From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 18 Aug 2003 14:19:16 +0100 (IST) From: Mel Gorman Subject: Re: [RFC] prefault optimization In-Reply-To: <3F32ECE0.1000102@us.ibm.com> Message-ID: References: <3F32ECE0.1000102@us.ibm.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Adam Litke Cc: linux-mm@kvack.org, "Martin J. Bligh" List-ID: On Thu, 7 Aug 2003, Adam Litke wrote: > This patch attempts to reduce page fault overhead for mmap'd files. All > pages in the page cache that will be managed by the current vma are > instantiated in the page table. I believe this could punish applications which use large numbers of shared libraries, especially if only a small portion of library code is used. Take something like konqueror which maps over 30 shared libraries. With prefaulting, all the libraries will be fully faulted even if only a tiny portion of some library code is used. This, potentially, could put a lot of unwanted pages into the page cache which will be a kick in the pants for low-memory systems. For example, I don't have audio enabled at all in konqueror, but with this patch, it will fault in 77K of data for libaudio that won't be used. Just my 2c -- Mel Gorman http://www.csn.ul.ie/~mel -- 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