From owner-freebsd-geom@FreeBSD.ORG Sun Sep 23 04:48:35 2012 Return-Path: Delivered-To: freebsd-geom@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id EA85D1065670; Sun, 23 Sep 2012 04:48:34 +0000 (UTC) (envelope-from jmg@h2.funkthat.com) Received: from h2.funkthat.com (gate2.funkthat.com [208.87.223.18]) by mx1.freebsd.org (Postfix) with ESMTP id A35658FC0C; Sun, 23 Sep 2012 04:48:34 +0000 (UTC) Received: from h2.funkthat.com (localhost [127.0.0.1]) by h2.funkthat.com (8.14.3/8.14.3) with ESMTP id q8N4mSdI014744 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sat, 22 Sep 2012 21:48:28 -0700 (PDT) (envelope-from jmg@h2.funkthat.com) Received: (from jmg@localhost) by h2.funkthat.com (8.14.3/8.14.3/Submit) id q8N4mSAB014743; Sat, 22 Sep 2012 21:48:28 -0700 (PDT) (envelope-from jmg) Date: Sat, 22 Sep 2012 21:48:28 -0700 From: John-Mark Gurney To: Pawel Jakub Dawidek Message-ID: <20120923044828.GI19036@funkthat.com> Mail-Followup-To: Pawel Jakub Dawidek , freebsd-geom@freebsd.org References: <20120919040430.GF19036@funkthat.com> <20120922162025.GE1454@garage.freebsd.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120922162025.GE1454@garage.freebsd.pl> User-Agent: Mutt/1.4.2.3i X-Operating-System: FreeBSD 7.2-RELEASE i386 X-PGP-Fingerprint: 54BA 873B 6515 3F10 9E88 9322 9CB1 8F74 6D3F A396 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ X-Resume: http://resnet.uoregon.edu/~gurney_j/resume.html X-to-the-FBI-CIA-and-NSA: HI! HOW YA DOIN? can i haz chizburger? X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.2.2 (h2.funkthat.com [127.0.0.1]); Sat, 22 Sep 2012 21:48:28 -0700 (PDT) Cc: freebsd-geom@freebsd.org Subject: Re: geli and BIO_FLUSH and/or BIO_ORDERED issue? X-BeenThere: freebsd-geom@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: GEOM-specific discussions and implementations List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 23 Sep 2012 04:48:35 -0000 Pawel Jakub Dawidek wrote this message on Sat, Sep 22, 2012 at 18:20 +0200: > On Tue, Sep 18, 2012 at 09:04:30PM -0700, John-Mark Gurney wrote: > > I was looking at geli and I'm not sure if it's implementing BIO_FLUSH > > and/or BIO_ORDERED properly... > > > > >From my understanding is the BIO_ORDERED is suppose to wait for the > > previous _WRITES to complete before returning so that you can ensure > > that data is on disk, i.e. _ORDERED is set on a BIO_FLUSH... > > > > BIO_ORDERED is handled by diskq_* code such that when you add an _ORDERED > > command, all commands are put after it, but there doesn't appear to > > be any code to ensure that an _ORDERED command waits for prevoius > > pending commands to complete.. > > > > This is extra obvious in eli in that a _FLUSH is immediately dispatched, > > even when there may be _WRITEs that haven't been finished encrypting and > > sent down to the disk to get _FLUSHed... > > > > Any comments about this? > > Hmm, BIO_ORDERED was introduced pretty recently and GEOM classes were > not updated to honour it, but it also seems to be to complex to handle > in GEOM classes. I wonder if we could hold off new writes and wait for > the in-progress writes in GEOM if we spot BIO_ORDERED request without > the need to implement this logic in GEOM classes. Yeh. When I was looking at it, it definately seems like it should be something that we provide a generic method of handling (as part of bioq_*), since all the geom classes need to handle it... It'll be a bit difficult since we'd need to introduce some syncronization between the up/down threads to start the new writes when the previous writes finish... And with a class like geli, you can get better latency if we move handling into the class though... -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."