Re: [PATCH 2.6.33] mac80211: fix skb buffering issue

[Lennert Buytenhek <buytenh@wantstofly.org>]

On Tue, Jan 05, 2010 at 12:16:03PM -0500, John W. Linville wrote:

> > Since I removed the master netdev, we've been
> > keeping internal queues only, and even before
> > that we never told the networking stack above
> > the virtual interfaces about congestion. This
> > means that packets are queued in mac80211 and
> > the upper layers never know, possibly leading
> > to memory exhaustion and other problems.
> > 
> > This patch makes all interfaces multiqueue and
> > uses ndo_select_queue to put the packets into
> > queues per AC. Additionally, when the driver
> > stops a queue, we now stop all corresponding
> > queues for the virtual interfaces as well.
> > 
> > The injection case will use VO by default for
> > non-data frames, and BE for data frames, but
> > downgrade any data frames according to ACM. It
> > needs to be fleshed out in the future to allow
> > chosing the queue/AC in radiotap.
> > 
> > Reported-by: Lennert Buytenhek <buytenh@marvell.com>
> > Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
> > Cc: stable@kernel.org [2.6.32]
> > ---
> > I know it's late, and large, but still would be good to have in .33
> > since the issue is fairly serious.
> 
> Obviously I'd like to see some testing.  Lennert, does this
> patch resolve the issues you raised?

I had some QA done on 2.6.32 + this version of the patch (slightly
tweaked to make it apply to .32), and it solves the OOM issues we were
seeing, throughput looks good, the 8% more cpu that 2.6.32 uses
relative to 2.6.31 in the same forwarding test seems to be at least
partially taken care of by this patch, and there haven't been any
stability issues so far.