From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 24 Sep 2008 18:10:04 +0100 From: Mel Gorman Subject: Re: [PATCH 1/2] Report the pagesize backing a VMA in /proc/pid/smaps Message-ID: <20080924171003.GD10837@csn.ul.ie> References: <20080923211140.DC16.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20080923194655.GA25542@csn.ul.ie> <20080924210309.8C3B.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20080924154120.GA10837@csn.ul.ie> <1222272395.15523.3.camel@nimitz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1222272395.15523.3.camel@nimitz> Sender: owner-linux-mm@kvack.org Return-Path: To: Dave Hansen Cc: KOSAKI Motohiro , agl@us.ibm.com, LKML , Linux-MM List-ID: On (24/09/08 09:06), Dave Hansen didst pronounce: > On Wed, 2008-09-24 at 16:41 +0100, Mel Gorman wrote: > > I admit it's ppc64-specific. In the latest patch series, I made this a > > separate patch so that it could be readily dropped again for this reason. > > Maybe an alternative would be to display MMUPageSize *only* where it differs > > from KernelPageSize. Would that be better or similarly confusing? > > I would also think that any arch implementing fallback from large to > small pages in a hugetlbfs area (Adam needs to post his patches :) would > also use this. > Fair point. Maybe the thing to do is backburner this patch for the moment and reintroduce it when/if an architecture supports demotion? The KernelPageSize reporting in smaps and what the hpagesize in maps is still useful though I believe. Any comment? (future stuff from here on) In the future if demotion does happen then the MMUPageSize information may be genuinely useful instead of just a curious oddity on ppc64. As you point out, Adam (added to cc) has worked on this area (starting with x86 demotion) in the past but it's a while before it'll be considered for merging I believe. That aside, more would need to be done with the page size reporting then anyway. For example, it maybe indicate how much of each pagesize is in a VMA or indicate that KernelPageSize is what is being requested but in reality it is mixed like; KernelPageSize: 2048 kB (mixed) or KernelPageSize: 2048 kB * 5, 4096 kB * 20 -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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