Date: Sat, 5 Jun 2010 19:41:23 +0200 From: Attilio Rao <attilio@freebsd.org> To: Matthew Jacob <mj@feral.com> Cc: freebsd-hackers@freebsd.org Subject: Re: sysbench / fileio - Linux vs. FreeBSD Message-ID: <AANLkTikZY65hJO7gLldYSVn7vts84fou64kipWsH0y0i@mail.gmail.com> In-Reply-To: <4C0A816A.9040403@feral.com> References: <4C09932B.6040808@wooh.hu> <201006050236.17697.bruce@cran.org.uk> <4C09FC43.8070804@wooh.hu> <4C0A7F2F.3030105@elischer.org> <4C0A816A.9040403@feral.com>
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2010/6/5 Matthew Jacob <mj@feral.com> > > All of these tests have been apples vs. oranges for years. > > The following seems to be true, though: > > a) FreeBSD sequential write performance in UFS has always been less than = optimal. > > b) Linux sequential write performance in just about any filesystem has al= ways been "impressive". But that "impressive" has come at some not so obvio= us costs. First of all, Linux is probably the most aggressive cluster/write= -behind OS I've even seen. You can suck down all available memory with writ= ebehind using dd. This means that some stats are "impressive", and others a= re "painful". A desktop that becomes completely unresponsive while you're d= oing this dd is one personal outcome. > > Also, you have to be careful what you're asking for in comparing the two = platforms, or any platforms for that matter. What do you want to optimize f= or? Apparent responsiveness as a desktop? A specific workload (nfs, cifs) t= hat completes N quatloos per fortnight? Besides anything, I'm much more concerned about the loss of performance within FreeBSD itself. I wouldn't expect a so high pessimization when the number of threads increases (without considering the big performance loss with the 8k blocksize, pretty much reproducible). I'm trying to drive, privately, the tester to pmc/lock profiling analysis in order to start collecting some useful datas. While I think that we might pay a lot of attention to ZFS, I think we might not leave alone FFS. Having a fast, well supported, native filesystem might be a great thing for us. Comparing with other operating systems, as you smartly point out, might not be got as 'undefeatable truths' but have cons and prons that needs to be fully understood before to make false claims. Thanks, Attilio -- Peace can only be achieved by understanding - A. Einstein
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