Re: [PATCH] tcp: Expose the initial RTO via a new sysctl.

From: David Miller
Date: Wed May 18 2011 - 15:30:52 EST

From: Benoit Sigoure <tsunanet@xxxxxxxxx>
Date: Wed, 18 May 2011 03:43:04 -0700

> Instead of hardcoding the initial RTO to 3s and requiring
> the kernel to be recompiled to change it, expose it as a
> sysctl that can be tuned at runtime. Leave the default
> value unchanged.
> Signed-off-by: Benoit Sigoure <tsunanet@xxxxxxxxx>

If you read the ietf draft that reduces the initial RTO down to 1
second, it states that if we take a timeout during the initial
connection handshake then we have to revert the RTO back up to 3

This fallback logic conflicts with being able to only change the
initial RTO via sysctl, I think. Because there are actually two
values at stake and they depend upon eachother, the initial RTO and
the value we fallback to on initial handshake retransmissions.

So I'd rather get a patch that implements the 1 second initial
RTO with the 3 second fallback on SYN retransmit, than this patch.

We already have too many knobs.
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