Date: Sat, 9 Oct 1999 16:24:00 -0600 (MDT) From: "Kenneth D. Merry" <ken@kdm.org> To: rjesup@wgate.com (Randell Jesup) Cc: hackers@FreeBSD.ORG Subject: Re: CAM-ification - documentation Message-ID: <199910092224.QAA09485@panzer.kdm.org> In-Reply-To: <ybuzoxs33gp.fsf@jesup.eng.tvol.net.jesup.eng.tvol.net> from Randell Jesup at "Oct 9, 1999 04:26:30 pm"
next in thread | previous in thread | raw e-mail | index | archive | help
Randell Jesup wrote... > This discussion should probably move to the freebsd-scsi list... > > "Kenneth D. Merry" <ken@kdm.org> 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
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199910092224.QAA09485>