Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030375AbVLVXeW (ORCPT ); Thu, 22 Dec 2005 18:34:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030377AbVLVXeW (ORCPT ); Thu, 22 Dec 2005 18:34:22 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:38837 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S1030375AbVLVXeV (ORCPT ); Thu, 22 Dec 2005 18:34:21 -0500 Date: Thu, 22 Dec 2005 23:34:16 +0000 From: Christoph Hellwig To: Andrew Morton Cc: 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, hch@infradead.org, ak@suse.de, rmk+lkml@arm.linux.org.uk Subject: Re: [patch 0/9] mutex subsystem, -V4 Message-ID: <20051222233416.GA14182@infradead.org> Mail-Followup-To: 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 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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051222153014.22f07e60.akpm@osdl.org> User-Agent: Mutt/1.4.2.1i X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1194 Lines: 28 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. - 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/