From: "KOSAKI Motohiro" Subject: Re: [RFC] Parallelize IO for e2fsck Date: Sun, 3 Feb 2008 22:51:10 +0900 Message-ID: <2f11576a0802030551s53eeb7b3k450254f3d2cf9ab7@mail.gmail.com> References: <70b6f0bf0801161322k2740a8dch6a0d6e6e112cd2d0@mail.gmail.com> <70b6f0bf0801161330y46ec555m5d4994a1eea7d045@mail.gmail.com> <20080121230041.GL3180@webber.adilger.int> <20080122033830.GR155259@sgi.com> <3673.1200975438@turing-police.cc.vt.edu> <20080122070050.GM3180@webber.adilger.int> <20080122144052.GC17804@mit.edu> <20080128193005.GC4032@ucw.cz> <20080128195633.GB20528@mit.edu> <20080128200105.GA4719@ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "Theodore Tso" , Valdis.Kletnieks@vt.edu, "David Chinner" , "Valerie Henson" , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, "Andreas Dilger" , "Ric Wheeler" , kosaki.motohiro@jp.fujitsu.com To: "Pavel Machek" Return-path: Received: from py-out-1112.google.com ([64.233.166.176]:63973 "EHLO py-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752766AbYBCNvO (ORCPT ); Sun, 3 Feb 2008 08:51:14 -0500 Received: by py-out-1112.google.com with SMTP id u52so2678457pyb.10 for ; Sun, 03 Feb 2008 05:51:11 -0800 (PST) In-Reply-To: <20080128200105.GA4719@ucw.cz> Content-Disposition: inline Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi Pavel > > > As user pages are always in highmem, this should be easy to decide: > > > only send SIGDANGER when highmem is full. (Yes, there are > > > inodes/dentries/file descriptors in lowmem, but I doubt apps will > > > respond to SIGDANGER by closing files). > > > > Good point; for a system with at least (say) 2GB of memory, that > > definitely makes sense. For a system with less than 768 megs of > > memory (how quaint, but it wasn't that long ago this was a lot of > > memory :-), there wouldn't *be* any memory in highmem at all.... > > Ok, so it is 'send SIGDANGER when all zones are low', because user > allocations can go from all zones (unless you have something really > exotic, I'm not sure if that is true on huge NUMA machines & similar). thank you good point out. to be honest, the zone awareness of current mem_notify is premature. I think we need enhancement rss statistics to per zone rss. but not implemented yet ;-) and, unfortunately I have no highmem machine. the mem_notify is not so tested on highmem machine. if you help to test, I am very happy! Thanks.