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Newsgroups: comp.os.386bsd.misc Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!msunews!uwm.edu!cs.utexas.edu!howland.reston.ans.net!news.sprintlink.net!news.indirect.com!wes From: wes@indirect.com (Barnacle Wes) Subject: Re: How fast? [was: ... slugish ...] Message-ID: <D0ytA9.K0K@indirect.com> Sender: usenet@indirect.com (System Operator) Organization: the Briney (notso) Deep Date: Sat, 17 Dec 1994 17:15:45 GMT References: <1994Nov28.194617.18912@system9.unisys.com> <3bf6ou$pm7@wup-gate.wup.de> <MICHAELV.94Dec9223853@MindBender.HeadCandy.com> <3cs7rd$k1u@news.demos.su> X-Newsreader: TIN [version 1.2.1 [BP] PL2.1] Lines: 21 Ivan Popov (pin@demos.su) wrote: : I tried to compile same package (screen control libraries) : on the same computer (386/25, 4Mb RAM) : under FreeBSD-2.0 (generic kernel) : and under Demos-86 (real mode UNIX for i8086 [sic], using 640K mem : with /tmp in extended memory). : The result: _user_ times used are almost the same (about 17 min) : _real_ times used are: 50 min under Demos-86, : 90 min under FreeBSD-2.0 : The difference between user and real times was due to I/O and swapping. : (BTW in the case of Demos-86 all passes of the compiler and make itself : fit into 640K, hence almost no swapping) Oh, there are a lot of other differences, too. Your real-mode UNIX probably uses a software interrupt for kernel calls, whereas the protected-mode FreeBSD has to use call gates to cross protection rings, and has to do some page-table frobbing, etc. The overhead of a virtual memory system isn't so much surprising as disappointing. Wes Peters