Date: Mon, 18 Oct 2004 23:23:23 -0600 From: Scott Long <scottl@freebsd.org> To: fandino@ng.fadesa.es Cc: freebsd-current@freebsd.org Subject: Re: FreeBSD 5.3b7and poor ata performance Message-ID: <4174A4CB.3090003@freebsd.org> In-Reply-To: <4173F2E9.7010407@ng.fadesa.es> References: <20041015190638.C5A0E5D04@ptavv.es.net> <41715E7F.7060509@ng.fadesa.es> <20041018100045.f8koww0skcco0woo@www.sweetdreamsracing.biz> <4173D66F.6010200@DeepCore.dk> <4173F2E9.7010407@ng.fadesa.es>
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fandino wrote: > Hello Søren, > > Søren Schmidt wrote: > >>>> GNU/Linux 2.4.18 with ext2: 56848 K/sec >>>> FreeBSD 5.3b7 with default fs: 26347 K/sec >>>> FreeBSD 5.3b7 with default fs(async): 26566 K/sec >>>> FreeBSD 5.3b7 ata raid0* (two disks): 26131 K/sec >>>> FreeBSD 5.3b7 geom stripe* (two disks): 30063 K/sec >>>> FreeBSD 5.3b7 geom stripe** (four disks): 31891 K/sec >>>> OpenBSD 3.5 UFS fs: 55277 K/sec >>>> >>>> * Each disk of the raid had a throughput of approx. 15000 K/sec >>>> ** Each disk of the raid had a throughput of approx. 7500 K/sec >>>> Each disk of the read split the throughput by half. >>>> >>>> How is possible that FreeBSD performs as bad? >>>> >>>> >>> If you're still using the GENERIC kernel, that could explain it, and >>> judging >>> from other emails I've seen from you, you're still using the GENERIC >>> kernel. >> >> >> Right, and you should also use -U (softupdates) on you newfs line. > > > > > FreeBSD 5.3b7 with default fs(+softupdates): 26615 K/sec > http://195.55.55.164/tests/fbsd+softupdates.txt > > > > I was running FreeBSD-4.x for two years with this problem, waiting > for FreeBSD-5 because ATAng looks very promising. > > Unfortunately the performance problem persist :-( and I'd like to > call the attention about performance over raw devices, whilst it's > a very scientific test it's very curious: > > # dd if=/dev/ad4 of=/dev/null bs=1024k count=1024 > 1024+0 records in > 1024+0 records out > 1073741824 bytes transferred in 31.090536 secs (34535970 bytes/sec) > > over 34000 K/sec, using raw devices (for sequential access obviously) > not softupdates, filesystems or caches are involved, and with all this > FreeBSD performace is very deficient. Tests with OpenBSD and Linux > using raw devices shows a throughput of approx 60000 K/sec. > The question here is why using low-level access to disks is so bad? > > Perphas I'm missing something but this seems very weird to me. > > I'd like to know wich is you opinion about this. > > Thank you. After you run your test, can you send the output of 'sysctl hw.busdma'? Thanks, Scott
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