From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 25 Sep 2008 00:42:13 +0100 From: Mel Gorman Subject: Re: [PATCH 1/2] Report the pagesize backing a VMA in /proc/pid/smaps Message-ID: <20080924234213.GC8598@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> <20080924171003.GD10837@csn.ul.ie> <1222282749.15523.59.camel@nimitz> <20080924191107.GA31324@csn.ul.ie> <1222284190.15523.64.camel@nimitz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1222284190.15523.64.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 12:23), Dave Hansen didst pronounce: > On Wed, 2008-09-24 at 20:11 +0100, Mel Gorman wrote: > > I don't get what you mean by it being sprinkled in each smaps file. How > > would you present the data? > > 1. figure out what the file path is from smaps > 2. look up the mount > 3. look up the page sizes from the mount's information > > > > We should be able to figure out which > > > mount the file is from and, from there, maybe we need some per-mount > > > information exported. > > > > Per-mount information is already exported and you can infer the data about > > huge pagesizes. For example, if you know the default huge pagesize (from > > /proc/meminfo), and the file is on hugetlbfs (read maps, then /proc/mounts) > > and there is no pagesize= mount option (mounts again), you could guess what the > > hugepage that is backing a VMA is. Shared memory segments are a little harder > > but again, you can infer the information if you look around for long enough. > > > > However, this is awkward and not very user-friendly. With the patches (minus > > MMUPageSize as I think we've agreed to postpone that), it's easy to see what > > pagesize is being used at a glance. Without it, you need to know a fair bit > > about hugepages are implemented in Linux to infer the information correctly. > > I agree completely. But, if we consider this a user ABI thing, then > we're stuck with it for a long time, and we better make it flexible > enough to at least contain the gunk we're planning on adding in a small > number of years, like the fallback. We don't want to be adding this > stuff if it isn't going to be stable. > This could also be done as KernelPageSize == Kernel page size that is ideally used in this VMA and later MixedPageSize == Breakdown of the pagesizes that are used in the VMA -- 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