From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753306Ab3LMQkt (ORCPT ); Fri, 13 Dec 2013 11:40:49 -0500 Received: from mailout2.samsung.com ([203.254.224.25]:39206 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753101Ab3LMQjQ (ORCPT ); Fri, 13 Dec 2013 11:39:16 -0500 X-AuditID: cbfee61a-b7f7e6d000005936-f9-52ab38334843 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, linux-samsung-soc@vger.kernel.org Subject: [PATCH v11 5/7] Documentation:cpufreq:boost: Update BOOST documentation Date: Fri, 13 Dec 2013 17:38:35 +0100 Message-id: <1386952717-30947-6-git-send-email-l.majewski@samsung.com> X-Mailer: git-send-email 1.7.10.4 In-reply-to: <1386952717-30947-1-git-send-email-l.majewski@samsung.com> References: <1370502472-7249-1-git-send-email-l.majewski@samsung.com> <1386952717-30947-1-git-send-email-l.majewski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrILMWRmVeSWpSXmKPExsVy+t9jQV1ji9VBBrtfcFtsnLGe1eJp0w92 i76fV5gt1uz/yWTRefYJs8WbR9wWbx5uZrS4vGsOm8Xn3iOMFjPO72OyuN24gs3izOlLrBZP HvaxWWz86uHA57F4z0smjzvX9rB5rJv2ltljy9V2Fo++LasYPY7f2M7k8XmTXAB7FJdNSmpO Zllqkb5dAlfGhCsTWQquSFZc2dbD0sD4R6SLkZNDQsBEYtL25awQtpjEhXvr2UBsIYHpjBJr +5y6GLmA7C4mibX9DUwgCTYBPYnPd58ygSREBJYwSrxuWsAK4jALbGSW2DnzLVi7sECAxPGl h9hBbBYBVYmnb++AreAVcJPo37aRBWKdokT3swlg9ZwC7hLTNq1ihFjXxCjx/Mp9xgmMvAsY GVYxiqYWJBcUJ6XnGuoVJ+YWl+al6yXn525iBAfsM6kdjCsbLA4xCnAwKvHwevSuChJiTSwr rsw9xCjBwawkwhuiujpIiDclsbIqtSg/vqg0J7X4EKM0B4uSOO+BVutAIYH0xJLU7NTUgtQi mCwTB6dUA+OORt9mJbasKc8k1KOvd398XG4Ztu5+ue9RnjOyx2snBPXxTUiaW8F9hrPZ6f7M ujOzcjK3fy7MzTvWceRqh+pEm+UPhXi/Xr6tY5HU5raH99Ds9sC1VzfnLjjL7G+RO/tH56Gq b/V6jz0/GK74EbCURSH6LqOnx95anbADSnfS2d9Yd27Zt0SJpTgj0VCLuag4EQD6cLH9VAIA AA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 v11: - None 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 -- 1.7.10.4