Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751083AbVLVXxy (ORCPT ); Thu, 22 Dec 2005 18:53:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751094AbVLVXxy (ORCPT ); Thu, 22 Dec 2005 18:53:54 -0500 Received: from xenotime.net ([66.160.160.81]:6576 "HELO xenotime.net") by vger.kernel.org with SMTP id S1751083AbVLVXxy (ORCPT ); Thu, 22 Dec 2005 18:53:54 -0500 Date: Thu, 22 Dec 2005 15:53:52 -0800 (PST) From: "Randy.Dunlap" X-X-Sender: rddunlap@shark.he.net To: Sean cc: Christoph Hellwig , Andrew Morton , Alan Cox , arjan@infradead.org, mingo@elte.hu, linux-kernel@vger.kernel.org, torvalds@osdl.org, arjanv@infradead.org, nico@cam.org, jes@trained-monkey.org, zwane@arm.linux.org.uk, oleg@tv-sign.ru, dhowells@redhat.com, bcrl@kvack.org, rostedt@goodmis.org, ak@suse.de, rmk+lkml@arm.linux.org.uk Subject: Re: [patch 0/9] mutex subsystem, -V4 In-Reply-To: Message-ID: References: <20051222114147.GA18878@elte.hu> <20051222035443.19a4b24e.akpm@osdl.org> <20051222122011.GA20789@elte.hu> <20051222050701.41b308f9.akpm@osdl.org> <1135257829.2940.19.camel@laptopd505.fenrus.org> <20051222054413.c1789c43.akpm@osdl.org> <1135260709.10383.42.camel@localhost.localdomain> <20051222153014.22f07e60.akpm@osdl.org> <20051222233416.GA14182@infradead.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1863 Lines: 47 On Thu, 22 Dec 2005, Sean wrote: > On Thu, December 22, 2005 6:34 pm, Christoph Hellwig said: > > On Thu, Dec 22, 2005 at 03:30:14PM -0800, Andrew Morton wrote: > >> No it does not. > >> > >> Ingo's work has shown us two things: > >> > >> a) semaphores use more kernel text than they should and > >> > >> b) semaphores are less efficient than they could be. > >> > >> Fine. Let's update the semaphore implementation to fix those things. > >> Nobody has addressed this code in several years. If we conclusively > >> cannot > >> fix these things then that's the time to start looking at implementing > >> new > >> locking mechanisms. > > > > c) semaphores are total overkill for 99% percent of the users. Remember > > this thing about optimizing for the common case? > > > > Pretty much everywhere we do want mutex semantic. So let's have a proper > > primitive exactly for that, and we can keep the current semaphore > > implementation (with a much simpler implementation) for that handfull of > > users in the kernel that really want a counting semaphore. > > > > I really don't get why you hate mutex primitives so much. > > > > Yes it's hard to figure. It seems to be deeper than just hating mutex > primitives, he hates the timer core updates that come from Ingo too; this > may be a general dislike for all things -rt. Andrew can surely answer that, but it could be something as simple as wanting to build a more stable kernel (one without so much churn), so that things have time to mature and improve without breaking so many other things... This (current) is a hectic development cycle style. -- ~Randy - 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/