Re: Weird tcp performance differences with 2.0 and 2.2 kernels

Andi Kleen (ak@muc.de)
Fri, 12 Feb 1999 15:58:18 +0100


On Fri, Feb 12, 1999 at 08:09:43AM +0100, Mike Galbraith wrote:
> On Fri, 12 Feb 1999, David C Niemi wrote:
>
> >
> > Users are reporting odd and unpleasant FTP hangs on ftp.tux.org as well,
> > which is now running 2.2.1 with the latest fixed wu-ftpd. These problems
> > did not occur with the 2.0.36 kernel but did with 2.2pre6; I'm not quite
> > sure whether they occured in the 2.1.126-8 era because the UP flu made
> > things unusable back then.
> >
> > The hangs do not ALWAYS happen, they are more likely on more remote
> > connections and on connections via firewalls (in the latter case the
> > connections work fine for a similar FTP server running 2.0.36 and used to
> > work fine for ftp.tux.org prior to 2.2.x.
>
> 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?

Probably your terminal server has broken VJ compression. Try turning VJ
compression off on your link.

-Andi

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