From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751378AbVLQHNF (ORCPT ); Sat, 17 Dec 2005 02:13:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751377AbVLQHNF (ORCPT ); Sat, 17 Dec 2005 02:13:05 -0500 Received: from dsl027-180-168.sfo1.dsl.speakeasy.net ([216.27.180.168]:50320 "EHLO sunset.davemloft.net") by vger.kernel.org with ESMTP id S1751375AbVLQHND (ORCPT ); Sat, 17 Dec 2005 02:13:03 -0500 Date: Fri, 16 Dec 2005 23:10:56 -0800 (PST) Message-Id: <20051216.231056.124758189.davem@davemloft.net> To: jbarnes@virtuousgeek.org Cc: torvalds@osdl.org, dhowells@redhat.com, nickpiggin@yahoo.com.au, arjan@infradead.org, akpm@osdl.org, alan@lxorguk.ukuu.org.uk, cfriesen@nortel.com, hch@infradead.org, matthew@wil.cx, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH 1/19] MUTEX: Introduce simple mutex implementation From: "David S. Miller" In-Reply-To: <200512161641.49571.jbarnes@virtuousgeek.org> References: <20051216.145306.132052494.davem@davemloft.net> <200512161641.49571.jbarnes@virtuousgeek.org> X-Mailer: Mew version 4.2.53 on Emacs 21.4 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Jesse Barnes Date: Fri, 16 Dec 2005 16:41:49 -0800 > Note that under contention prefetching with a write bias can cause a lot > more cache line bouncing than a regular load into shared state (assuming > you do a load and test before you try the CAS). If there is some test guarding the CAS, yes. But if there isn't, for things like atomic increment and decrement, where the CAS is unconditional, you'll always eat the two bus transactions without the prefetch for write.