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Date: Thu, 12 Dec 2002 22:26:55 -0800
From: Nivedita Singhvi <niv@us.ibm.com>
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To: Matti Aarnio <matti.aarnio@zmailer.org>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Andreani Stefano <stefano.andreani.ap@h3g.it>,
       "David S. Miller" <davem@redhat.com>,
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Subject: Re: R: Kernel bug handling TCP_RTO_MAX?
References: <047ACC5B9A00D741927A4A32E7D01B73D66178@RMEXC01.h3g.it> <1039727809.22174.38.camel@irongate.swansea.linux.org.uk> <3DF94565.2C582DE2@us.ibm.com> <20021213033928.GK32122@mea-ext.zmailer.org> <3DF965E4.95DEA1F9@us.ibm.com>
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Nivedita Singhvi wrote:

> our default init rto is 300, so currently we're going to timeout
> on anything thats a 100ms over the min of 200. that is far
> less conservative than setting an rto of 200 when your round
> trip time is a thousand or 10,000 times less..does that make sense?

Doh! init rto is NOT 300ms, its 3 seconds. That minor blooper
shreds my comparison argument a tad :)..but Dave's point renders
that moot, in any case..

"David S. Miller" wrote:

> Actually, TCP_RTO_MIN cannot be made any smaller without
> some serious thought.
> 
> The reason it is 200ms is due to the granularity of the BSD
> TCP socket timers.
> 
> In short, the repercussions are not exactly well known, so it's
> a research problem to fiddle here.

Ack.

Sometime in the not too distant future, the next generation of 
infrastructure will require this to be reworked  :).

thanks,
Nivedita
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