Date: Sat, 15 Aug 1998 13:28:21 +0000 From: Mike Smith <mike@word.smith.net.au> To: Terry Lambert <tlambert@primenet.com> Cc: mike@smith.net.au (Mike Smith), thorpej@nas.nasa.gov, hackers@FreeBSD.ORG Subject: Re: TESTERS WANTED for new ATAPI CD/CDR/CDRW driver. Message-ID: <199808151328.NAA01756@word.smith.net.au> In-Reply-To: Your message of "Sat, 15 Aug 1998 20:23:15 GMT." <199808152023.NAA20511@usr01.primenet.com>
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> > I'd be curious to know if anyone's measured the cost of the SCSI<->ATA > > translation for ATA disks, since that's where performance is really an > > issue. Nobody cares how efficient access to a Zip disk is, but an > > extra 10% overhead on ATA disk transactions would really hurt. > > > > Command passthrough doesn't (can't) work directly, as many fields are > > different sizes. I think what you mean is that there's no need for any > > intelligence in the translation, which is fair enough. > > A question I have is this: > > If I'm passing SCSI commands down, is it possible to actually support > multiple outstanding tagged commands? At the level you're passing commands down, you don't care (or know) whether they're going to be tagged and/or executed in parallel. > I know that the EIDE specification allows for this, but I am unaware > of any IDE disk drives that support it. You are confusing ATAPI (where SCSI passthrough is worthwhile) and ATA (where it may not be). EIDE is a non-term. -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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