Date: Mon, 30 Nov 2009 14:23:44 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-questions@freebsd.org Cc: freebsd-stable@freebsd.org Subject: Re: Phoronix Benchmarks: Waht's wrong with FreeBSD 8.0? Message-ID: <hf0h0p$lm4$1@ger.gmane.org> In-Reply-To: <0D3A9408-84A8-4C74-A318-F580B41FC1A6@exscape.org> References: <4B13869D.1080907@zedat.fu-berlin.de> <0D3A9408-84A8-4C74-A318-F580B41FC1A6@exscape.org>
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Thomas Backman wrote: > On Nov 30, 2009, at 9:47 AM, O. Hartmann wrote: > >> I'm just wondering what's wrong with FreeBSD 8.0/amd64 when I read the Benchmarks on Phoronix.org's website. Especially FreeBSD's threaded I/O shows in contrast to all claims that have been to be improoved the opposite. > Corrected link: http://www.phoronix.com/scan.php?page=article&item=freebsd8_benchmarks&num=1 > > And yeah, quite honestly: disk scheduling in FreeBSD appears to suck... The only reason I'm not switching from Linux. :( About the only useful result of the "Phoronix benchmark suite" in general is that benchmarking is hard, and that though tedious, statistical analisys and multiple runs actually have a realistic purpose. I suspect their runs have a very large variance between tests and are only useful in "order-of-magnitude" sort of comparisons. Most of their CPU-bound benchmarks therefore show results with insignificant differences, and most of the others benchmark the compilers. On the other hand, disk IO benchmarks like http://www.phoronix.com/scan.php?page=article&item=freebsd8_benchmarks&num=7 reflect the real state of the things, which can be easily demonstrated by a large number of other benchmarks (e.g. blogbench). AFAIK there is some speculation among developers about why is this so, but nothing definite yet. For what it's worth, ZFS effectively does a fair bit of its own IO scheduling, so persons interested in this particular aspect should also try the tests with ZFS. My own tests (with other benchmarks) show that ZFS helps significantly, though the cumulative result is still significantly worse than Linux's.
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