From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 8 Apr 2003 18:19:11 -0700 From: William Lee Irwin III Subject: Re: meminfo documentation Message-ID: <20030409011911.GA21761@holomorphy.com> References: <3E936E2A.4080400@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3E936E2A.4080400@us.ibm.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Dave Hansen Cc: linux-mm@kvack.org List-ID: On Tue, Apr 08, 2003 at 05:49:46PM -0700, Dave Hansen wrote: > ReverseMaps: number of rmap pte chains It's not about the number of pte_chains. There are 3 ways to think of it: (1) number of reverse mappings performed. (2) total number of pte's in pte_chains (3) total faulted-in memory-backed virtualspace pte_chain objects may partially utilize slabs, and a given chain of pte_chain objects may be partially utilized within a given chain, as there are 7 pointers or so in an object, and you have to fill a chain with a precise number of pte's to fully utilize the objects. So, there are two levels at which internal fragmentation can happen. This measures the one _not_ detectable from /proc/slabinfo, which is the internal fragmentation at the pte-filling-object-level. The number these days is not particularly useful for the measurement of internal fragmentation due to the PG_direct changes, but could be fixed up to measure it again. This stat is slated to be removed soon because it's measurably expensive to collect (which is good; any stat with that kind of performance impact should either die or be config'd). -- wli -- 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: aart@kvack.org