From: Ben Greear <greearb@candelatech•com>
To: David Miller <davem@davemloft•net>
Cc: hannes@stressinduktion•org, amwang@redhat•com,
netdev@vger•kernel.org, eric.dumazet@gmail•com,
rick.jones2@hp•com, shemminger@vyatta•com, tgraf@suug•ch,
David.Laight@ACULAB•COM
Subject: Re: [Patch net-next] tcp: add a global sysctl to control TCP delayed ack
Date: Thu, 04 Apr 2013 16:39:04 -0700 [thread overview]
Message-ID: <515E0F18.8080705@candelatech.com> (raw)
In-Reply-To: <20130404.192539.1157364077083658871.davem@davemloft.net>
On 04/04/2013 04:25 PM, David Miller wrote:
> From: Hannes Frederic Sowa <hannes@stressinduktion•org>
> Date: Fri, 5 Apr 2013 00:48:10 +0200
>
>> I totally understand the objections that were given regarding this
>> patch. But for defense of this patch we also provide a knob to disable
>> slow start after idle, which from my point of view is as "evil" as
>> this change.
>
> I completely disagree, slow start after idle is way too aggressively
> throwing past history away, so turning that off is much safer.
I've been carrying a per-socket way to control delayed ack in my tree for a while,
and it is a big performance gain on wifi networks where the network is
basically half-duplex. If I recall correctly, it's worth 50+Mbps
throughput improvement in some cases. If it matters, I can post more
detailed numbers.
There are drawbacks when you set delayed ack too high: The ramp-up time
for TCP takes a good bit longer. But, some applications may want to trade
slower startup time for better bulk transport, and at moderate delayed-ack
values, the ramp up time is not noticeably impaired.
Thanks,
Ben
--
Ben Greear <greearb@candelatech•com>
Candela Technologies Inc http://www.candelatech.com
next prev parent reply other threads:[~2013-04-04 23:39 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-04 10:16 [Patch net-next] tcp: add a global sysctl to control TCP delayed ack Cong Wang
2013-04-04 22:48 ` Hannes Frederic Sowa
2013-04-04 23:25 ` David Miller
2013-04-04 23:39 ` Ben Greear [this message]
2013-04-06 15:38 ` Hagen Paul Pfeifer
2013-04-07 21:09 ` David Miller
2013-04-08 1:45 ` Cong Wang
2013-04-08 16:39 ` Rick Jones
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