From patchwork Mon Oct 14 12:17:49 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Majewski X-Patchwork-Id: 3035941 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 634E69F2B7 for ; Mon, 14 Oct 2013 12:20:36 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 27BC020219 for ; Mon, 14 Oct 2013 12:20:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D96152017A for ; Mon, 14 Oct 2013 12:20:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756446Ab3JNMUN (ORCPT ); Mon, 14 Oct 2013 08:20:13 -0400 Received: from mailout3.samsung.com ([203.254.224.33]:35803 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756179Ab3JNMTG (ORCPT ); Mon, 14 Oct 2013 08:19:06 -0400 Received: from epcpsbgm2.samsung.com (epcpsbgm2 [203.254.230.27]) by mailout3.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MUN004SIRJMD990@mailout3.samsung.com>; Mon, 14 Oct 2013 21:19:05 +0900 (KST) X-AuditID: cbfee61b-b7f776d0000016c8-9b-525be139879c Received: from epmmp1.local.host ( [203.254.227.16]) by epcpsbgm2.samsung.com (EPCPMTA) with SMTP id 90.8B.05832.931EB525; Mon, 14 Oct 2013 21:19:05 +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 <0MUN002FARIAL360@mmp1.samsung.com>; Mon, 14 Oct 2013 21:19:05 +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 Subject: [PATCH v9 6/7] Documentation:cpufreq:boost: Update BOOST documentation Date: Mon, 14 Oct 2013 14:17:49 +0200 Message-id: <1381753070-2853-7-git-send-email-l.majewski@samsung.com> X-Mailer: git-send-email 1.7.10 In-reply-to: <1381753070-2853-1-git-send-email-l.majewski@samsung.com> References: <1370502472-7249-1-git-send-email-l.majewski@samsung.com> <1381753070-2853-1-git-send-email-l.majewski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrNLMWRmVeSWpSXmKPExsVy+t9jAV3Lh9FBBmvPiFlsnLGe1eJp0w92 i76fV5gt1uz/yWTRefYJs8WbR9wWbx5uZrS4vGsOm8Xn3iOMFrcbV7BZnDl9idXiycM+NouN Xz0ceD0W73nJ5HHn2h42j3XT3jJ7bLnazuLRt2UVo8fxG9uZPD5vkgtgj+KySUnNySxLLdK3 S+DKaH79mb1gjmTFuf/djA2M10S6GDk4JARMJPb1eXcxcgKZYhIX7q1n62Lk4hASWMQo8efX EVYIp4tJou3lQxaQKjYBPYnPd58ygSREBJYwSrxuWgBWxSzQwyxx/Pp2NpCxwgL+Er8+GoE0 sAioSjw994MNxOYVcJVY8uwiK8Q6eYmn9/vA4pwCbhKntm1ghtjWyCix7dwG1gmMvAsYGVYx iqYWJBcUJ6XnGukVJ+YWl+al6yXn525iBAfpM+kdjKsaLA4xCnAwKvHwCjhFBwmxJpYVV+Ye YpTgYFYS4f14FSjEm5JYWZValB9fVJqTWnyIUZqDRUmc92CrdaCQQHpiSWp2ampBahFMlomD U6qB0fJqee2ztELX1uL1ltNZPHbuE39eEjbBa+2D8M/tD+ozpqi5mT/v2XxmD+vsTcWsuvlS F1cIHPnG4ioacaJ5AatbV1VlYU1Yp/fHzv2V+tu+HOepyPq582+2WF6p/OqNgW187lw5D05M 37v3yW/LFpGzCVMiebZa6eZ+nGaYbbjz/6vzrIc+KrEUZyQaajEXFScCANxa2ThOAgAA Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Spam-Status: No, score=-7.4 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 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