From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 527776B004F for ; Tue, 15 Sep 2009 16:15:52 -0400 (EDT) Date: Tue, 15 Sep 2009 21:15:07 +0100 (BST) From: Hugh Dickins Subject: Re: [PATCH 7/8] mm: reinstate ZERO_PAGE In-Reply-To: <20090909104423.4bd23a2c.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <20090908113734.869cdad7.kamezawa.hiroyu@jp.fujitsu.com> <20090909104423.4bd23a2c.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Hugh Dickins , Andrew Morton , KOSAKI Motohiro , Linus Torvalds , Nick Piggin , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Wed, 9 Sep 2009, KAMEZAWA Hiroyuki wrote: > On Tue, 8 Sep 2009 12:56:57 +0100 (BST) > Hugh Dickins wrote: > > > > Though I like that we don't _need_ to change mlock.c for reinstated > > ZERO_PAGE, this morning I'm having trouble persuading myself that > > mlocking a readonly anonymous area is too silly to optimize for. > > > > Maybe the very people who persuaded you to bring back the anonymous > > use of ZERO_PAGE, are also doing a huge mlock of the area first? > No, as far as I know, they'll not do huge mlock. Thanks for that (not entirely conclusive!) info. I've decided for the moment to make a couple of further optimizations in mlock.c (along with the comment you asked for), and leave adding another __get_user_pages flag until a case for it is demonstrated. Small patch series following shortly. Hugh -- 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