From owner-aic7xxx  Tue Apr 28 09:07:06 1998
Return-Path: <owner-aic7xxx@FreeBSD.ORG>
Received: (from majordom@localhost)
          by hub.freebsd.org (8.8.8/8.8.8) id JAA23458
          for aic7xxx-outgoing; Tue, 28 Apr 1998 09:07:06 -0700 (PDT)
          (envelope-from owner-aic7xxx@FreeBSD.ORG)
Received: from feral.com (root@[209.54.254.2])
          by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id JAA23400
          for <aic7xxx@FreeBSD.ORG>; Tue, 28 Apr 1998 09:06:59 -0700 (PDT)
          (envelope-from mjacob@feral.com)
Received: from feral-gw (mjacob@gw100.feral.com [192.67.166.129])
	by feral.com (8.8.6/8.8.6) with SMTP id JAA00786;
	Tue, 28 Apr 1998 09:03:53 -0700
Message-ID: <3545FDE9.3710DBCD@feral.com>
Date: Tue, 28 Apr 1998 09:03:53 -0700
From: Matthew Jacob <mjacob@feral.com>
Organization: Feral Software
X-Mailer: Mozilla 3.04 (X11; I; Linux 2.0.33 i586)
MIME-Version: 1.0
To: "Robert G. Brown" <rgb@phy.duke.edu>
CC: 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
References: <Pine.LNX.3.96.980428113454.23254G-100000@ganesh.phy.duke.edu>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Sender: owner-aic7xxx@FreeBSD.ORG
Precedence: bulk

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.

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe aic7xxx" in the body of the message