Date: Mon, 16 Aug 2010 00:30:24 +0200 From: Roland Smith <rsmith@xs4all.nl> To: Kevin Oberman <oberman@es.net> Cc: stable@freebsd.org Subject: Re: Inconsistent IO performance Message-ID: <20100815223024.GA38722@slackbox.erewhon.net> In-Reply-To: <20100815193703.DA6461CC3A@ptavv.es.net> References: <20100814220740.GA64697@slackbox.erewhon.net> <20100815193703.DA6461CC3A@ptavv.es.net>
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--yrj/dFKFPuw6o+aM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Aug 15, 2010 at 12:37:03PM -0700, Kevin Oberman wrote: > OK. It's pretty clear that disk IO is terrible on this system. I suspect > it's the SATA/PATA converter that is the throttle. In any case, <snip> > I still have no explanation for the variation. It's not vibration. Some > of my best times were while the system was sitting in my trunk while > commuting from my home to work. So have some of the worst. If the performance is craptastic due to the SATA/PATA convertor, could that also not be a good explanation for the variation? With the different speeds= on the two busses, there might well be variation between the time it takes for commands to get through (altough one would expect that to even out over tim= e). Of course to test that you'd have to hook up a harddisk that doesn't need t= he convertor... If that improves the situation, you've found the problem. > I can only hope that my next laptop, which should have ACHI, will improve > the situation. I'll probably be getting a new laptop in the spring, so > it won't be too long. Almost time to start trying to figure out what to > buy.=20 Well, looking at my laptop's figures, it is possible to get good throughput. If you get a system with ICH9 chipset (so you can use ahci(4)), and a 7200 RPM harddisk, and you should be able to reproduce my figures, I think. Roland --=20 R.F.Smith http://www.xs4all.nl/~rsmith/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725) --yrj/dFKFPuw6o+aM Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (FreeBSD) iEYEARECAAYFAkxoaoAACgkQEnfvsMMhpyXwGQCePhFfk8MSj3SpJOT4df8hQ7wl WUQAnjhvQCTJgAyXQYnD5Pl+PqiGZB/Y =jJdi -----END PGP SIGNATURE----- --yrj/dFKFPuw6o+aM--
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