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Date:   Mon, 10 Jun 2019 14:44:07 +0100
From:   Stefan Hajnoczi <stefanha@gmail.com>
To:     Stefano Garzarella <sgarzare@redhat.com>
Cc:     netdev@vger.kernel.org, kvm@vger.kernel.org,
        "Michael S. Tsirkin" <mst@redhat.com>,
        linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        Stefan Hajnoczi <stefanha@redhat.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH v3 1/5] vsock/virtio: limit the memory used per-socket
Message-ID: <20190610134407.GM14257@stefanha-x1.localdomain>
References: <20190531133954.122567-1-sgarzare@redhat.com>
 <20190531133954.122567-2-sgarzare@redhat.com>
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On Fri, May 31, 2019 at 03:39:50PM +0200, Stefano Garzarella wrote:
> Since virtio-vsock was introduced, the buffers filled by the host
> and pushed to the guest using the vring, are directly queued in
> a per-socket list. These buffers are preallocated by the guest
> with a fixed size (4 KB).
>=20
> The maximum amount of memory used by each socket should be
> controlled by the credit mechanism.
> The default credit available per-socket is 256 KB, but if we use
> only 1 byte per packet, the guest can queue up to 262144 of 4 KB
> buffers, using up to 1 GB of memory per-socket. In addition, the
> guest will continue to fill the vring with new 4 KB free buffers
> to avoid starvation of other sockets.
>=20
> This patch mitigates this issue copying the payload of small
> packets (< 128 bytes) into the buffer of last packet queued, in
> order to avoid wasting memory.
>=20
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
>  drivers/vhost/vsock.c                   |  2 +
>  include/linux/virtio_vsock.h            |  1 +
>  net/vmw_vsock/virtio_transport.c        |  1 +
>  net/vmw_vsock/virtio_transport_common.c | 60 +++++++++++++++++++++----
>  4 files changed, 55 insertions(+), 9 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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