From: Ben Greear <greearb@candelatech.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: netdev <netdev@vger.kernel.org>
Subject: Re: tcp wifi upload performance and lots of ACKs
Date: Mon, 04 Jun 2012 13:12:20 -0700 [thread overview]
Message-ID: <4FCD16A4.9070705@candelatech.com> (raw)
In-Reply-To: <1338838352.2760.1906.camel@edumazet-glaptop>
On 06/04/2012 12:32 PM, Eric Dumazet wrote:
> On Mon, 2012-06-04 at 11:29 -0700, Ben Greear wrote:
>> I'm going some TCP performance testing on wifi -> LAN interface connections. With
>> UDP, we can get around 250Mbps of payload throughput. With TCP, max is about 80Mbps.
>>
>> I think the problem is that there are way too many ACK packets, and bi-directional
>> traffic on wifi interfaces really slows things down. (About 7000 pkts per second in
>> upload direction, 2000 pps download. And the vast majority of the download pkts
>> are 66 byte ACK pkts from what I can tell.)
>>
>> Kernel is 3.3.7+
>>
>> Anyone know of any tuning parameters that would let the receiving socket wait a
>> bit longer and send more ACK data in fewer packets?
>
> Well, thats half duplex days...
WiFi is still half-duplex, and isn't changing any time soon I think.
> There is the ACK every 2 packets rule of thumb, so that tcp sender can
> increase its cwnd.
>
> Then, some folks tried submitting patches to make '2' more like 10 or
> 15, but this went nowhere.
>
> Other idea is to arm a timer and defer ACK sending, in the hope we
> receive another packet very soon.
From a quick read of Daniel's patch..it seems there is already a
timer that could be used for this?
> That could be done with a special qdisc, sort of netem...
That sounds like a horrible hack :)
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
next prev parent reply other threads:[~2012-06-04 20:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-04 18:29 tcp wifi upload performance and lots of ACKs Ben Greear
2012-06-04 19:22 ` Daniel Baluta
2012-06-04 20:09 ` Ben Greear
2012-06-04 20:15 ` Daniel Baluta
2012-06-07 0:26 ` Ben Greear
2012-06-07 0:40 ` Ben Greear
2012-06-07 4:15 ` Ben Greear
2012-06-07 12:20 ` David Laight
2012-06-07 14:41 ` Ben Greear
2012-06-07 17:51 ` Rick Jones
2012-06-07 18:10 ` David Miller
2012-06-04 19:32 ` Eric Dumazet
2012-06-04 20:12 ` Ben Greear [this message]
2012-06-04 20:18 ` Eric Dumazet
2012-06-05 14:28 ` Glen Turner
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