From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 9E9566B004F for ; Mon, 13 Jul 2009 03:03:24 -0400 (EDT) Date: Mon, 13 Jul 2009 09:24:38 +0200 From: Nick Piggin Subject: Re: [RFC][PATCH 0/4] ZERO PAGE again v2 Message-ID: <20090713072438.GP14666@wotan.suse.de> References: <20090707165101.8c14b5ac.kamezawa.hiroyu@jp.fujitsu.com> <20090707084750.GX2714@wotan.suse.de> <20090707180629.cd3ac4b6.kamezawa.hiroyu@jp.fujitsu.com> <20090708173206.GN356@random.random> <20090713064641.GL14666@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090713064641.GL14666@wotan.suse.de> Sender: owner-linux-mm@kvack.org To: Hugh Dickins Cc: Andrea Arcangeli , KAMEZAWA Hiroyuki , "linux-mm@kvack.org" , avi@redhat.com, akpm@linux-foundation.org, torvalds@linux-foundation.org List-ID: On Mon, Jul 13, 2009 at 08:46:41AM +0200, Nick Piggin wrote: > On Fri, Jul 10, 2009 at 12:18:07PM +0100, Hugh Dickins wrote: > > On Wed, 8 Jul 2009, Andrea Arcangeli wrote: > > > On Tue, Jul 07, 2009 at 06:06:29PM +0900, KAMEZAWA Hiroyuki wrote: > > > harmful as there's a double page fault generated instead of a single > > > one, kksmd has a cost but zeropage isn't free either in term of page > > > faults too) > > > > Much as I like KSM, I have to agree with Avi, that if people are > > wanting the ZERO_PAGE back in compute-intensive loads, then relying > > I can't imagine ZERO_PAGE would be too widely used in compute-intensive > loads. At least, not serious stuff. Nobody wants to spend 4K of cache > and one TLB entry for one or two non-zero floating point numbers in a > big sparse matrix. Not to mention the cache and memory overhead of just > scanning through lots of zeros. Heh, oops: before anyone thinks it will be fun to make some personal insults, there won't be much memory overhead from zero page of course! Cache and *TLB* overhead is going to be involved. -- 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