To: tsuna <tsunanet@gmail.com>
Subject: Re: [PATCH] tcp: Expose the initial RTO via a new sysctl.
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Date: Tue, 31 May 2011 17:25:22 +0200
From: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: "H.K. Jerry Chu" <hkjerry.chu@gmail.com>,
        David Miller <davem@davemloft.net>, <kuznet@ms2.inr.ac.ru>,
        <pekkas@netcore.fi>, <jmorris@namei.org>, <yoshfuji@linux-ipv6.org>,
        <kaber@trash.net>, <netdev@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
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On Tue, 31 May 2011 07:48:09 -0700, tsuna <tsunanet@gmail.com> wrote:

> I talked to Jerry and he's agreed to share some patches that Google
> has been using internally for years.

Great!

> Personally what I think would be ideal would be:
>   1. A sysctl knob for initRTO, to allow people to adjust this
> appropriately for their environment.
>   2. Apply the srtt / rttvar seen on previous connections to new
>   connections.
> 
> Does that sound reasonable?
> 
> For 2), I'm not sure how the details would work yet, I believe the
> kernel already has what's necessary to remember these things on a per
> peer basis, but it would be nice if I could specify things like "for
> 10.x.0.0/16 (local datacenter) use this aggressive setting, for
> 10.0.0.0/8 (my internal backend network) use that, for everything else
> (Internets etc.) use the default".

Skip sysctl, it is deprecated. The initRTO is the ideal candidate for a
per route knob. And happily you will solve 2) with the per route thing too!
;-)

Search the web, you will find some patches where you can see how to extend
the per route system - including iproute2.

Hagen
   
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