Date: Thu, 02 Mar 2000 19:54:23 +0000 From: Harry Newton <harry_newton@telinco.co.uk> To: freebsd-questions@freebsd.org Subject: Help wanted on interpreting benchmarks Message-ID: <200003021954.TAA14371@chimaera.locus>
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Hi, I have just changed from Debian 2.1 Linux to FreeBSD 3.3-R, running on Pentium 133 with 64M and an ATA hard drive (UDMA compatible). I decided to benchmark the two systems and should like any comments on the results I obtained. Of course, this is not a life-or-death matter as my main reason for changing over to BSD was the (hopefully) greater stability (1). I was just a little curious over the tests. I used unixbench-4.0.1. This runs various tests on the machine and computes a final merit figure, which of course has no meaning. Of more interest are the individual test results. First the file I/O tests: these use the kernel calls write and read. File I/O 1024 bufsize 2000 maxblocks kB/sec Read Write Copy Linux 2.0.36 32525.0 36504.0 19071.0 Linux 2.2.13 31682.0 41044.0 19727.0 Vanilla BSD 19576.0 4088.0 3212.0 BSD + DMA 20476.0 6666.0 6110.0 BSD + DMA + async 20165.0 7200.0 6249.0 BSD + softupdates 19609.0 5955.0 6405.0 File I/O 4096 bufsize 8000 maxblocks kB/sec Read Write Copy Linux 2.0.36 36059.0 10737.0 5562.0 Linux 2.2.13 34869.0 43198.0 21629.0 Vanilla BSD 31994.0 4800.0 3987.0 BSD + DMA 32488.0 7200.0 6952.0 BSD + DMA + async 32469.0 7200.0 7003.0 BSD + softupdates 32481.0 7021.0 7136.0 Things I understand are: read rate is similar, with some dependence on buffer size. What I don't understand fully: why async and softupdates don't appear to make any difference in the write and copy tests. The only thing that appears that to make any difference is switching on DMA. I'm not sure whether anything is being measured here: for example, the Linux 2.2.13 write figure is somewhere near 43 Meg/s, which must be timing the transfer to the disk buffer. But this must reflect what actually happens when you use the system on an application level: so why is BSD much slower ? What advantage am I accruing with BSD ? Pipe throughput test ( number of iterations per sec whilst pipe is active ) Linux 2.0.36 70621.2 Linux 2.2.13 110108.5 Vanilla BSD 59813.8 BSD + DMA 54026.7 BSD + DMA + async 56167.0 BSD + softupdates 60054.5 Pipe-based Context Switching Linux 2.0.36 30610.1 Linux 2.2.13 32276.8 Vanilla BSD 14988.1 BSD + DMA 14259.8 BSD + DMA + async 13946.7 BSD + softupdates 14599.1 Any ideas why the BSD should be so sluggish ? Regards, Harry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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