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Date:   Fri, 5 Apr 2019 09:44:14 +0100
From:   Stefan Hajnoczi <stefanha@gmail.com>
To:     Jason Wang <jasowang@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>
Cc:     netdev@vger.kernel.org, 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>,
        Stefano Garzarella <sgarzare@redhat.com>
Subject: Re: [PATCH RFC 4/4] vsock/virtio: increase RX buffer size to 64 KiB
Message-ID: <20190405084414.GE25152@stefanha-x1.localdomain>
References: <20190404105838.101559-1-sgarzare@redhat.com>
 <20190404105838.101559-5-sgarzare@redhat.com>
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On Thu, Apr 04, 2019 at 12:58:38PM +0200, Stefano Garzarella wrote:
> In order to increase host -> guest throughput with large packets,
> we can use 64 KiB RX buffers.
>=20
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
>  include/linux/virtio_vsock.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
> index 6d7a22cc20bf..43cce304408e 100644
> --- a/include/linux/virtio_vsock.h
> +++ b/include/linux/virtio_vsock.h
> @@ -10,7 +10,7 @@
>  #define VIRTIO_VSOCK_DEFAULT_MIN_BUF_SIZE	128
>  #define VIRTIO_VSOCK_DEFAULT_BUF_SIZE		(1024 * 256)
>  #define VIRTIO_VSOCK_DEFAULT_MAX_BUF_SIZE	(1024 * 256)
> -#define VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE	(1024 * 4)
> +#define VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE	(1024 * 64)

This patch raises rx ring memory consumption from 128 * 4KB =3D 512KB to
128 * 64KB =3D 8MB.

Michael, Jason: Any advice regarding rx/tx ring sizes and buffer sizes?

Depending on rx ring size and the workload's packet size, different
values might be preferred.

This could become a tunable in the future.  It determines the size of
the guest driver's rx buffers.

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