From patchwork Tue Aug 13 10:08:24 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Majewski X-Patchwork-Id: 2843542 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 3238DBF546 for ; Tue, 13 Aug 2013 10:09:55 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 23E1B204CE for ; Tue, 13 Aug 2013 10:09:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B4BA8204BC for ; Tue, 13 Aug 2013 10:09:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754225Ab3HMKJQ (ORCPT ); Tue, 13 Aug 2013 06:09:16 -0400 Received: from mailout1.samsung.com ([203.254.224.24]:63259 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754613Ab3HMKJN (ORCPT ); Tue, 13 Aug 2013 06:09:13 -0400 Received: from epcpsbgm2.samsung.com (epcpsbgm2 [203.254.230.27]) by mailout1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MRG00JSGS7CENQ0@mailout1.samsung.com>; Tue, 13 Aug 2013 19:09:12 +0900 (KST) X-AuditID: cbfee61b-b7efe6d000007b11-45-520a05c8f4e1 Received: from epmmp1.local.host ( [203.254.227.16]) by epcpsbgm2.samsung.com (EPCPMTA) with SMTP id 53.4A.31505.8C50A025; Tue, 13 Aug 2013 19:09:12 +0900 (KST) Received: from mcdsrvbld02.digital.local ([106.116.37.23]) by mmp1.samsung.com (Oracle Communications Messaging Server 7u4-24.01 (7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTPA id <0MRG004H7S63ZN80@mmp1.samsung.com>; Tue, 13 Aug 2013 19:09:12 +0900 (KST) From: Lukasz Majewski To: Viresh Kumar , "Rafael J. Wysocki" , Zhang Rui , Eduardo Valentin Cc: "cpufreq@vger.kernel.org" , Linux PM list , Jonghwa Lee , Lukasz Majewski , Lukasz Majewski , linux-kernel , Bartlomiej Zolnierkiewicz , Daniel Lezcano , Kukjin Kim , Myungjoo Ham , durgadoss.r@intel.com Subject: [PATCH v7 6/7] Documentation:cpufreq:boost: Update BOOST documentation Date: Tue, 13 Aug 2013 12:08:24 +0200 Message-id: <1376388505-30233-7-git-send-email-l.majewski@samsung.com> X-Mailer: git-send-email 1.7.10 In-reply-to: <1376388505-30233-1-git-send-email-l.majewski@samsung.com> References: <1370502472-7249-1-git-send-email-l.majewski@samsung.com> <1376388505-30233-1-git-send-email-l.majewski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrKLMWRmVeSWpSXmKPExsVy+t9jAd0TrFxBBp8/KFhsnLGe1eJp0w92 i3mfZS36fl5htliz/yeTRefZJ8wWvQuuslm8ecRt8ebhZkaLy7vmsFl87j3CaHG7cQWbRf/C XiaLJw/72Cw2fvVw4PdYvOclk8eda3vYPNZNe8vs0bdlFaPHo8UtjB7Hb2xn8vi8SS6APYrL JiU1J7MstUjfLoEr4/HCl8wFWyQqdu+aw9zA2CrSxcjJISFgIrF9xTsmCFtM4sK99WxdjFwc QgKLGCUmPZsO5XQxSay4OJENpIpNQE/i892nYB0iAnMYJe4cdQcpYhZ4wCyx+PsXRpCEsIC/ RHvzUzCbRUBVYtK7BWA2r4CbxKsLJ1gh1slLPL3fBzaUU8BdYvX/FqhtTYwSHccOs01g5F3A yLCKUTS1ILmgOCk910ivODG3uDQvXS85P3cTIzhwn0nvYFzVYHGIUYCDUYmHN+MjR5AQa2JZ cWXuIUYJDmYlEd44Rq4gId6UxMqq1KL8+KLSnNTiQ4zSHCxK4rwHW60DhQTSE0tSs1NTC1KL YLJMHJxSDYycMld3p+UVqV2+dSnce2PaZe3G5WVr+CWeXE9T/aXs+/Cf5cJN7xlSP4lJ16/6 /XVF3nsO5p6P2hxtcc8LVRrKA52naf/iqSq8eTdzwqJ4A9v/zzYZNF/5539T7g5HrbwH0+ZF /jqCS/1zCzq0/9vHbfyQzZ63/HHvywuv71SuEeif3Ft6p0WJpTgj0VCLuag4EQANX837WAIA AA== Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Spam-Status: No, score=-9.7 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Since the support for software and hardware controlled boosting has been added, the corresponding Documentation entry had been updated. Signed-off-by: Lukasz Majewski Signed-off-by: Myungjoo Ham Acked-by: Viresh Kumar --- Changes for v7: - None Changes for v6: - None Changes for v5: - New patch Documentation/cpu-freq/boost.txt | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) diff --git a/Documentation/cpu-freq/boost.txt b/Documentation/cpu-freq/boost.txt index 9b4edfc..dd62e13 100644 --- a/Documentation/cpu-freq/boost.txt +++ b/Documentation/cpu-freq/boost.txt @@ -17,8 +17,8 @@ Introduction Some CPUs support a functionality to raise the operating frequency of some cores in a multi-core package if certain conditions apply, mostly if the whole chip is not fully utilized and below it's intended thermal -budget. This is done without operating system control by a combination -of hardware and firmware. +budget. The decision about boost disable/enable is made either at hardware +(e.g. x86) or software (e.g ARM). On Intel CPUs this is called "Turbo Boost", AMD calls it "Turbo-Core", in technical documentation "Core performance boost". In Linux we use the term "boost" for convenience. @@ -48,24 +48,24 @@ be desirable: User controlled switch ---------------------- -To allow the user to toggle the boosting functionality, the acpi-cpufreq -driver exports a sysfs knob to disable it. There is a file: +To allow the user to toggle the boosting functionality, the cpufreq core +driver exports a sysfs knob to enable or disable it. There is a file: /sys/devices/system/cpu/cpufreq/boost which can either read "0" (boosting disabled) or "1" (boosting enabled). -Reading the file is always supported, even if the processor does not -support boosting. In this case the file will be read-only and always -reads as "0". Explicitly changing the permissions and writing to that -file anyway will return EINVAL. +The file is exported only when cpufreq driver supports boosting. +Explicitly changing the permissions and writing to that file anyway will +return EINVAL. On supported CPUs one can write either a "0" or a "1" into this file. This will either disable the boost functionality on all cores in the -whole system (0) or will allow the hardware to boost at will (1). +whole system (0) or will allow the software or hardware to boost at will +(1). Writing a "1" does not explicitly boost the system, but just allows the -CPU (and the firmware) to boost at their discretion. Some implementations -take external factors like the chip's temperature into account, so -boosting once does not necessarily mean that it will occur every time -even using the exact same software setup. +CPU to boost at their discretion. Some implementations take external +factors like the chip's temperature into account, so boosting once does +not necessarily mean that it will occur every time even using the exact +same software setup. AMD legacy cpb switch