On Mon, Jun 10, 2002 at 10:20:32PM +0200, Markus W Kilbinger wrote:
> >>>>> "Manuel" == Manuel Bouyer <bouyer@antioche.eu.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?

From sysctl(2)
             tcp.cwm
                     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
                     lingering connections.


> I didn't change anything in my config relating
> this... So it's a new default in 1.6*?

Yes.

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
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