From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753079Ab1BDV2d (ORCPT ); Fri, 4 Feb 2011 16:28:33 -0500 Received: from e38.co.us.ibm.com ([32.97.110.159]:43191 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752771Ab1BDV2c (ORCPT ); Fri, 4 Feb 2011 16:28:32 -0500 Subject: Re: [RFC][PATCH 1/6] count transparent hugepage splits From: Dave Hansen To: Andrea Arcangeli Cc: David Rientjes , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michael J Wolf In-Reply-To: <20110204211825.GJ30909@random.random> References: <20110201003357.D6F0BE0D@kernel> <20110201003358.98826457@kernel> <20110204211825.GJ30909@random.random> Content-Type: text/plain; charset="ANSI_X3.4-1968" Date: Fri, 04 Feb 2011 13:28:25 -0800 Message-ID: <1296854905.6737.2631.camel@nimitz> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2011-02-04 at 22:18 +0100, Andrea Arcangeli wrote: > On Thu, Feb 03, 2011 at 01:22:14PM -0800, David Rientjes wrote: > > i.e. no global locking, but we've accepted the occassional off-by-one > > error (even though splitting of hugepages isn't by any means lightning > > fast and the overhead of atomic ops would be negligible). > > Agreed losing an increment is not a problem, but in very large systems > it will become a bottleneck. It's not super urgent, but I think it > needs to become a per-cpu counter sooner than later (not needed > immediately but I would appreciate an incremental patch soon to > address that). Seems like something that would be fairly trivial with the existing count_vm_event() infrastructure. Any reason not to use that? I'll be happy to tack a patch on to my series. -- Dave