From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755579AbaGHAns (ORCPT ); Mon, 7 Jul 2014 20:43:48 -0400 Received: from mail-pd0-f171.google.com ([209.85.192.171]:50395 "EHLO mail-pd0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753814AbaGHAnp (ORCPT ); Mon, 7 Jul 2014 20:43:45 -0400 Message-ID: <53BB3EBC.8050005@linaro.org> Date: Tue, 08 Jul 2014 08:43:40 +0800 From: Alex Shi User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Dave Hansen , Mel Gorman CC: x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, ak@linux.intel.com, riel@redhat.com, dave.hansen@linux.intel.com, "H. Peter Anvin" Subject: Re: [PATCH 5/6] x86: mm: new tunable for single vs full TLB flush References: <20140421182418.81CF7519@viggo.jf.intel.com> <20140421182426.D6DD1E8F@viggo.jf.intel.com> <20140424103727.GT23991@suse.de> <53BADC49.6000600@sr71.net> In-Reply-To: <53BADC49.6000600@sr71.net> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/08/2014 01:43 AM, Dave Hansen wrote: > On 04/24/2014 03:37 AM, Mel Gorman wrote: >>> +Despite the fact that a single individual flush on x86 is >>>> +guaranteed to flush a full 2MB, hugetlbfs always uses the full >>>> +flushes. THP is treated exactly the same as normal memory. >>>> + >> You are the second person that told me this and I felt the manual was >> unclear on this subject. I was told that it might be a documentation bug >> but because this discussion was in a bar I completely failed to follow up >> on it. > > For the record... There's a new version of the Intel SDM out, and it > contains some clarifications. They're the easiest to find in this > document which highlights the deltas from the last version: > >> http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developers-manual.pdf > > The documentation for invlpg itself has a new footnote, and there's also > a little bit of new text in section "4.10.2.3 Details of TLB Use". > > The footnotes say: > > If the paging structures map the linear address using a page > larger than 4 KBytes and there are multiple TLB entries for > that page (see Section 4.10.2.3), the instruction (invlpg) > invalidates all of them > > I hope that clears up some of the ambiguity over invlpg. > Uh, AFAICT, the invlpg on large page has no clear effect on data retrieving, on all Intel CPU till ivybridge. No testing on later CPUs. -- Thanks Alex