FreeBSD Window updates

Venkat Venkatsubra venkatvenkatsubra at
Sat Nov 29 13:01:54 PST 2008

So the apps read buffer is possibly 32 times 2^8 = 8KB ?
(32 being the increment in each of those window updates.)

From: David Malone <dwmalone at>
To: Venkat Venkatsubra <venkatvenkatsubra at>
Cc: Rui Paulo <rpaulo at>; freebsd-net at; Kevin Oberman <oberman at>
Sent: Saturday, November 29, 2008 2:46:53 PM
Subject: Re: FreeBSD Window updates

> Each of these 5 window updates are sent after the apps completed the read
> that it issued, what's the buffer size the apps is passing to the read?
> If it is small, could that be increased?

I'm not actually sure - the app is iperf. The window scaling factor
is 8 here I think.

> But I agree with you that there is room for optimizing sending of these
> window updates.

Any feeling for which would be the better fix?



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