Date: Thu, 27 Jan 2005 18:04:31 -0700 From: Nick Pavlica <linicks@gmail.com> To: Robert Watson <rwatson@freebsd.org> Cc: Mike Tancsa <mike@sentex.net> Subject: Re: FreeBSD 5.3 I/O Performance / Linux 2.6.10 | Continued Discussion Message-ID: <dc9ba04405012717045622a60f@mail.gmail.com> In-Reply-To: <Pine.NEB.3.96L.1050127002905.26815X-100000@fledge.watson.org> References: <6.2.0.14.0.20050126150959.0466f4b8@64.7.153.2> <Pine.NEB.3.96L.1050127002905.26815X-100000@fledge.watson.org>
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> The move to an MPSAFE VFS will help with that a lot, I should think. Do you know if this will find it's way to 5.x in the near future? > > Also, while on face value this may seem odd, could you try the following > additional variables: > > - Layer the test UFS partition directly over ad0 instead of ad0s1a > - UFS1 vs UFS2 I just tested with UFS1 and had almost the exact same results. > > Finally, in as much as is possible, make sure that the layout of the disks > is approximately the same -- as countless benchmarking papers show, there > are substantial differences (10%+) in I/O throughput depending on where on > the disk surface operations occur. That's one of the reasons to try UFS1 > for the test partition, although not the only one. My tests use the exact same disk layout, and hardware. However, I have had consistent results on all 4 boxes that I have tested on. At this point I'm making the assumption that the poor disk I/O performance on 5.3 isn't a file system issue, but is tied to a larger issue with the Kernel (I know never make assumptions ... :)). In all my testing, I have noticed that 5.3 doesn't appear to release cpu resources even if there isn't any other demand for resources. I would compare it to driveling a car with a governor on it. When I tested with 4.11, it allocated considerably more resources. I do hope that the 5.x issues are resolved soon so that I can deploy may production servers on it rather than starting on 4 and them making the big switch. I will probably test 6 for the fun of it. Thanks! --Nick Pavlica
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