Date: Wed, 23 May 2001 13:00:30 -0400 (EDT) From: "Andresen,Jason R." <jandrese@mitre.org> To: Kris Kennaway <kris@obsecurity.org> Cc: Nadav Eiron <nadav@cs.Technion.AC.IL>, <hackers@FreeBSD.ORG> Subject: Re: technical comparison Message-ID: <20010523125626.V87377-100000@nausicaa.mitre.org> In-Reply-To: <20010523095442.B9896@xor.obsecurity.org>
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On Wed, 23 May 2001, Kris Kennaway wrote: > On Wed, May 23, 2001 at 08:17:12AM -0400, Andresen,Jason R. wrote: > > > > Did you enable write caching? You didn't mention, and it's off by > > > default in 4.3, but I think enabled by default on Linux. > > > > I tried to leave the FreeBSD and Linux boxes as unchanged as possible for > > my tests (they are lab machines that have other uses, although I made sure > > they were idle during the test periods). > > > > I left write caching enabled in the Linux boxes, and left it disabled on > > the FreeBSD boxes. Personally, I'm hesitant to enable write caching > > on FreeBSD because we tend to use it on machines where we really really > > don't want to lose data. Write caching is ok on the Linux machines > > because we use them as pure testbeds that we can reconstruct easily if > > their disks go south. > > That's all well and good, but I thought the aim here was to compare > Linux and FreeBSD performance on as level playing field as possible? > You're not measuring FS performance, you're measuring FS performance > plus cache performance, so your numbers so far tell you nothing > concrete. Yes, they tell us that FreeBSD with softupdates and no write cache performs better in large cases than Linux with ext2fs and write caching enabled. Also my FreeBSD 4.0 boxes don't have the hw.ata.wc knob, so it's harder for me to test this. Also, I don't know how ones goes about disabling the write cache in Linux without recompiling the kernel (which we have some custom mods in place, so I'm reluctant to do this). To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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