Subject: Re: Low AAC performance but only when tested through the file system
To: Greg 'groggy' Lehey <grog@NetBSD.org>
From: Thor Lancelot Simon <email@example.com>
Date: 12/03/2003 01:36:38
On Wed, Dec 03, 2003 at 01:43:30PM +1030, Greg 'groggy' Lehey wrote:
> On Thursday, 27 November 2003 at 18:02:52 +0100, Olaf Seibert wrote:
> > However, when I test with a benchmark called RawIO (see
> > http://www.acnc.com/benchmarks.html) on the (unused) raw swap partition,
> > I get much better results. Sequential writing is around 35M/sec, and the
> > number of xfers/sec is over 1000, peaking at some 1900.
> This is surprisingly high. You can assume that you're not getting
> valid results.
Uh, that's nonsense. I have several PCI RAID controllers that can
deliver at least that level of performance; one of them is almost four
years old. The card in cvs.netbsd.org, which is identical to the one
Olaf has, performs about as well as he's reporting -- the difference,
though, is that we're not seeing the performance degradation through
the filesystem that he is. The reason for that is something I haven't
managed to figure out, unfortunately.