netdev - Re: [PATCH] TCP_FAILFAST: a new socket option to timeout/abort a connection quicker

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Message-ID: <4C73DE32.1030802@nets.rwth-aachen.de>
Date:	Tue, 24 Aug 2010 16:58:58 +0200
From:	Arnd Hannemann <hannemann@...s.rwth-aachen.de>
To:	Hagen Paul Pfeifer <hagen@...u.net>
CC:	Eric Dumazet <eric.dumazet@...il.com>,
	"H.K. Jerry Chu" <hkchu@...gle.com>, ilpo.jarvinen@...sinki.fi,
	davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH] TCP_FAILFAST: a new socket option to timeout/abort a
 connection quicker

Hi,

Am 24.08.2010 11:10, schrieb Hagen Paul Pfeifer:
> 
> On Tue, 24 Aug 2010 10:04:37 +0200, Arnd Hannemann wrote:
> 
>> Why not call it TCP_USERTIMEOUT?
> 
>> Later you can also send it via the TCP user timeout option... (RFC5482)
> 
>> Hmm... is the ms granularity really needed? Does it make sense to abort
> 
>> a connection below a second?
> 
> 
> 
> I am working on a patch for UTO, the lion share is already implemented. As

Nice, so did you come up with a name for the socket option yet?

> I can see this patch introduce a upper limit (max) where UTO on the other
> 
> hand provides a lower limit (min). Therefore I am not sure if we should
> 
> call this option TCP_USERTIMEOUT.

Hmm, is there really a difference? If an application specifies
a wanted timeout e.g. with USER_TIMEOUT, CHANGEABLE will
become false and the value would be announced via ADV_UTO.
The connection could be aborted locally after that time passed,
regardless of what the remote site thinks the timeout should be.

As I understand it U_LIMIT and L_LIMIT would only be there
for safety to disallow nonsensical values of USER_TIMEOUT.

Did I miss something?

Best regards,
Arnd
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