Date: Thu, 17 May 2001 17:19:13 -0400 (EDT) From: Kenneth Wayne Culver <culverk@wam.umd.edu> To: "Jon O." <jono@microshaft.org> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: FreeBSD benchmark question Message-ID: <Pine.GSO.4.21.0105171715490.9866-100000@rac1.wam.umd.edu> In-Reply-To: <Pine.BSF.4.10.10105171402510.35393-100000@stuart.microshaft.org>
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> We are testing a VALinux machine running Red Hat 6.2 against a FreeBSD > machine running 4.3-RELEASE. The test consists of running a genetic search > algorithm on both machines and using time to meaure the result. > > I have found the Linux box is much faster after running the search once > and then firing it off again. So, the first run of the test the two > machines are almost exactly as fast. But, the next time the linux box runs > the test it is vastly faster than the FreeBSD box. I believe this has > something to do with caching, but I don't know the specifics. Can this > type of feature work on FreeBSD? I've enabled softupdates but that only > helps a little. > > Also, the linux box seems to run the CPU up to 100% right off the bat when > starting the test. This probably helps it complete the test quickly. > However, the FreeBSD box runs the CPU up more slowly and never reaches > even 75% usage. Is there a way to get the FreeBSD box to hog the processor > right off the bat? > > you could make a script that calls the program, finds its pid, then renices it to a better priority. Other than that I'd assume that if this program you're running accesses the disk a lot, that's the reason for the performance difference you're seeing. You may want to make sure that the disks are basically the same. Also, Linux caches disk data much more aggressively, at the expense of reliability (if you crash with a lot of data not written out in linux, that data will almost certainly be lost). This could also be why FreeBSD is going slower after the first run. Ken To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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