From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 12 Jan 2005 09:37:27 -0800 (PST) From: Christoph Lameter Subject: Re: page table lock patch V15 [0/7]: overview In-Reply-To: <20050112164906.GA4935@infradead.org> Message-ID: References: <41E4BCBE.2010001@yahoo.com.au> <20050112014235.7095dcf4.akpm@osdl.org> <20050112164906.GA4935@infradead.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Hellwig Cc: Andrew Morton , Nick Piggin , 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 List-ID: On Wed, 12 Jan 2005, Christoph Hellwig wrote: > On Wed, Jan 12, 2005 at 08:39:21AM -0800, Christoph Lameter wrote: > > The future is in higher and higher SMP counts since the chase for the > > higher clock frequency has ended. We will increasingly see multi-core > > cpus etc. Machines with higher CPU counts are becoming common in business. > > An they still are absolutely in the minority. In fact with multicore > cpus it becomes more and more important to be fast for SMP systtems with > a _small_ number of CPUs, while really larget CPUs will remain a small > nische for the forseeable future. The benefits start to be significant pretty fast with even a few cpus on modern architectures: Altix no patch: Gb Rep Threads User System Wall flt/cpu/s fault/wsec 1 10 1 0.107s 6.444s 6.055s100028.084 100006.622 1 10 2 0.121s 9.048s 4.082s 71468.414 135904.412 1 10 4 0.129s 10.185s 3.011s 63531.985 210146.600 w/patch Gb Rep Threads User System Wall flt/cpu/s fault/wsec 1 10 1 0.094s 6.116s 6.021s105517.039 105517.574 1 10 2 0.134s 6.998s 3.087s 91879.573 169079.712 1 10 4 0.095s 7.658s 2.043s 84519.939 268955.165 There is even a small benefit to the single thread case. Its not the case that this patch only benefits systems with a large number of CPUs. Of course that is when the benefits results in performance gains by orders of magnitude. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org