Date: Tue, 13 Jun 2000 19:33:03 +0200 (CEST) From: =?ISO-8859-1?Q?G=E9rard_Roudier?= <groudier@club-internet.fr> To: "Kenneth D. Merry" <ken@kdm.org> Cc: Todd Cohen <cohentl@clarkson.edu>, freebsd-stable@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG Subject: Re: Problem with newer sym driver on a Tekram DC-390U2W controller Message-ID: <Pine.LNX.4.10.10006131915100.461-100000@linux.local> In-Reply-To: <20000613103825.A24786@panzer.kdm.org>
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On Tue, 13 Jun 2000, Kenneth D. Merry wrote: > On Tue, Jun 13, 2000 at 12:16:59 -0400, Todd Cohen wrote: > > Different but related question, are the DC-315U cards supported? > > If you use Tekram's driver, yes. > > Those cards, as well as their DC-395 series cards are based on Tekram's own > S1040 chip. > > >From the driver, though, it appears that the card doesn't have a SCSI phase > engine, so there will be multiple interrupts per transaction. And it appears that some non negligible amount of IOs through the PCI BUS is to be performed for each interrupt. When the BUS is busy, this may result in the CPU being stalled uselessly for micro-seconds (equivalent to thousands of instructions lost given modern CPUs). Under an O/S or a system that is either doing one thing at time or nothing most of the time, this probably does not make significant difference. But under a UNIX O/S, this probably is a significant penalty compared to SYMBIOS chips (given an appropriate software driver that takes advantage of SYMBIOS chips capabilities). Price difference between Tekram 3X5 and SCSI mode equivalent but PCI far superior Tekram 390-X controllers seems low-enough for me to claim that purchasing a 390-X is a far better buy. If we take into account the price of SCSI devices, then bying a 3X5 boards seems just stupid to me. > You would probably be beter off getting one of their Symbios/LSI based > boards. Indeed. Gerard. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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