From patchwork Tue Nov 5 17:26:49 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Majewski X-Patchwork-Id: 3143011 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 2C2989F3C4 for ; Tue, 5 Nov 2013 17:28:51 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id C99FE2031C for ; Tue, 5 Nov 2013 17:28:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E6A18205CA for ; Tue, 5 Nov 2013 17:28:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755403Ab3KER1n (ORCPT ); Tue, 5 Nov 2013 12:27:43 -0500 Received: from mailout1.samsung.com ([203.254.224.24]:60028 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755372Ab3KER1k (ORCPT ); Tue, 5 Nov 2013 12:27:40 -0500 Received: from epcpsbgm1.samsung.com (epcpsbgm1 [203.254.230.26]) by mailout1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MVS00CH2WHN5H30@mailout1.samsung.com>; Wed, 06 Nov 2013 02:27:39 +0900 (KST) X-AuditID: cbfee61a-b7f836d0000025d7-8d-52792a8bf545 Received: from epmmp2 ( [203.254.227.17]) by epcpsbgm1.samsung.com (EPCPMTA) with SMTP id 98.E5.09687.B8A29725; Wed, 06 Nov 2013 02:27:39 +0900 (KST) Received: from mcdsrvbld02.digital.local ([106.116.37.23]) by mmp2.samsung.com (Oracle Communications Messaging Server 7u4-24.01 (7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTPA id <0MVS00GMQWGVG8A0@mmp2.samsung.com>; Wed, 06 Nov 2013 02:27:38 +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 , Myungjoo Ham , durgadoss.r@intel.com, Amit Daniel Kachhap Subject: [PATCH v10 5/7] Documentation:cpufreq:boost: Update BOOST documentation Date: Tue, 05 Nov 2013 18:26:49 +0100 Message-id: <1383672411-26324-6-git-send-email-l.majewski@samsung.com> X-Mailer: git-send-email 1.7.10 In-reply-to: <1383672411-26324-1-git-send-email-l.majewski@samsung.com> References: <1370502472-7249-1-git-send-email-l.majewski@samsung.com> <1383672411-26324-1-git-send-email-l.majewski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrHLMWRmVeSWpSXmKPExsVy+t9jQd1urcogg2PX2S0aroZYbJyxntXi adMPdou+n1eYLdbs/8lk0Xn2CbPFm0fcFm8ebma0uLxrDpvF594jjBa3G1ewWZw5fYnV4snD PjaLjV89HPg8Fu95yeRx59oeNo91094ye2y52s7i0bdlFaPH8RvbmTw+b5ILYI/isklJzcks Sy3St0vgyrhxeApLwQ7Jii/zpBsYX4p0MXJySAiYSJzpW8QMYYtJXLi3ng3EFhKYzigxsVm+ i5ELyO5ikvh0cBkTSIJNQE/i892nTCAJEYEljBKvmxawgjjMAnuZJSb9WQvkcHAICwRIXPnq DNLAIqAq8WXRe0YQm1fATeLyh63sENvkJZ7e7wPbxingLrFj1l42iG1NjBJvbk9gmsDIu4CR YRWjaGpBckFxUnquoV5xYm5xaV66XnJ+7iZGcKg+k9rBuLLB4hCjAAejEg9vgnxlkBBrYllx Ze4hRgkOZiUR3mP/K4KEeFMSK6tSi/Lji0pzUosPMUpzsCiJ8x5otQ4UEkhPLEnNTk0tSC2C yTJxcEo1MEbWz3jME6LYEpQzOcvylTzzGYZJ0ypYTNMn/F9+4eDMr/9v6nknSDstYJrRtPbP G++TjM1r3/Mbtwoc8HyypuMsV+3ET853ds5TeSnl+u1npFyMXeibW3dqw3/dtmFmS+dI/eyg 3WN84IpF19/ZS64n30jiZVZ1/RWZdXe6rs6ujmyDuZVFIUosxRmJhlrMRcWJAHzFeM5RAgAA Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Spam-Status: No, score=-6.9 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 v10: - None Changes for v9: - None Changes for v8: - None 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