From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 9 Oct 2007 07:52:39 -0700 (PDT) From: Linus Torvalds Subject: Re: remove zero_page (was Re: -mm merge plans for 2.6.24) In-Reply-To: <200710090117.47610.nickpiggin@yahoo.com.au> Message-ID: References: <20071001142222.fcaa8d57.akpm@linux-foundation.org> <200710030345.10026.nickpiggin@yahoo.com.au> <200710090117.47610.nickpiggin@yahoo.com.au> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=us-ascii Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Hugh Dickins , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Tue, 9 Oct 2007, Nick Piggin wrote: > > I have done some tests which indicate a couple of very basic common tools > don't do much zero-page activity (ie. kbuild). And also combined with some > logical arguments to say that a "sane" app wouldn't be using zero_page much. > (basically -- if the app cares about memory or cache footprint and is using > many pages of zeroes, then it should have a more compressed representation > of zeroes anyway). One of the things that zero-page has been used for is absolutely *huge* (but sparse) arrays in Fortan programs. At least in traditional fortran, it was very hard to do dynamic allocations, so people would allocate the *maximum* array statically, and then not necessarily use everything. I don't know if the pages ever even got paged in, but this is the kind of usage which is *not* insane. Linus -- 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