netdev - Re: [PATCH] tcp: make TCP quick ACK behavior modifiable

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Message-ID: <20100823231726.GK2973@ghostprotocols.net>
Date:	Mon, 23 Aug 2010 20:17:26 -0300
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	David Miller <davem@...emloft.net>
Cc:	chris.snook@...il.com, hagen@...u.net, eric.dumazet@...il.com,
	netdev@...r.kernel.org, ilpo.jarvinen@...sinki.fi,
	shemminger@...tta.com
Subject: Re: [PATCH] tcp: make TCP quick ACK behavior modifiable

Em Mon, Aug 23, 2010 at 03:23:30PM -0700, David Miller escreveu:
> From: Chris Snook <chris.snook@...il.com>
> Date: Mon, 23 Aug 2010 18:19:45 -0400
> 
> > Just because we've allowed stupid TCP sysctls in the past does not
> > mean we should continue to do so now.  We recently made delayed ack a
> > per-route tunable, so consistency would suggest we do the same here.
> > Per-route tunables are more flexible, and as with the delayed ack
> > patch, there are use cases where that granularity gives a clear
> > advantage over a sysctl.  For example, you may want to disable quick
> > ack on a high-MTU path and enable it on a low-MTU path.
> > 
> > If you need a hint for how to implement the per-route tunable, look
> > for the delayed ack patch from early 2009.
> 
> I completely agree with Chris that this should be a per-route rather
> than a global sysctl tunable.

My first impression was not so strong as to participate, if every
tunable gets a knob, well, we'd be flying concordes in no time.

But even with such reaction, I thought that if a tunable would be
interesting to have would be a setsockopt one, that knowledgeable,
performance/latency hungry actors would jump into as if they were really
hungry.

And yes, that knob I worked on got lost along the way, I guess I have to
think again about it and submit.

- Arnaldo
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