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Date: Mon, 09 Jan 2012 23:52:46 -0800
From: Daniel Colascione <dancol AT dancol DOT org>
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To: cygwin AT cygwin DOT com
Subject: Re: socket performance
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On 1/9/12 11:22 PM, Henry S. Thompson wrote:
> Corinna Vinschen writes:
>=20
>> it's nice to know that you could increase the performance by increasing
>> the buffer sizes.  However, I'm reluctant to implement this as a generic
>> option.  As far as I know the socket buffers are taken from nonpaged poo=
l,
>> so generically using 2 Meg buffers will take a lot of precious resources.
>=20
> And contribute to bufferbloat problems [1] [2] elsewhere!

Large socket buffers don't contribute bufferbloat: a socket's
send-buffer holds bytes, not packets. It sits above TCP on the
networking stack, thus doesn't affect TCP's flow control decisions.
Bufferbloat happens when deep IP-packet buffers confuse TCP's
congestion avoidance, not when the OS feeds bytes to TCP more efficiently.

Of course, using a larger socket buffer _can_ increase the
send(2)-to-wire latency, but that's not quite the same thing as
bufferbloat.


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