From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 4 Apr 2007 16:55:32 +0300 From: Dan Aloni Subject: Re: [rfc] no ZERO_PAGE? Message-ID: <20070404135530.GA29026@localdomain> References: <20070329075805.GA6852@wotan.suse.de> <20070330024048.GG19407@wotan.suse.de> <20070404033726.GE18507@wotan.suse.de> <20070404102407.GA529@wotan.suse.de> <20070404122701.GB19587@v2.random> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070404122701.GB19587@v2.random> Sender: owner-linux-mm@kvack.org Return-Path: To: Andrea Arcangeli Cc: Nick Piggin , Hugh Dickins , Andrew Morton , Linus Torvalds , Linux Memory Management List , tee@sgi.com, holt@sgi.com, Linux Kernel Mailing List List-ID: On Wed, Apr 04, 2007 at 02:27:01PM +0200, Andrea Arcangeli wrote: > On Wed, Apr 04, 2007 at 12:24:07PM +0200, Nick Piggin wrote: > > But for a potential mainline merge, maybe starting with a CONFIG > > option is a good idea -- defaulting to off, and we could start by > > turning it on just in -rc kernels for a few releases, to get a bit > > more confidence? > > The only reason to do that is if there are many stupid apps pretending > to get meaningful information from pages that cannot contain any > information. The zero page in the anon page fault has been there > forever so... There might be a lot of applications like that, and I'm not sure that _all_ of them can be considered 'stupid' as you say. How about applications that perform mmap() and R/W random-access on large *sparse* files? (e.g. a scientific app that uses a large sparse file as a big database look-up table). As I see it, these apps would need to keep track of what's sparse and what's not... -- Dan Aloni XIV LTD, http://www.xivstorage.com da-x (at) monatomic.org, dan (at) xiv.co.il -- 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