Date: Sun, 17 Apr 2005 22:23:14 -0700 From: Mike Smith <msmith@mu.org> To: Mikhail Teterin <mi@corbulon.video-collage.com> Cc: trhodes@freebsd.org Subject: Re: speed of a ciss-based pseudo-disk Message-ID: <1CA47A90-7B13-4EFC-9E3A-4A6441353DBD@mu.org> In-Reply-To: <200504172305.j3HN53SD098019@corbulon.video-collage.com> References: <200504172305.j3HN53SD098019@corbulon.video-collage.com>
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On Apr 17, 2005, at 4:05 PM, Mikhail Teterin wrote: >> Are you asking that someone go implement a 'nominal' speed tester in >> the kernel that will accurately determine the speed of each attached >> storage device? > > Scott, I'm asking about a nominal number. If my controller can not > talk > to the attached drives at U320 and negotiates down to lower speeds, > I'd > like to know about it. There's no way to obtain a "nominal" number. The 133MHz number comes from the maximum theoretical sustained bandwidth of a 32-bit 33MHz PCI bus. Since there's no good way in the driver to detect the bus width, or any way to determine the negotiated speed for a given drive, I'm afraid you're SOL. > If, as Paul Saab responded, even the nominal number is unobtainable > for > HP/Compaq arrays -- fine. The driver's output confused me, so I asked > about its meaning. CAM insists on having a number. I gave it a number: 2587: cpi->base_transfer_speed = 132 * 1024; /* XXX what to set this to? */ = Mike
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