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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!news.rmit.EDU.AU!news.unimelb.EDU.AU!munnari.OZ.AU!news.Hawaii.Edu!news.uoregon.edu!hunter.premier.net!news.nl.innet.net!INnl.net!feed1.news.erols.com!howland.erols.net!EU.net!newsfeed.internetmci.com!uunet!in3.uu.net!ulowell.uml.edu!usenet From: no_junk_mail_please@jupiter.cs.uml.edu (Albert D. Cahalan) Newsgroups: comp.os.linux.development.system,comp.unix.bsd.freebsd.misc Subject: Re: Linux vs FreeBSD disk io performance Date: 24 Oct 1996 17:06:26 -0400 Organization: cs Lines: 29 Sender: acahalan@jupiter.cs.uml.edu Message-ID: <vc7pw28gjhp.fsf@jupiter.cs.uml.edu> References: <86g23ey1uc.fsf@romulus.ihosteng.priv.no> <545di1$tvd@halon.vggas.com> <32667BBA.12A8@indy.celebration.net> <54nkti$oh9@bmdhh222.bnr.ca> NNTP-Posting-Host: jupiter.cs.uml.edu In-reply-to: chriseb@nortel.ca's message of 24 Oct 1996 11:45:54 GMT To: chriseb@nortel.ca (Chris (C.) Ebenezer) X-Newsreader: Gnus v5.1 Xref: euryale.cc.adfa.oz.au comp.os.linux.development.system:34120 comp.unix.bsd.freebsd.misc:29958 chriseb@nortel.ca (Chris (C.) Ebenezer) writes: >>>>To see this you who have both operating systems installed can start >>>>the command: dd if=/dev/<root partition> of=/dev/null bs=409600& >>>>4 times a minute apart. After doing this try the df command or a ls -l >>>>on both systems. On the FreeBSD system I barly notice that something >>>>is going on. The linux systems feals realy clumsy. This is on the same >>>>machine. >>>> >>>>Can someone explain this different behaviour? >>> >>> Under linux, df does a sync(). >>> >> Try GNU df or ls under FreeBSD to see if there is a difference. >> FreeBSD does not accumulate nearly as many dirty blocks as >> Linux, and so will probably behave better even using the >> GNU tools. > > And besides the sync() call with Linux doesn't actually write > the disk blocks as has been pointed out earlier, so basically > theer are other factors involved here that cause the delay with > Linux's df. No, it does write the disk blocks. At one time it did not, and on many other unix clones it does not. Linux 1.2 and 2.0 will actually sync the disks as would seem logical and useful. -- -- Albert Cahalan acahalan at cs.uml.edu (no junk mail please - I will hunt you down)