Date: Tue, 28 Apr 1998 11:29:40 -0500 From: Doug Ledford <dledford@dialnet.net> To: Matthew Jacob <mjacob@feral.com> Cc: "Robert G. Brown" <rgb@phy.duke.edu>, Mail Receiver <rmail@ittc.ukans.edu>, aic7xxx@FreeBSD.ORG, linux-smp@vger.rutgers.edu, linux-tulip@cesdis1.gsfc.nasa.gov Subject: Re: Duration of Blocked Interrupts Message-ID: <354603F4.A3218543@dialnet.net> References: <Pine.LNX.3.96.980428113454.23254G-100000@ganesh.phy.duke.edu> <3545FDE9.3710DBCD@feral.com>
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Matthew Jacob wrote:
>
> Yes, this might be true. The only problem here is that in
> looking over the version of the linux AIC stuff I have,
> it *does* go to the effort to restore_flags in a number
> of places so it doesn't lock out *everyone* for long periods
> of time. That is, it locks out all interrupts briefly
> (mostly to mark that it's servicing an interrupt), and
> then it runs a while w/o. It blocks interrupts checking
> for sequencer conditions (usually error cases), and also
> while cleaning up after finishing. It then unblocks
> interrupts before calling the linux midlayer to complete
> (well done, actually).
>
> By "blocking/unblocking" I mean higher level interrupts.
> I could easily believe that if your network cards are
> at lower or same irqs they might starve. But short
> of doing some more clever thread managment, or doing
> an explicit sti() in the SCSI midlayer, I doubt that this
> is easily fixable.
I did change that in the later versions of my code. For 2.1.x, it is
specifically required that we *don't* enable interrupts during completion
processing. I could put it back for 2.0.x, but it would create a few
questions on my part until I've had time to fully verify everything does
what it's suppossed to do.
--
Doug Ledford <dledford@dialnet.net>
Opinions expressed are my own, but
they should be everybody's.
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