Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753855AbZAFNVZ (ORCPT ); Tue, 6 Jan 2009 08:21:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753384AbZAFNVF (ORCPT ); Tue, 6 Jan 2009 08:21:05 -0500 Received: from casper.infradead.org ([85.118.1.10]:46707 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753228AbZAFNVC (ORCPT ); Tue, 6 Jan 2009 08:21:02 -0500 Subject: Re: [PATCH][RFC]: mutex: adaptive spin From: Peter Zijlstra To: Ingo Molnar Cc: Gregory Haskins , Matthew Wilcox , Andi Kleen , Chris Mason , Andrew Morton , linux-kernel@vger.kernel.org, linux-fsdevel , linux-btrfs , Thomas Gleixner , Steven Rostedt , Nick Piggin , Linus Torvalds In-Reply-To: <20090106131643.GA15228@elte.hu> References: <1230722935.4680.5.camel@think.oraclecorp.com> <20081231104533.abfb1cf9.akpm@linux-foundation.org> <1230765549.7538.8.camel@think.oraclecorp.com> <87r63ljzox.fsf@basil.nowhere.org> <20090103191706.GA2002@parisc-linux.org> <1231093310.27690.5.camel@twins> <20090104184103.GE2002@parisc-linux.org> <1231242031.11687.97.camel@twins> <20090106121052.GA27232@elte.hu> <4963584A.4090805@novell.com> <20090106131643.GA15228@elte.hu> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Tue, 06 Jan 2009 14:20:41 +0100 Message-Id: <1231248041.11687.107.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.24.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1372 Lines: 28 On Tue, 2009-01-06 at 14:16 +0100, Ingo Molnar wrote: > * Gregory Haskins wrote: > > > Ingo Molnar wrote: > > > There's no time or spin-rate based heuristics in this at all (i.e. these > > > mutexes are not 'adaptive' at all!), > > > > FYI: The original "adaptive" name was chosen in the -rt implementation > > to reflect that the locks can adaptively spin or sleep, depending on > > conditions. I realize this is in contrast to the typical usage of the > > term when it is in reference to the spin-time being based on some > > empirical heuristics, etc as you mentioned. Sorry for the confusion. > > the current version of the -rt spinny-mutexes bits were mostly written by > Steve, right? Historically it all started out with a more classic > "adaptive mutexes" patchset so the name stuck i guess. Yeah, Gregory and co. started with the whole thing and showed there was significant performance to be gained, after that Steve rewrote it from scratch reducing it to this minimalist heuristic, with help from Greg. (At least, that is how I remember it, please speak up if I got things wrong) -- 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/