 2019/4/4 下午6:58, Stefano Garzarella wrote:
> > This series tries to increase the throughput of virtio-vsock with slight
> > changes:
> >   - patch 1/4: reduces the number of credit update messages sent to the
> >                transmitter
> >   - patch 2/4: allows the host to split packets on multiple buffers,
> >                in this way, we can remove the packet size limit to
> >                VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE
> >   - patch 3/4: uses VIRTIO_VSOCK_MAX_PKT_BUF_SIZE as the max packet size
> >                allowed
> >   - patch 4/4: increases RX buffer size to 64 KiB (affects only host->guest)
> > 
> > RFC:
> >   - maybe patch 4 can be replaced with multiple queues with different
> >     buffer sizes or using EWMA to adapt the buffer size to the traffic
> 
> 
> Or EWMA + mergeable rx buffer, but if we decide to unify the datapath with
> virtio-net, we can reuse their codes.
> 
> 
> > 
> >   - as Jason suggested in a previous thread [1] I'll evaluate to use
> >     virtio-net as transport, but I need to understand better how to
> >     interface with it, maybe introducing sk_buff in virtio-vsock.
> > 
> > Any suggestions?
> 
> 
> My understanding is this is not a must, but if it makes things easier, we
> can do this.

Hopefully it should simplify the maintainability and avoid duplicated code.

> 
> Another thing that may help is to implement sendpage(), which will greatly
> improve the performance.

Thanks for your suggestions!
I'll try to implement sendpage() in VSOCK to measure the improvement.

Cheers,
Stefano