From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e3.ny.us.ibm.com (8.13.8/8.13.8) with ESMTP id m8OJNQZ4008082 for ; Wed, 24 Sep 2008 15:23:26 -0400 Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id m8OJNE5s018898 for ; Wed, 24 Sep 2008 13:23:14 -0600 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m8OJNDDp008048 for ; Wed, 24 Sep 2008 13:23:13 -0600 Subject: Re: [PATCH 1/2] Report the pagesize backing a VMA in /proc/pid/smaps From: Dave Hansen In-Reply-To: <20080924191107.GA31324@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> Content-Type: text/plain Date: Wed, 24 Sep 2008 12:23:10 -0700 Message-Id: <1222284190.15523.64.camel@nimitz> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Mel Gorman Cc: KOSAKI Motohiro , agl@us.ibm.com, LKML , Linux-MM List-ID: 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. -- Dave -- 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