From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 1698E6B004F for ; Tue, 19 May 2009 21:58:15 -0400 (EDT) Received: from mt1.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n4K1x7lS010877 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Wed, 20 May 2009 10:59:08 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 88DD145DE5B for ; Wed, 20 May 2009 10:59:07 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 5A6CB45DE53 for ; Wed, 20 May 2009 10:59:07 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 28C851DB803F for ; Wed, 20 May 2009 10:59:07 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.249.87.103]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 9CC73E08002 for ; Wed, 20 May 2009 10:59:06 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH 2/3] vmscan: make mapped executable pages the first class citizen In-Reply-To: <20090520014445.GA7645@localhost> References: <2f11576a0905190528n5eb29e3fme42785a76eed3551@mail.gmail.com> <20090520014445.GA7645@localhost> Message-Id: <20090520105159.743B.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Wed, 20 May 2009 10:59:05 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Wu Fengguang Cc: kosaki.motohiro@jp.fujitsu.com, Christoph Lameter , Andrew Morton , LKML , Elladan , Nick Piggin , Johannes Weiner , Peter Zijlstra , Rik van Riel , "tytso@mit.edu" , "linux-mm@kvack.org" , "minchan.kim@gmail.com" List-ID: > On Tue, May 19, 2009 at 08:28:28PM +0800, KOSAKI Motohiro wrote: > > Hi > > > > 2009/5/19 Wu Fengguang : > > > On Tue, May 19, 2009 at 04:06:35PM +0800, KOSAKI Motohiro wrote: > > >> > > > Like the console mode, the absolute nr_mapped drops considerably - to 1/13 of > > >> > > > the original size - during the streaming IO. > > >> > > > > > >> > > > The delta of pgmajfault is 3 vs 107 during IO, or 236 vs 393 during the whole > > >> > > > process. > > >> > > > > >> > > hmmm. > > >> > > > > >> > > about 100 page fault don't match Elladan's problem, I think. > > >> > > perhaps We missed any addional reproduce condition? > > >> > > > >> > Elladan's case is not the point of this test. > > >> > Elladan's IO is use-once, so probably not a caching problem at all. > > >> > > > >> > This test case is specifically devised to confirm whether this patch > > >> > works as expected. Conclusion: it is. > > >> > > >> Dejection ;-) > > >> > > >> The number should address the patch is useful or not. confirming as expected > > >> is not so great. > > > > > > OK, let's make the conclusion in this way: > > > > > > The changelog analyzed the possible beneficial situation, and this > > > test backs that theory with real numbers, ie: it successfully stops > > > major faults when the active file list is slowly scanned when there > > > are partially cache hot streaming IO. > > > > > > Another (amazing) finding of the test is, only around 1/10 mapped pages > > > are actively referenced in the absence of user activities. > > > > > > Shall we protect the remaining 9/10 inactive ones? This is a question ;-) > > > > Unfortunately, I don't reproduce again. > > I don't apply your patch yet. but mapped ratio is reduced only very little. > > mapped ratio or absolute numbers? The ratio wont change much because > nr_mapped is already small. My box is running Fedora 10 initlevel 5 (GNOME desktop). many GNOME component is mapped very many process (likes >50). Thus, these page aren't dropped by typical any workload. > > I think smem can show which library evicted. Can you try it? > > > > download: http://www.selenic.com/smem/ > > usage: ./smem -m -r --abbreviate > > Sure, but I don't see much change in its output (see attachments). > > smem-console-0 is collected after fresh boot, > smem-console-1 is collected after the big IO. hmmmm, your result has following characatistics. - no graphics component - very few mapped library (it is almost only zsh library) Can you try test on X environment? > > We can't decide 9/10 is important or not. we need know actual evicted file list. > > Right. But what I measured is the activeness. Almost zero major page > faults means the evicted 90% mapped pages are inactive during the > long 300 seconds of IO. Agreed. IOW, I don't think your test environment is typical desktop... -- 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: email@kvack.org