Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755362AbZAHD5Z (ORCPT ); Wed, 7 Jan 2009 22:57:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751533AbZAHD5Q (ORCPT ); Wed, 7 Jan 2009 22:57:16 -0500 Received: from victor.provo.novell.com ([137.65.250.26]:50997 "EHLO victor.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750873AbZAHD5P (ORCPT ); Wed, 7 Jan 2009 22:57:15 -0500 Message-ID: <49657A52.2050702@novell.com> Date: Wed, 07 Jan 2009 23:00:18 -0500 From: Gregory Haskins User-Agent: Thunderbird 2.0.0.18 (X11/20081112) MIME-Version: 1.0 To: Steven Rostedt CC: Linus Torvalds , Andi Kleen , Matthew Wilcox , Peter Zijlstra , paulmck@linux.vnet.ibm.com, Ingo Molnar , Chris Mason , Andrew Morton , Linux Kernel Mailing List , linux-fsdevel , linux-btrfs , Thomas Gleixner , Nick Piggin , Peter Morreale , Sven Dietrich Subject: Re: [PATCH -v5][RFC]: mutex: implement adaptive spinning References: <1231281801.11687.125.camel@twins> <1231283778.11687.136.camel@twins> <1231329783.11687.287.camel@twins> <1231347442.11687.344.camel@twins> <20090107210923.GV2002@parisc-linux.org> <20090107213924.GP496@one.firstfloor.org> <49652C7C.3000909@novell.com> <49657297.9000708@novell.com> In-Reply-To: X-Enigmail-Version: 0.95.7 OpenPGP: id=D8195319 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig5BEF5657D0E5E6EDEBEE4C8F" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2318 Lines: 62 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig5BEF5657D0E5E6EDEBEE4C8F Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Steven Rostedt wrote: > On Wed, 7 Jan 2009, Gregory Haskins wrote: > =20 >> In my defense, the -rt versions of the patches guarantee this is ok >> based on a little hack: >> =20 > > The -rt versions worry about much more than what the mutex code in > mainline does. Linus is correct in his arguments. The adaptive mutex (a= s=20 > suppose to what -rt has), is only to help aid in preformance. There are= a=20 > lot of races that can happen in mainline version where lock taking may = not=20 > be fifo, or where we might start to schedule when we could have taken t= he=20 > lock. These races are not in -rt, but that is because -rt cares about=20 > these. But mainline cares more about performance over determinism. This= =20 > means that we have to look at the current code that Peter is submitting= =20 > with a different perspective than we do in -rt. > =20 Hey Steve, Understood, and agreed. I only mentioned it because I wanted to clear the record that I did not (to my knowledge) mess up the protocol design which first introduced the get/put-task pattern under discussion ;). I am fairly confident that at least the -rt version does not have any race conditions such as the one Linus mentioned in the mainline version. I am not advocating that the full protocol that we use in -rt should be carried forward, per se or anything like that. -Greg --------------enig5BEF5657D0E5E6EDEBEE4C8F Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAkllelIACgkQlOSOBdgZUxncEACeLmAFfg1k0t4QyWETbrWKJ3S8 nLUAnjftloyOFW7JhKpsVDSp+0prZDgc =wGal -----END PGP SIGNATURE----- --------------enig5BEF5657D0E5E6EDEBEE4C8F-- -- 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/