Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965248AbWH2SbY (ORCPT ); Tue, 29 Aug 2006 14:31:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965246AbWH2SbY (ORCPT ); Tue, 29 Aug 2006 14:31:24 -0400 Received: from mx1.redhat.com ([66.187.233.31]:23690 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S965203AbWH2SbW (ORCPT ); Tue, 29 Aug 2006 14:31:22 -0400 From: David Howells In-Reply-To: <200608292018.01602.ak@suse.de> References: <200608292018.01602.ak@suse.de> <44F395DE.10804@yahoo.com.au> <200608291922.04354.ak@suse.de> To: Andi Kleen Cc: Christoph Lameter , David Howells , Nick Piggin , Arjan van de Ven , Dong Feng , Paul Mackerras , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: Why Semaphore Hardware-Dependent? X-Mailer: MH-E 8.0; nmh 1.1; GNU Emacs 22.0.50 Date: Tue, 29 Aug 2006 19:30:59 +0100 Message-ID: <809.1156876259@warthog.cambridge.redhat.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 678 Lines: 16 Andi Kleen wrote: > BTW maybe it would be a good idea to switch the wait list to a hlist, > then the last user in the queue wouldn't need to > touch the cache line of the head. Or maybe even a single linked > list then some more cache bounces might be avoidable. You need a list_head to get O(1) push at one end and O(1) pop at the other. In addition a singly-linked list makes interruptible ops non-O(1) also. David - 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/