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SubjectRe: Linux-1.3.89
   cc: linux-kernel@vger.rutgers.edu
Date: Tue, 16 Apr 1996 22:46:21 -0400
From: "Eric Schenk" <schenk@cs.toronto.edu>

Robert L Krawitz <rlk@tiac.net> writes:
>FTP performance to a solaris host over PPP (28.8 connection) is still
>slow -- 2.6 KB/sec for uncompressible, 10+ for perfectly
>compressible. Grabbing something from tsx-11 (which is much further
>away), I got 3.1 for a .gz file.

The problem here is on the Solaris end of things. It's just a bit to
anxious to retransmit things. The main problems seem to be
in the algorithm for estimating round trip times, and in the
algorithm to do slow startup on a TCP link. You can help your
performance a bit by picking a smaller value for MRU
on your PPP link. I find performance on a 14.4k link
gets acceptable with an MRU of 552. I'd be interested to
hear what happens with a 28.8 connection. Note that you still
need to transfer at least 60k or so of data before the
cost of the unneeded retransmits starts to be swamped by
the amount of data you are sending.

My PPP connection is actually to a Cisco 2509 router on the same
ethernet as the Solaris host. I can't change the MRU due to a bug in
the Cisco firmware.

--
Robert Krawitz <rlk@tiac.net> http://www.tiac.net/users/rlk/

Member of the League for Programming Freedom -- mail lpf@uunet.uu.net
Tall Clubs International -- tci-request@aptinc.com or 1-800-521-2512


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