From mboxrd@z Thu Jan 1 00:00:00 1970 From: cyril@ti.com (Cyril Chemparathy) Date: Fri, 1 Feb 2013 11:13:48 -0500 Subject: [PATCH v4 00/13] ARM LPAE Fixes - Part 1 In-Reply-To: <20130201151410.GR23505@n2100.arm.linux.org.uk> References: <1359669512-31276-1-git-send-email-cyril@ti.com> <510BDAED.8060805@ti.com> <20130201151410.GR23505@n2100.arm.linux.org.uk> Message-ID: <510BE9BC.9090701@ti.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 02/01/2013 10:14 AM, Russell King - ARM Linux wrote: > On Fri, Feb 01, 2013 at 10:10:37AM -0500, Cyril Chemparathy wrote: >> With this, I ran simple network and filesystem performance tests to >> compare the code-patching vs. non-code-patching variants. These tests >> didn't yield any significant performance difference between the two on >> an ARMv7 (Cortex-A8) platform. > > It's not network and fs activity that this kind of stuff is likely to > show up in, but more to do with walking pages tables and the like - > remember that page tables are stored using physical addresses, and any > walks of them have to convert those physical addresses to virtual > addresses and back again. > > So, things like page scanning for eviction (eg, page aging, page > faults even those which just re-use a page from the page cache) have > to use the v:p / p:v translation macros. > Thanks, Russell. Any recommendations on how to best benchmark this? Thanks -- Cyril. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756673Ab3BAQOM (ORCPT ); Fri, 1 Feb 2013 11:14:12 -0500 Received: from devils.ext.ti.com ([198.47.26.153]:37310 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756128Ab3BAQOK (ORCPT ); Fri, 1 Feb 2013 11:14:10 -0500 Message-ID: <510BE9BC.9090701@ti.com> Date: Fri, 1 Feb 2013 11:13:48 -0500 From: Cyril Chemparathy User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 MIME-Version: 1.0 To: Russell King - ARM Linux CC: Nicolas Pitre , , , , Will Deacon , , Catalin Marinas , , Subject: Re: [PATCH v4 00/13] ARM LPAE Fixes - Part 1 References: <1359669512-31276-1-git-send-email-cyril@ti.com> <510BDAED.8060805@ti.com> <20130201151410.GR23505@n2100.arm.linux.org.uk> In-Reply-To: <20130201151410.GR23505@n2100.arm.linux.org.uk> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/01/2013 10:14 AM, Russell King - ARM Linux wrote: > On Fri, Feb 01, 2013 at 10:10:37AM -0500, Cyril Chemparathy wrote: >> With this, I ran simple network and filesystem performance tests to >> compare the code-patching vs. non-code-patching variants. These tests >> didn't yield any significant performance difference between the two on >> an ARMv7 (Cortex-A8) platform. > > It's not network and fs activity that this kind of stuff is likely to > show up in, but more to do with walking pages tables and the like - > remember that page tables are stored using physical addresses, and any > walks of them have to convert those physical addresses to virtual > addresses and back again. > > So, things like page scanning for eviction (eg, page aging, page > faults even those which just re-use a page from the page cache) have > to use the v:p / p:v translation macros. > Thanks, Russell. Any recommendations on how to best benchmark this? Thanks -- Cyril.