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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!nntp.coast.net!sgigate.sgi.com!fido.asd.sgi.com!neteng!lm From: lm@neteng.engr.sgi.com (Larry McVoy) Newsgroups: gnu.misc.discuss,comp.os.linux.networking,comp.unix.bsd.netbsd.misc Subject: Re: TCP latency Followup-To: gnu.misc.discuss,comp.os.linux.networking,comp.unix.bsd.netbsd.misc Date: 20 Jun 1996 07:28:04 GMT Organization: Silicon Graphics Inc., Mountain View, CA Lines: 39 Message-ID: <4qaui4$o5k@fido.asd.sgi.com> References: <4paedl$4bm@engnews2.Eng.Sun.COM> <4pf7f9$bsf@white.twinsun.com> <4qad7d$a5l@verdi.nethelp.no> Reply-To: lm@slovax.engr.sgi.com NNTP-Posting-Host: neteng.engr.sgi.com X-Newsreader: TIN [version 1.2 PL2] Xref: euryale.cc.adfa.oz.au gnu.misc.discuss:26569 comp.os.linux.networking:42286 comp.unix.bsd.netbsd.misc:3803 Steinar Haug (sthaug@nethelp.no) wrote: : [Larry McVoy] : | Rick Jones (raj@cup.hp.com) wrote: : | : Alan Cox (iialan@iifeak.swan.ac.uk) wrote: : | : | : : ----------------------------------------------//// : | : : Yow! 233 microsecond remote host TCP latency ---- beat that : | : : --------------------------------------------////__________ o : | : : Alan Cox, Alan.Cox@linux.org /_____________/ / /\/ /_/ >< : | : | : Is that round-trip, or one-way? : | : | As the guy that got those numbers: it's round trip. FreeBSD numbers on : | the same hardware (the *same* hardware, it's dual boot linux and bsd) : | are around 550. : So what kind of hardware is it? P5@133, ASUS motherboard (I can't remember the model number but it is the really common one, pipeline burst cache), SMC 100Mbit cards using the DEC tulip chip (nice job, DEC). It's a pretty cool number since Sun's was the next best at 280 on a pair of Ultrasparcs - CPUs that have about 2x the integer perf of the P5s. I would imagine that Linux on the ultras would get that number down to about a 140 usecs or so round trip. Note that all is not well in Linux land, however, it scales for shit. When you have multiple sockets in time wait (or connected) the Linux numbers quickly slow down to about the same as the FreeBSD numbers for latency. Linux needs to rethink it's lookup code. -- --- Larry McVoy lm@sgi.com http://reality.sgi.com/lm (415) 933-1804 Copyright 1996, all rights reserved. Microsoft Network is prohibited from redistributing this work in any form, in whole or in part without license. License to distribute this work is available to Microsoft at $500. Transmission without permission constitutes an agreement to these terms.