From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 5A6CC5F0001 for ; Tue, 14 Apr 2009 03:16:57 -0400 (EDT) Received: from m1.gw.fujitsu.co.jp ([10.0.50.71]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n3E7HAsx021742 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Tue, 14 Apr 2009 16:17:11 +0900 Received: from smail (m1 [127.0.0.1]) by outgoing.m1.gw.fujitsu.co.jp (Postfix) with ESMTP id B0E2245DD76 for ; Tue, 14 Apr 2009 16:17:10 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (s1.gw.fujitsu.co.jp [10.0.50.91]) by m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 8DE3A45DD74 for ; Tue, 14 Apr 2009 16:17:10 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id 76623E08008 for ; Tue, 14 Apr 2009 16:17:10 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.249.87.103]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id D0ECEE08002 for ; Tue, 14 Apr 2009 16:17:09 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [RFC][PATCH] proc: export more page flags in /proc/kpageflags In-Reply-To: <20090414071159.GV14687@one.firstfloor.org> References: <20090414154606.C665.A69D9226@jp.fujitsu.com> <20090414071159.GV14687@one.firstfloor.org> Message-Id: <20090414161211.C66E.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Tue, 14 Apr 2009 16:17:09 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Andi Kleen Cc: kosaki.motohiro@jp.fujitsu.com, Wu Fengguang , Andrew Morton , LKML , "linux-mm@kvack.org" List-ID: > On Tue, Apr 14, 2009 at 03:54:40PM +0900, KOSAKI Motohiro wrote: > > Hi > > There are two use cases here: > > First what is useful for the administrator as a general abstraction. > And what is useful for the kernel hacker for debugging. > > The kernel hacker wants everything even if it's subject to change, > the administrator wants a higher level abstraction they can make > sense of and that doesn't change too often. > > I think there's a case for both usages, but perhaps they > should be separated (in a public and a internal interface perhaps?) > > My comments below are about abstractions for the first case. > > > > > > > On Tue, Apr 14, 2009 at 12:37:10PM +0800, KOSAKI Motohiro wrote: > > > > > Export the following page flags in /proc/kpageflags, > > > > > just in case they will be useful to someone: > > > > > > > > > > - PG_swapcache > > > > > - PG_swapbacked > > > > > - PG_mappedtodisk > > > > > - PG_reserved > > PG_reserved should be exported as PG_KERNEL or somesuch. OK. rest problem is, how do we write document this. PG_reserved have multiple meanings... > > > > > - PG_private > > > > > - PG_private_2 > > > > > - PG_owner_priv_1 > > > > > > > > > > - PG_head > > > > > - PG_tail > > > > > - PG_compound > > I would combine these three into a pseudo "large page" flag. Ah good idea. > > > > > > > > > > - PG_unevictable > > > > > - PG_mlocked > > > > > > > > > > - PG_poison > > PG_poison is also useful to export. But since it depends on my > patchkit I will pull a patch for that into the HWPOISON series. Yes, I agree. > > > > > - PG_unevictable > > > > > - PG_mlocked > > > > this 9 flags shouldn't exported. > > I can't imazine administrator use what purpose those flags. > > I think an abstraced "PG_pinned" or somesuch flag that combines > page lock, unevictable, mlocked would be useful for the administrator. PG_unevictable and PG_mlocked have a bit delicate meaning. it gurantee the page isn't evicted. but mlock(2) don't gurantee turn page on PG_mlocked. some race prevent it. I'm afraid administrator confuse it. but if someone can write good document, my worriness will vanished. -- 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