Date: Mon, 10 Feb 1997 20:25:22 +0100 From: Poul-Henning Kamp <phk@critter.dk.tfs.com> To: Garrett Wollman <wollman@lcs.mit.edu> Cc: Greg Burch <gregb@qosnet.com>, freebsd-current@freefall.freebsd.org, Christoph Kukulies <kuku@gilberto.physik.rwth-aachen.de> Subject: Re: tcp/ip performance miserable Message-ID: <13374.855602722@critter.dk.tfs.com> In-Reply-To: Your message of "Mon, 10 Feb 1997 13:25:00 EST." <9702101825.AA05237@halloran-eldar.lcs.mit.edu>
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In message <9702101825.AA05237@halloran-eldar.lcs.mit.edu>, Garrett Wollman wri tes: Well, should xplot be made part of FreeBSD ? Do you know if the author would be against this ? >For people who have performance problems with TCP, I would strongly >suggest doing a graphical performance analysis with tcpdump and xplot. >It is much easier to figure out problems when one has anaylzed what is >happening. For the record, I get pretty close to the expected value >on the two tests I was able to do from 3.0(current) to Digital UNIX >3.2G and an old 2.2 SNAP. > >The graphical performance analysis technique is described in a >technical report, MIT/LCS/TR-494, by Timothy J. Shepard, entitled >``TCP Packet Trace Analysis''. (It was originally a Masters' thesis.) >The `xplot' program described in the report, along with a Perl script >I wrote to generate xplot input files from tcpdump output, and maybe >also a PostScript version of the TR, is available at ><ftp://mercury.lcs.mit.edu/pub/shep/xplot-0.89.tar.gz>; I should make >a port of it some day. > >The usefulness of this technique cannot be overstated. It is >literally the difference between poring over text traces for three >hours and looking at a plot for five minutes and saying ``aha, there's >a fast-retransmit, and there's where another packet got dropped, so >that delay is a retransmit timeout!'' It's like night and day. > >-GAWollman > >-- >Garrett A. Wollman | O Siem / We are all family / O Siem / We're all the sam >e >wollman@lcs.mit.edu | O Siem / The fires of freedom >Opinions not those of| Dance in the burning flame >MIT, LCS, ANA, or NSA| - Susan Aglukark and Chad Irschick -- Poul-Henning Kamp | phk@FreeBSD.ORG FreeBSD Core-team. http://www.freebsd.org/~phk | phk@login.dknet.dk Private mailbox. whois: [PHK] | phk@tfs.com TRW Financial Systems, Inc. Power and ignorance is a disgusting cocktail.
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