Subject: Re: Strange network performance problem with -current and 1.6_BETA1
To: Markus W Kilbinger <firstname.lastname@example.org>
From: Manuel Bouyer <email@example.com>
Date: 06/10/2002 22:39:44
On Mon, Jun 10, 2002 at 10:20:32PM +0200, Markus W Kilbinger wrote:
> >>>>> "Manuel" == Manuel Bouyer <firstname.lastname@example.org> writes:
> Manuel> On Mon, Jun 10, 2002 at 02:57:32AM +0200, Markus W Kilbinger wrote:
> >> [...]
> >> - If 'who' is a -current or 1.6_BETA1 machine (no matter what
> >> hardware, I see it with i386, alpha, sparc, macppc) ftp upload to
> >> the internet becomes incredibly slow (starting with about 80 kb/sec,
> >> falling down to about 10 kb/sec).
> Manuel> Did you look at differences in sysctl settings ?
> Very good guess! The causing difference is:
> < net.inet.tcp.cwm = 0
> > net.inet.tcp.cwm = 1
> It's '0' in 1.5_RC2 and '1' in 1.6*. What does this kernel
> variable/flag mean?
Returns 1 if use of the Hughes/Touch/Heidemann Congestion
Window Monitoring algorithm is enabled. This algorithm
prevents line-rate bursts of packets that could otherwise
occur when data begins flowing on an idle TCP connection.
These line-rate bursts can contribute to network and
router congestion. This can be particularly useful on
World Wide Web servers which support HTTP/1.1, which has
> I didn't change anything in my config relating
> this... So it's a new default in 1.6*?
Manuel Bouyer <email@example.com>