Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932498AbWBUSeB (ORCPT ); Tue, 21 Feb 2006 13:34:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932468AbWBUSeB (ORCPT ); Tue, 21 Feb 2006 13:34:01 -0500 Received: from omx1-ext.sgi.com ([192.48.179.11]:31424 "EHLO omx1.americas.sgi.com") by vger.kernel.org with ESMTP id S932387AbWBUSeA (ORCPT ); Tue, 21 Feb 2006 13:34:00 -0500 Date: Tue, 21 Feb 2006 10:33:44 -0800 (PST) From: Christoph Lameter To: Nick Piggin cc: Ravikiran G Thirumalai , Andrew Morton , linux-kernel@vger.kernel.org, "Shai Fultheim (Shai@scalex86.org)" Subject: Re: [patch] Cache align futex hash buckets In-Reply-To: <43FA8938.70006@yahoo.com.au> Message-ID: References: <20060220233242.GC3594@localhost.localdomain> <43FA8938.70006@yahoo.com.au> 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: 789 Lines: 19 On Tue, 21 Feb 2006, Nick Piggin wrote: > Ravikiran G Thirumalai wrote: > > Following change places each element of the futex_queues hashtable on a > > different cacheline. Spinlocks of adjacent hash buckets lie on the same > > cacheline otherwise. > > > > It does not make sense to add swaths of unused memory into a hashtable for > this purpose, does it? It does if you essentially have a 4k cacheline (because you are doing NUMA in software with multiple PCs....) and transferring control of that cacheline is comparatively expensive. - 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/