Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757709Ab1E3SoT (ORCPT ); Mon, 30 May 2011 14:44:19 -0400 Received: from lennier.cc.vt.edu ([198.82.162.213]:57078 "EHLO lennier.cc.vt.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751757Ab1E3SoR (ORCPT ); Mon, 30 May 2011 14:44:17 -0400 X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.3-dev To: "D. Jansen" Cc: david@lang.hm, Theodore Tso , Oliver Neukum , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Dave Chinner , njs@pobox.com, bart@samwel.tk Subject: Re: [rfc] Ignore Fsync Calls in Laptop_Mode In-Reply-To: Your message of "Mon, 30 May 2011 20:28:24 +0200." From: Valdis.Kletnieks@vt.edu References: <201105231012.06928.oneukum@suse.de> <20110525000003.GJ32466@dastard> <201105250850.12179.oneukum@suse.de> <410B37BE-E380-40D0-82AA-48B56F389E16@mit.edu> <20110526133155.GH9520@thunk.org> <20110526162138.GN9520@thunk.org> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1306781002_2897P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Mon, 30 May 2011 14:43:22 -0400 Message-ID: <14586.1306781002@turing-police.cc.vt.edu> X-Mirapoint-Received-SPF: 198.82.161.152 auth3.smtp.vt.edu Valdis.Kletnieks@vt.edu 2 pass X-Mirapoint-IP-Reputation: reputation=neutral-1, source=Fixed, refid=n/a, actions=MAILHURDLE SPF TAG X-Junkmail-Status: score=10/50, host=zidane.cc.vt.edu X-Junkmail-Signature-Raw: score=unknown, refid=str=0001.0A020201.4DE3E54C.0099,ss=1,fgs=0, ip=0.0.0.0, so=2010-07-22 22:03:31, dmn=2009-09-10 00:05:08, mode=single engine X-Junkmail-IWF: false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1826 Lines: 53 --==_Exmh_1306781002_2897P Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable On Mon, 30 May 2011 20:28:24 +0200, =22D. Jansen=22 said: > I'm not really sure I why shouldn't have that choice as a user. Just > because someone else could be running a mailserver on his system and > configure it in a way that it doesn't behave as it should? It cuts both ways. If a piece of software really wants to be sure that t= he fsync() semantics it's expecting are actually adhered to and refuses to r= un otherwise, how does it tell that you're lying to it? > The big problem is that so far only fsync existed and lots of software > seemingly abuses it as an expensive write barrier. And it would really > be lovely to have the choice to stop that on an opt-in basis in laptop > mode. It's not =22seemingly abuses it=22. That's the existing userspace API fo= r inserting a barrier. The problem is that as defined, it will wait for th= e writeback to actually finish - which is actually as good as you can get w= ithout getting into the async I/O support. If there was a =22insert barrier and= return=22 API, how would it report back that the barrier had failed with EIO after = it had already returned to userspace? --==_Exmh_1306781002_2897P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFN4+VKcC3lWbTT17ARArJKAKCrsQ1jDb6VxyioLsP5tL3enKCQjwCgq54n EjDcQXxdUh+9WtZgz44kqus= =uSsg -----END PGP SIGNATURE----- --==_Exmh_1306781002_2897P-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/