From mboxrd@z Thu Jan 1 00:00:00 1970 From: William Lee Irwin III Date: Mon, 22 Nov 2004 22:43:33 +0000 Subject: Re: page fault scalability patch V11 [0/7]: overview Message-Id: <20041122224333.GI2714@holomorphy.com> List-Id: References: <20041120062341.GM2714@holomorphy.com> <419EE911.20205@yahoo.com.au> <20041119225701.0279f846.akpm@osdl.org> <419EEE7F.3070509@yahoo.com.au> <1834180000.1100969975@[10.10.2.4]> <20041120190818.GX2714@holomorphy.com> <20041120193325.GZ2714@holomorphy.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Christoph Lameter Cc: Linus Torvalds , Nick Piggin , Andrew Morton , benh@kernel.crashing.org, hugh@veritas.com, linux-mm@kvack.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org On Sat, 20 Nov 2004, William Lee Irwin III wrote: >> I'm not particularly "stuck on" the per-cpu business, it was merely the >> most obvious method of splitting the RSS counter without catastrophes >> elsewhere. Robin Holt's 2.4 performance studies actually show that >> splitting the counter is not even essential. On Mon, Nov 22, 2004 at 09:44:02AM -0800, Christoph Lameter wrote: > There is no problem moving back to the atomic approach that is if it is > okay to also make anon_rss atomic. But its a pretty significant > performance hit (comparison with some old data from V4 of patch which > makes this data a bit suspect since the test environment is likely > slightly different. I should really test this again. Note that the old > performance test was only run 3 times instead of 10): > atomic vs. sloppy rss performance 64G allocation: The specific patches you compared matter a great deal as there are implementation blunders (e.g. poor placement of counters relative to ->mmap_sem) that can ruin the results. URL's to the specific patches would rule out that source of error. -- wli