From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750868Ab3AHFD6 (ORCPT ); Tue, 8 Jan 2013 00:03:58 -0500 Received: from terminus.zytor.com ([198.137.202.10]:57320 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750718Ab3AHFD5 (ORCPT ); Tue, 8 Jan 2013 00:03:57 -0500 Message-ID: <50EBA8AB.2060003@zytor.com> Date: Mon, 07 Jan 2013 21:03:39 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Shaohua Li CC: Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mingo@redhat.com, hughd@google.com Subject: Re: [RFC]x86: clearing access bit don't flush tlb References: <20130107081213.GA21779@kernel.org> <50EAE66B.1020804@redhat.com> <50EB4CB9.9010104@zytor.com> <20130108045519.GB2459@kernel.org> In-Reply-To: <20130108045519.GB2459@kernel.org> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/07/2013 08:55 PM, Shaohua Li wrote: > > I searched a little bit, the change (doing TLB flush to clear access bit) is > made between 2.6.7 - 2.6.8, I can't find the changelog, but I found a patch: > http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.7-rc2/2.6.7-rc2-mm2/broken-out/mm-flush-tlb-when-clearing-young.patch > > The changelog declaims this is for arm/ppc/ppc64. > Not really. It says that those have stumbled over it already. It is true in general that this change will make very frequently used pages (which stick in the TLB) candidates for eviction. x86 would seem to be just as affected, although possibly with a different frequency. Do we have any actual metrics on anything here? -hpa