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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!nntp.coast.net!zombie.ncsc.mil!news.mathworks.com!nntp.primenet.com!winternet.com!news2.interlog.com!nntp.uio.no!news.global-one.no!news1.transpac.net!news1.global-one.dk!news.uni-c.dk!kroete2!not-for-mail From: ehcorry@inet.uni-c.dk (Erik Corry) Newsgroups: comp.os.linux.networking,comp.unix.bsd.netbsd.misc,comp.unix.bsd.freebsd.misc Subject: Re: TCP latency Followup-To: comp.os.linux.networking,comp.unix.bsd.netbsd.misc,comp.unix.bsd.freebsd.misc Date: Mon, 15 Jul 1996 23:50:58 GMT Organization: Home Lines: 79 Sender: news@kroete2.freinet.de (news) Message-ID: <DuLzKz.Fsy@kroete2.freinet.de> References: <4paedl$4bm@engnews2.Eng.Sun.COM> <31E7C0DD.41C67EA6@dyson.iquest.net> <4s8tcn$jsh@fido.asd.sgi.com> <31E80ACA.167EB0E7@dyson.iquest.net> <4sadde$qsv@linux.cs.Helsinki.FI> <31EA9FBC.41C67EA6@star-gate.com> NNTP-Posting-Host: arh56.ppp.uni-c.dk Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Newsreader: TIN [UNIX 1.3 950515BETA PL0] Xref: euryale.cc.adfa.oz.au comp.os.linux.networking:45271 comp.unix.bsd.netbsd.misc:4055 comp.unix.bsd.freebsd.misc:23614 Amancio Hasty Jr. (hasty@star-gate.com) wrote: : Linus Torvalds wrote: : > : > In article <31E80ACA.167EB0E7@dyson.iquest.net>, : > John S. Dyson <toor@dyson.iquest.net> wrote: : > >Larry McVoy wrote: : > > : > >> It's kind of fun to contrast this with the Linux crowd: : > >> : > >> BSD guys: "your benchmark sucks! your numbers are wrong! you mislead the : > >> world! you suck! whine!" : > >> : > >> Linux guys: "Hey Larry, the null syscall benchmark is busted because we can : > >> do a null syscall in about 1 usec. You need to change it so : > >> it times in nanoseconds". : > > : > >I think that was a kind-of cute situation. We decided NOT : > >to special case the syscall that Larry uses for the : > >null-syscall case. : > : > John, John, John, calm down. : > : > You are suggesting above that YOU did not special case the system call : > that Larry uses in lmbench, and by implication you are claiming Linux : > does. Very subtly done, but : > : > YOU'RE LYING : : May I ask in which point do you think that Dyson is lying? 8) I think what John wrote above can only be interpreted as a complaint that Linux has a special case for the null syscall. I certainly interpreted it that way, so did Linus, and so did most people reading the message. If nobody special-cased the null syscall, why bring it up at all. Linus's reaction at apparently being accused of cheating was understandable (and much more moderate than John's "you are an arrogant, self-righteous a**hole" answer). John now denies that he meant to imply cheating by Linus. It would have been appropriate to clarify his position, apologise for being so unclear and drop the rest of the post, which (apparently) was based on a misunderstanding of John's post by Linus. Instead, John went ballistic, with shouting and ranting. He also wrote: > We could have special cased it to make the benchmark look better, but > we did not. We have looked at it carefully, and it has little impact > on real-world performance. Historically, a NULL syscall is not > a write to /dev/null... That is what the benchmark is, and simply > it is NOT IMPORTANT. It looks from this as if John thinks the reason Larry benchmarks the null syscall is that Larry thinks people want to do thousands of null syscalls per second. Of course the null syscall isn't important, it's just a way of measuring the syscall overhead when you make a useful syscall. And that (I hope everyone can agree) is an interesting figure. If John thinks there's a better (historical?) way to test that overhead he doesn't say what it is. Amancio Hasty again: : Linus: : >beat you on system call latency (and I have to admit that I haven't even : >looked at the FreeBSD numbers, so I'm just assuming that from your post : : If anyone needs to calm down around here is you, *linus*. Please : don't assume either ask for the numbers or get them yourselves. The numbers have just been posted, and in fact Linux does get better figures. Again Linus's assumption was fully justified: if FreeBSDs figures were better, why would John feel the need to apologise for them? : we still don't know its configuration nor its OS version -- very very : subtle, linus 8) You haven't been paying attention in this thread then. -- Erik Corry ehcorry@inet.uni-c.dk http://inet.uni-c.dk/~ehcorry/ +45 86166287