From patchwork Fri Sep 20 16:01:03 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Majewski X-Patchwork-Id: 2919571 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 977A6BFF05 for ; Fri, 20 Sep 2013 16:02:53 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id DB5BB2034A for ; Fri, 20 Sep 2013 16:02:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 94D7D20342 for ; Fri, 20 Sep 2013 16:02:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752251Ab3ITQCc (ORCPT ); Fri, 20 Sep 2013 12:02:32 -0400 Received: from mailout3.samsung.com ([203.254.224.33]:45254 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752900Ab3ITQCE (ORCPT ); Fri, 20 Sep 2013 12:02:04 -0400 Received: from epcpsbgm1.samsung.com (epcpsbgm1 [203.254.230.26]) by mailout3.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MTF000YVLUZ78G0@mailout3.samsung.com>; Sat, 21 Sep 2013 01:02:03 +0900 (KST) X-AuditID: cbfee61a-b7f7a6d00000235f-13-523c717ae34e Received: from epmmp1.local.host ( [203.254.227.16]) by epcpsbgm1.samsung.com (EPCPMTA) with SMTP id 06.B8.09055.A717C325; Sat, 21 Sep 2013 01:02:03 +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 <0MTF003RULTUIYB0@mmp1.samsung.com>; Sat, 21 Sep 2013 01:02:02 +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 , Myungjoo Ham , durgadoss.r@intel.com Subject: [PATCH RESEND v8 6/7] Documentation:cpufreq:boost: Update BOOST documentation Date: Fri, 20 Sep 2013 18:01:03 +0200 Message-id: <1379692864-4954-7-git-send-email-l.majewski@samsung.com> X-Mailer: git-send-email 1.7.10 In-reply-to: <1379692864-4954-1-git-send-email-l.majewski@samsung.com> References: <1370502472-7249-1-git-send-email-l.majewski@samsung.com> <1379692864-4954-1-git-send-email-l.majewski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrHLMWRmVeSWpSXmKPExsVy+t9jAd3qQpsgg5Yp7BYbZ6xntXja9IPd Yt5nWYu+n1eYLdbs/8lk0Xn2CbPFm0fcFm8ebma0uLxrDpvF594jjBa3G1ewWfQv7GWyePKw j81i41cPBz6PxXteMnncubaHzWPdtLfMHn1bVjF6PFrcwuhx/MZ2Jo/Pm+QC2KO4bFJSczLL Uov07RK4MlZfn8tY0ChZsWRmG3MD4xGRLkZODgkBE4kN1+4wQdhiEhfurWfrYuTiEBJYxCix evJ9Vgini0niwP+tLCBVbAJ6Ep/vPgXrEBGYwyhx56g7iM0ssItZ4tIlXRBbWCBC4uKsBkYQ m0VAVaLt4g72LkYODl4BV4ntk7UhlslLPL3fxwZicwq4STz+PI8FYlcjo8TbWYtYJzDyLmBk WMUomlqQXFCclJ5rqFecmFtcmpeul5yfu4kRHKrPpHYwrmywOMQowMGoxMPbEWQTJMSaWFZc mXuIUYKDWUmEt7YAKMSbklhZlVqUH19UmpNafIhRmoNFSZz3QKt1oJBAemJJanZqakFqEUyW iYNTqoHR3JPnkNfM2O5ZWyadmCAZu2FR/eVZs1/t9PrxYYXX45adwSWbvBy15jNfvC/7PneV wKOQTYkzbdPMGSxEbwT5CfDfVW/TNxSMUPwas+6565b3URkMYaJRXNJmcUtt5fqfMcjVvlrh /s9a/c7D6kNTHjl0buT0fTL5bcnaWGGtg2IeV63buwqVWIozEg21mIuKEwFSoXYsUQIAAA== Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Spam-Status: No, score=-7.6 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 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