Subject: Re: [PATCH net-next] virtio_net: migrate mergeable rx buffers to page frag allocators

From: "Michael S. Tsirkin" <[email-masked]>
Date: Tue, 29 Oct 2013 21:12:50 +0200

On Mon, Oct 28, 2013 at 11:57:21PM -0400, David Miller wrote:
> From: Eric Dumazet <[email-masked]>
> Date: Mon, 28 Oct 2013 16:19:49 -0700
> 
> > On Mon, 2013-10-28 at 15:44 -0700, Michael Dalton wrote:
> >> The virtio_net driver's mergeable receive buffer allocator
> >> uses 4KB packet buffers. For MTU-sized traffic, SKB truesize
> >> is > 4KB but only ~1500 bytes of the buffer is used to store
> >> packet data, reducing the effective TCP window size
> >> substantially. This patch addresses the performance concerns
> >> with mergeable receive buffers by allocating MTU-sized packet
> >> buffers using page frag allocators. If more than MAX_SKB_FRAGS
> >> buffers are needed, the SKB frag_list is used.
> >> 
> >> Signed-off-by: Michael Dalton <[email-masked]>
> >> ---
> > 
> > Signed-off-by: Eric Dumazet <[email-masked]>
> > 
> > Daniel & Francesco, this should address the performance problem you
> > tried to address with ("tcp: rcvbuf autotuning improvements") 
> > 
> > ( http://www.spinics.net/lists/netdev/msg252642.html )
> 
> Applied, thanks everyone.

Hmm that was very quick. It *should* fix a bug, great.
But how about we wait for some Tested-by reports that it actually does?

-- 
MST