Date: Thu, 9 Jan 1997 16:42:36 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: phk@critter.dk.tfs.com (Poul-Henning Kamp) Cc: mef@cs.washington.edu, smp@freebsd.org Subject: Re: unusual question Message-ID: <199701092342.QAA18917@phaeton.artisoft.com> In-Reply-To: <7514.852822663@critter.dk.tfs.com> from "Poul-Henning Kamp" at Jan 9, 97 04:11:03 pm
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> Generally, you can allow device-drivers to be multi-threaded only as > far as you have separate pieces of hardware. Ie, in you average > FreeBSD system you could have one thread/cpu per sio port, but only > one for wdc0+wd0+wd1 because they share registers. > > I would expect the "one-lock per device-driver" to be implemented > in the code that calls into the device drivers, simply to avoid > changing all of them, so most device-drivers will probably not > change much if at all. Initially, anyway. Ideally, there would be top/bottom based drivers to implement code for running above and below a HAL; this would ensure maximum concurrency (mostly a problem for SCSI controllers; most other things won't care, but it's the principle of the thing... Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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