From owner-freebsd-hackers Sat Oct 9 15:24:30 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from panzer.kdm.org (panzer.kdm.org [216.160.178.169]) by hub.freebsd.org (Postfix) with ESMTP id 98B7A151D0 for ; Sat, 9 Oct 1999 15:24:13 -0700 (PDT) (envelope-from ken@panzer.kdm.org) Received: (from ken@localhost) by panzer.kdm.org (8.9.3/8.9.1) id QAA09485; Sat, 9 Oct 1999 16:24:00 -0600 (MDT) (envelope-from ken) Message-Id: <199910092224.QAA09485@panzer.kdm.org> Subject: Re: CAM-ification - documentation In-Reply-To: from Randell Jesup at "Oct 9, 1999 04:26:30 pm" To: rjesup@wgate.com (Randell Jesup) Date: Sat, 9 Oct 1999 16:24:00 -0600 (MDT) Cc: hackers@FreeBSD.ORG From: "Kenneth D. Merry" X-Mailer: ELM [version 2.4ME+ PL54 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Randell Jesup wrote... > This discussion should probably move to the freebsd-scsi list... > > "Kenneth D. Merry" writes: > >Nick Hibma wrote... > >> Especially some help on the topic of polling would be appreciated. > >> Otherwise I'll have to resort to figuring out how to do things in > >> interrupt context, and that is going to be dirty. > > >If you're talking about polling for transaction completion in a device > >driver, my guess is that you're going to have to do things in an interrupt > >context. (Unless you use a kernel process to do it.) > > > >The thing to remember is that when you get CCBs down in a CAM device > >driver, it may well be in an interrupt context. You have to be able to > >deal with that. My guess is that it might be easiest to just use a timeout > >handler to poll the device for completion every so often. A kernel process > >may also be an option, depending on how nasty the device is. > > Ick. Polling == bad. Interrupts == good. This isn't a single- > tasking OS ala Win9x. This goes double for SCSI drivers, which are > inherently async and overlapped. I never said polling was good. Nick just asked about polling, and I commented on how it could be done. I have no idea why he wanted to know about polling, though. Ken -- Kenneth Merry ken@kdm.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message