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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!nntp.coast.net!news.kei.com!newsfeed.internetmci.com!in2.uu.net!zdc!zdc-e!szdc-e!news From: "John S. Dyson" <toor@dyson.iquest.net> Newsgroups: comp.os.linux.networking,comp.unix.bsd.netbsd.misc,comp.unix.bsd.freebsd.misc Subject: Re: TCP latency Date: Sat, 13 Jul 1996 10:29:33 -0500 Organization: John S. Dyson's home machine Lines: 53 Message-ID: <31E7C0DD.41C67EA6@dyson.iquest.net> References: <4paedl$4bm@engnews2.Eng.Sun.COM> <x7687w1dsr.fsf@oberon.di.fc.ul.pt> <4s220u$nmq@symiserver2.symantec.com> <31E53C2B.41C67EA6@inuxs.att.com> <4s6k8o$4o0@fox.ksu.ksu.edu> <31E6FD92.41C67EA6@dyson.iquest.net> <4s8cuq$ljd@bertrand.ccs.carleton.ca> NNTP-Posting-Host: dyson.iquest.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 3.0b5a (X11; I; FreeBSD 2.2-CURRENT i386) Xref: euryale.cc.adfa.oz.au comp.os.linux.networking:45086 comp.unix.bsd.netbsd.misc:4021 comp.unix.bsd.freebsd.misc:23453 Mike Shaver wrote: > > John S. Dyson (toor@dyson.iquest.net) wrote: > : He made a claim that BSD networking is not as fast as Linux, specifically > : using the no-load latency figure. > > He posted numbers to back up his claim that a given Linux was faster > than a given *BSD under a given load state on given hardware. > > Are you disputing that fact? Would you be so kind as to let us se the > numbers which enlightened you as to the results of the One True > Benchmark. > Yes I am disputing the fact, the fact is that he had said that the TCP latency is faster. Bzzt, that is the wrong conclusion. The TCP latency under NO LOAD is faster. Most people don't understand the difference, but one claim is accurate, and the other is NOT. > Please read his posting in which he says that you _could_ run a couple > lat_tcps in parallel, which wouldn't do much, but you'd at least get > some context switch overhead in there. (Linux's context switches seem > to be pretty peppy as well, though. =) ) > The point is being missed, and this is why either Linus either doesn't know the scalability issues, or he is disinforming. The issue is that when most people who use the OS see the latency problem, it is when the systems are under heavy load, and the latency that was measured by lat_tcp is pretty much meaningless. Does Linux claim that the Linux networking is under heavy load with only THREE connections? Sorry, even I don't believe that one. > > Of course, you might have trouble finding a benchmark that everyone > agrees is `meaningful'. Although you might possess the arrogance to > declare what `most FreeBSD users' consider meaningful, I'm almost > certain Linus will let the Linux community speak for itself. > The only arrogance that I have seen is that certain people are trying to pass off benchmark results with bogus conclusions. I am being skeptical because of the continued INCORRECT conclusions given the benchmark results presented. (Psst, they are misinforming you and I am trying to protect you from that...) Please take a look at lat_tcp, and considering that it is run alone on a machine and there are generally only a few other TCP connections on the machine... How can it POSSIBLY show ANYTHING but NO-LOAD latency? If a claim is made other than NO-LOAD latency, then someone is trying to pull the wool over your eyes... John