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

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Message-ID: <AANLkTimsVzH_aNkN3ZS+AuzvJBTVea8GKLPXanWYMe3t@mail.gmail.com>
Date:	Tue, 24 Aug 2010 13:47:11 -0700
From:	Jerry Chu <hkchu@...gle.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	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

On Mon, Aug 23, 2010 at 11:44 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> Le lundi 23 août 2010 à 23:20 -0700, H.K. Jerry Chu a écrit :
>> From: Jerry Chu <hkchu@...gle.com>
>>
>> This is a TCP level socket option that takes an unsigned int to specify
>> how long in ms TCP should resend a lost data packet before giving up
>> and returning ETIMEDOUT. The normal TCP retry/abort timeout limit still
>> applies. In other words this option is only meant for those applications
>> that need to "fail faster" than the default TCP timeout. The latter
>> may take upto 20 minutes in a normal WAN environment.
>>
>> The option is disabled (by default) when set to 0. Also it does not
>> apply during the connection establishment phase.
>>
>> Signed-off-by: H.K. Jerry Chu <hkchu@...gle.com>
>
> TCP_FAILFAST might be misleading. It reads as a boolean option, while
> its an option to cap the timeout, with a time unit, instead of the usual
> "number of retransmits".

I'm open to better names. Perhaps it can be combined with TCP_UTO
mentioned in subsequent reply?

>
> Its also funny you dont ask for a default value, given by a sysctl
> tunable ;)

This socket option takes time unit directly. The other sysctls
use # of retries and max_rto. (Not sure if that's what you asked.)

>
>
>
>
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