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

[Felix Fietkau <nbd@openwrt.org>]

On 2010-01-05 6:16 PM, John W. Linville wrote:
> On Tue, Jan 05, 2010 at 06:00:58PM +0100, Johannes Berg 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 tested this patch on embedded hardware, and it makes a huge difference
there. It fixes some serious TCP throughput drops and latency spikes
that I observed with ath9k earlier.
I think this should be merged ASAP.

- Felix