Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261184AbUKVWvS (ORCPT ); Mon, 22 Nov 2004 17:51:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261179AbUKVWs7 (ORCPT ); Mon, 22 Nov 2004 17:48:59 -0500 Received: from omx3-ext.sgi.com ([192.48.171.20]:450 "EHLO omx3.sgi.com") by vger.kernel.org with ESMTP id S261177AbUKVWsg (ORCPT ); Mon, 22 Nov 2004 17:48:36 -0500 Date: Mon, 22 Nov 2004 14:48:22 -0800 (PST) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Andrew Morton cc: hugh@veritas.com, torvalds@osdl.org, benh@kernel.crashing.org, nickpiggin@yahoo.com.au, linux-mm@kvack.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: deferred rss update instead of sloppy rss In-Reply-To: <20041122144507.484a7627.akpm@osdl.org> Message-ID: References: <20041122141148.1e6ef125.akpm@osdl.org> <20041122144507.484a7627.akpm@osdl.org> 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: 983 Lines: 23 On Mon, 22 Nov 2004, Andrew Morton wrote: > > The page fault code only increments rss. For larger transactions that > > increase / decrease rss significantly the page_table_lock is taken and > > mm->rss is updated directly. So no > > gross inaccuracies can result. > > Sure. Take a million successive pagefaults and mm->rss is grossly > inaccurate. Hence my suggestion that it be spilled into mm->rss > periodically. It is spilled into mm->rss periodically. That is the whole point of the patch. The timer tick occurs every 1 ms. The maximum pagefault frequency that I have seen is 500000 faults /second. The max deviation is therefore less than 500 (could be greater if page table lock / mmap_sem always held when the tick occurs). - 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/