Re: Weird tcp performance differences with 2.0 and 2.2 kernels

Andrea Arcangeli (andrea@e-mind.com)
Fri, 12 Feb 1999 21:16:08 +0100 (CET)


On Fri, 12 Feb 1999, Mike Galbraith wrote:

>ftp.porcupine.org is one of these for me.. _always_ times out when I
>do 'dir' in the /pub/security directory. (tcpdump attached). If I..
> echo 0 > /proc/sys/net/ipv4/tcp_timestamps
>..it works fine. Anyone know why?

Looking at your trace I noticed that ftp.porcupine.org echo the tsval of
the syn in the syn-ack, while linux doesn't. But the timestamp in the syn
and synack should be needed only to initialize paws to avoid wrapped
sequence number, so I think linux is doing a more efficient choice without
echoing the tp->tsrecent in the synack packet. I am not 100% sure though
because I never seen rfc1323.txt before today (and I am not uptodate with
latest tcp-impl-drafts).

Andrea Arcangeli

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