From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932178AbVLMNXq (ORCPT ); Tue, 13 Dec 2005 08:23:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932175AbVLMNXq (ORCPT ); Tue, 13 Dec 2005 08:23:46 -0500 Received: from mail1.kontent.de ([81.88.34.36]:23964 "EHLO Mail1.KONTENT.De") by vger.kernel.org with ESMTP id S932163AbVLMNXp (ORCPT ); Tue, 13 Dec 2005 08:23:45 -0500 From: Oliver Neukum To: Alan Cox Subject: Re: [PATCH 1/19] MUTEX: Introduce simple mutex implementation Date: Tue, 13 Dec 2005 14:24:08 +0100 User-Agent: KMail/1.8 Cc: Ingo Molnar , David Howells , Nick Piggin , torvalds@osdl.org, akpm@osdl.org, hch@infradead.org, arjan@infradead.org, matthew@wil.cx, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org References: <439E122E.3080902@yahoo.com.au> <200512131347.30464.oliver@neukum.org> <1134479371.11732.19.camel@localhost.localdomain> In-Reply-To: <1134479371.11732.19.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200512131424.09522.oliver@neukum.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Am Dienstag, 13. Dezember 2005 14:09 schrieb Alan Cox: > On Maw, 2005-12-13 at 13:47 +0100, Oliver Neukum wrote: > > > spinlock to do the cmpxchg. This means that there wont be one single > > > global spinlock to emulate cmpxchg, but the mutex's own spinlock can be > > > used for it. > > > > Can't you use the pointer as a hash input? > > Some platforms already do this for certain sets of operations like > atomic_t. The downside however is that you no longer control the lock > contention or cache line bouncing. It becomes a question of luck rather > than science as to how well it scales. On the other hand you don't control cache eviction either, do you? Regards Oliver