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Re: [Qemu-devel] [PATCH v2] net: increase buffer size to accommodate Jum


From: Stefan Hajnoczi
Subject: Re: [Qemu-devel] [PATCH v2] net: increase buffer size to accommodate Jumbo frame pkts
Date: Mon, 25 Mar 2013 11:15:03 +0100
User-agent: Mutt/1.5.21 (2010-09-15)

On Mon, Mar 18, 2013 at 11:43:44AM -0700, address@hidden wrote:
> From: Scott Feldman <address@hidden>
> 
> Socket buffer sizes were hard-coded to 4K for VDE and socket netdevs.  Bump 
> this
> up to 68K (ala tap netdev) to handle maximum GSO packet size (64k) plus plenty
> of room for the ethernet and virtio_net headers.
> 
> Originally, ran into this limitation when using -netdev UDP sockets to connect
> VM-to-VM, where VM interface is configure with MTU=9000.  (Using virtio_net
> NIC model).  Test is simple: ping -M do -s 8500 <target>.  This test will
> attempt to ping with unfragmented packet of given size.  Without patch, size
> is limited to < 4K (minus protocol hdrs).  With patch, ping test works with 
> pkt
> size up to 9000 (again, minus protocol hdrs).
> 
> v2: per Stefan, increase buf size to (4096+65536) as done in tap and apply
>     to vde and socket netdevs.
> v1: increase buf size to 12K just for -netdev UDP sockets
> 
> Signed-off-by: Scott Feldman <address@hidden>
> ---
>  include/net/net.h |    5 +++++
>  net/net.c         |    2 +-
>  net/socket.c      |    4 ++--
>  net/tap.c         |    7 +------
>  net/vde.c         |    2 +-
>  5 files changed, 10 insertions(+), 10 deletions(-)

Thanks, applied to my net tree:
https://github.com/stefanha/qemu/commits/net

Stefan



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