Date: Sat, 11 Nov 1995 10:02:43 +0100 (MET) From: grog@lemis.de (Greg Lehey) To: rminnich@Sarnoff.COM (Ron G. Minnich) Cc: hackers@freebsd.org (FreeBSD Hackers) Subject: Re: larry: you might want to add this to lmbench (but i'm not sure) Message-ID: <199511110902.KAA19222@allegro.lemis.de> In-Reply-To: <Pine.SOL.3.91.951110110255.13530A-100000@morse> from "Ron G. Minnich" at Nov 10, 95 11:15:34 am
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Ron G. Minnich writes: > > this program does a very simple thing: > 1) open a file > 2) call write with an invalid address, viz: > write(fd, x, 5); > where x is (void *) 0x40000000 > > it does this as many times as you ask. What it's measuring is correlated > to the raw performance of the system's ability to look up a vm region or > segment or object given a virtual address. It is not a pure measure, > since systems that do a lot of work before checking the arguments > (freebsd) will fare worse than systems that just check the arguments up > front for validity (linux). On the other hand, all the system calls that > happen a lot have to do this operation, so you probably want this type of > thing to be fast. Forgive me if I'm not critical :-) I just tried it out on two 486DX/2-66s, one running BSD/386 1.1 and the other running FreeBSD 951004 SNAP. I think the numbers (for 100000 iterations) speak for themselves. BSD/386: 10.19 real 0.33 user 9.61 sys FreeBSD: 54.25 real 0.82 user 52.67 sys People may argue that this is a silly benchmark, but I still think we should be interested to know why FreeBSD takes over 5 times as long to run this program. Greg
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