From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [rfc] no ZERO_PAGE? In-Reply-To: Your message of "Wed, 04 Apr 2007 08:35:30 PDT." From: Valdis.Kletnieks@vt.edu References: <20070329075805.GA6852@wotan.suse.de> <20070330024048.GG19407@wotan.suse.de> <20070404033726.GE18507@wotan.suse.de> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1175724355_4061P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Wed, 04 Apr 2007 18:05:55 -0400 Message-ID: <6701.1175724355@turing-police.cc.vt.edu> Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: Nick Piggin , Hugh Dickins , Andrew Morton , Linux Memory Management List , tee@sgi.com, holt@sgi.com, Andrea Arcangeli , Linux Kernel Mailing List List-ID: --==_Exmh_1175724355_4061P Content-Type: text/plain; charset=us-ascii On Wed, 04 Apr 2007 08:35:30 PDT, Linus Torvalds said: > Although I don't know how much -mm will do for it. There is certainly not > going to be any correctness problems, afaik, just *performance* problems. > Does anybody do any performance testing on -mm? I have to admit I don't do anything more definite than "wow, this goes oink"... > That's an example of an app that actually cares about the page allocation > (or, in this case, the lack there-of). Not an important one, but maybe > there are important ones that care? I'd not be surprised if there's sparse-matrix code out there that wants to malloc a *huge* array (like a 1025x1025 array of numbers) that then only actually *writes* to several hundred locations, and relies on the fact that all the untouched pages read back all-zeros. Of course, said code is probably buggy because it doesn't zero the whole thing because you don't usually know if some other function already scribbled on that heap page. This would probably be more interesting if we had a userspace API for "Give me a metric buttload of zero page frames" that malloc() and friends could leverage..... --==_Exmh_1175724355_4061P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFGFCFDcC3lWbTT17ARAkaMAKC1t7k+Vp8jNmXti0Lo1j4JVvGhiACgi4Ve Px3K6ou1dKC8hS9yVlYeqww= =RAk6 -----END PGP SIGNATURE----- --==_Exmh_1175724355_4061P-- -- 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