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 SMTP id E1C156007E1 for ; Tue, 5 Jan 2010 10:17:55 -0500 (EST) Date: Tue, 5 Jan 2010 09:17:11 -0600 (CST) From: Christoph Lameter Subject: Re: [RFC][PATCH 6/8] mm: handle_speculative_fault() In-Reply-To: <20100105054536.44bf8002@infradead.org> Message-ID: References: <20100104182429.833180340@chello.nl> <20100104182813.753545361@chello.nl> <20100105054536.44bf8002@infradead.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Arjan van de Ven Cc: Peter Zijlstra , "Paul E. McKenney" , Peter Zijlstra , KAMEZAWA Hiroyuki , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "minchan.kim@gmail.com" , "hugh.dickins" , Nick Piggin , Ingo Molnar , Linus Torvalds List-ID: On Tue, 5 Jan 2010, Arjan van de Ven wrote: > while I appreciate the goal of reducing contention on this lock... > wouldn't step one be to remove the page zeroing from under this lock? > that's by far (easily by 10x I would guess) the most expensive thing > that's done under the lock, and I would expect a first order of > contention reduction just by having the zeroing of a page not done > under the lock... The main issue is cacheline bouncing. mmap sem is a rw semaphore and only held for read during a fault. -- 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