From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 3A1CF6B0044 for ; Wed, 16 Dec 2009 05:11:15 -0500 (EST) Date: Wed, 16 Dec 2009 11:11:07 +0100 From: Andi Kleen Subject: Re: [mm][RFC][PATCH 0/11] mm accessor updates. Message-ID: <20091216101107.GA15031@basil.fritz.box> References: <20091216120011.3eecfe79.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091216120011.3eecfe79.kamezawa.hiroyu@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , cl@linux-foundation.org, "akpm@linux-foundation.org" , "mingo@elte.hu" , andi@firstfloor.org, minchan.kim@gmail.com List-ID: On Wed, Dec 16, 2009 at 12:00:11PM +0900, KAMEZAWA Hiroyuki wrote: > This is from Christoph Lameter's mm_accessor patch posted 5/Nov. > > Replacing all access to mm->mmap_sem with mm-accessor functions as > mm_read_lock, > mm_write_lock, > etc... > > This kind of function allows us to improve page fault performance etc.. > For example, skil down_read(mmap_sem) in some situation. > (as: http://marc.info/?l=linux-mm&m=125809791306459&w=2) The problem is that it also slows down the writers, and we have some workloads where writing is the bottleneck. I don't think this is the right trade off at this time. Also the patches didn't fare too well in testing unfortunately. I suspect we'll rather need multiple locks split per address space range. -Andi -- ak@linux.intel.com -- Speaking for myself only. -- 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