From owner-freebsd-current  Tue Apr 16 18:42:45 2002
Delivered-To: freebsd-current@freebsd.org
Received: from harrier.prod.itd.earthlink.net (harrier.mail.pas.earthlink.net [207.217.120.12])
	by hub.freebsd.org (Postfix) with ESMTP
	id 37CA437B405; Tue, 16 Apr 2002 18:42:38 -0700 (PDT)
Received: from pool0108.cvx40-bradley.dialup.earthlink.net ([216.244.42.108] helo=mindspring.com)
	by harrier.prod.itd.earthlink.net with esmtp (Exim 3.33 #1)
	id 16xeSy-0000Ry-00; Tue, 16 Apr 2002 18:42:37 -0700
Message-ID: <3CBCD2F1.3A1A823F@mindspring.com>
Date: Tue, 16 Apr 2002 18:42:09 -0700
From: Terry Lambert <tlambert2@mindspring.com>
X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony}  (Win98; U)
X-Accept-Language: en
MIME-Version: 1.0
To: John Baldwin <jhb@FreeBSD.org>
Cc: freebsd-current@freebsd.org, msch@snafu.de
Subject: Re: ATA errors on recent -current
References: <XFMail.20020416212755.jhb@FreeBSD.org>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Sender: owner-freebsd-current@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-current.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-current>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-current>
X-Loop: FreeBSD.ORG

John Baldwin wrote:
> > My hunch, which is why I suggested decreasing the number of
> > tags seen by the driver, is that the tagged queues are over
> > used, and this locks the disk up.  My best guess is an off-by-one
> > or an exceptional condition handler that was not an issue until
> > recently, because of a FreeBSD interrupt architecture change
> > having nothing to do with the driver itself (i.e. the reason it
> > only happens under load, and didn't happen under the same load,
> > before).
> 
> Terry, we've had threaded interrupt handlers for over a year and a half
> now.  If the had really broken things in this basic a fashion we wouldn't
> have made it this far with running systems.  Your hypothesis about
> something busted in the tagged queueing code seems sound but blaiming
> this on interrupt threads doesn't make much sense to me.

The problems don't show up, except under extreme loads, with
particular drives.

Therefore, it is still my hunch.  ;^).

Dropping the queue depth to 8 from 16 to attempt to verify my
hunch won't hurt anything, and may find the problem.  It could
still be an off-by-one error in Soren's code, as well (but I
don't think it is).

-- Terry

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