Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261596AbVALXvC (ORCPT ); Wed, 12 Jan 2005 18:51:02 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261597AbVALXuq (ORCPT ); Wed, 12 Jan 2005 18:50:46 -0500 Received: from smtp203.mail.sc5.yahoo.com ([216.136.129.93]:46935 "HELO smtp203.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S261596AbVALXuR (ORCPT ); Wed, 12 Jan 2005 18:50:17 -0500 Message-ID: <41E5B7AD.40304@yahoo.com.au> Date: Thu, 13 Jan 2005 10:50:05 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.3) Gecko/20041007 Debian/1.7.3-5 X-Accept-Language: en MIME-Version: 1.0 To: Andrew Morton CC: clameter@sgi.com, torvalds@osdl.org, ak@muc.de, hugh@veritas.com, linux-mm@kvack.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, benh@kernel.crashing.org Subject: Re: page table lock patch V15 [0/7]: overview References: <41E4BCBE.2010001@yahoo.com.au> <20050112014235.7095dcf4.akpm@osdl.org> <20050112104326.69b99298.akpm@osdl.org> <41E5AFE6.6000509@yahoo.com.au> <20050112153033.6e2e4c6e.akpm@osdl.org> In-Reply-To: <20050112153033.6e2e4c6e.akpm@osdl.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1039 Lines: 29 Andrew Morton wrote: > Nick Piggin wrote: > >>So my patches cost about 7% in lmbench fork benchmark. > > > OK, well that's the sort of thing we need to understand fully. What sort > of CPU was that on? > That was on a P4, although I've seen pretty similar results on ia64 and other x86 CPUs. Note that this was with my ptl removal patches. I can't see why Christoph's would have _any_ extra overhead as they are, but it looks to me like they're lacking in atomic ops. So I'd expect something similar for Christoph's when they're properly atomic. > Look, -7% on a 2-way versus +700% on a many-way might well be a tradeoff we > agree to take. But we need to fully understand all the costs and benefits. > I think copy_page_range is the one to keep an eye on. - 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/