From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3BCE20DF.6090103@zytor.com> Date: Wed, 17 Oct 2001 17:22:55 -0700 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Under what conditions are VMAs merged? Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Linux MM mailing list , torvalds@transmeta.com List-ID: Okay, as part of doing this persistent memory system, I apparently need to know better when and if VMAs are merged. The persistent memory obviously does lots of mprotect() to what is otherwise a large private mapping of a file (not anonymous.) In the checkpoint routine I thought doing an mprotect(PROT_READ) on the entire region as a single system call would coalesce the VMAs, but apparently that is not the case; after running my standard stress-test application, /proc/pid/maps show 51635 mappings, most of them contiguous and otherwise matching the surrounding mappings in every way; a dump of /proc/pid/maps is at ftp://terminus.zytor.com/pub/hpa/map.gz for the morbidly curious. This system is running a stock 2.4.12-ac1; the database file is 1 GB+overhead in size (1,074,008,064 bytes to be exact), it is mapped at 0x5f000000. Appreciative for any suggestions. -hpa -- 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/