From patchwork Tue Dec 6 21:32:17 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Srinivas Pandruvada X-Patchwork-Id: 9463289 X-Patchwork-Delegate: rjw@sisk.pl Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 85B2B60231 for ; Tue, 6 Dec 2016 21:32:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 779B02835E for ; Tue, 6 Dec 2016 21:32:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6C7E628428; Tue, 6 Dec 2016 21:32:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1E5282835E for ; Tue, 6 Dec 2016 21:32:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752105AbcLFVcr (ORCPT ); Tue, 6 Dec 2016 16:32:47 -0500 Received: from mga04.intel.com ([192.55.52.120]:30593 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752037AbcLFVcq (ORCPT ); Tue, 6 Dec 2016 16:32:46 -0500 Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga104.fm.intel.com with ESMTP; 06 Dec 2016 13:32:20 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,310,1477983600"; d="scan'208";a="1078373911" Received: from spandruv-desk.jf.intel.com ([10.54.75.13]) by fmsmga001.fm.intel.com with ESMTP; 06 Dec 2016 13:32:19 -0800 From: Srinivas Pandruvada To: lenb@kernel.org, rjw@rjwysocki.net Cc: linux-pm@vger.kernel.org, Srinivas Pandruvada Subject: [PATCH v2 3/3] Documentation: intel_pstate: Add energy performance hint Date: Tue, 6 Dec 2016 13:32:17 -0800 Message-Id: <1481059937-193048-4-git-send-email-srinivas.pandruvada@linux.intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1481059937-193048-1-git-send-email-srinivas.pandruvada@linux.intel.com> References: <1481059937-193048-1-git-send-email-srinivas.pandruvada@linux.intel.com> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Updated documentation for the support of energy performance hint. Signed-off-by: Srinivas Pandruvada --- Documentation/cpu-freq/intel-pstate.txt | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/Documentation/cpu-freq/intel-pstate.txt b/Documentation/cpu-freq/intel-pstate.txt index 198b2ef..012170e 100644 --- a/Documentation/cpu-freq/intel-pstate.txt +++ b/Documentation/cpu-freq/intel-pstate.txt @@ -139,6 +139,30 @@ architecture of the processor permits: - User can read write system wide turbo status /sys/devices/system/cpu/no_turbo +Support of energy performance hint +It is possible to provide hints to the HWP algorithms in the processor +to be more performance centric to more energy centric. When driver is +using HWP, two additional cpufreq sysfs attributes are presented for +each logical CPU. +These attributes are: + - energy_performance_available_preferences + - energy_performance_preference + +To get list of supported hints: +$ cat energy_performance_available_preferences + default performance balance_performance balance_power power + +The current preference can be read or changed via cpufreq sysfs +attribute "energy_performance_preference". Reading from this attribute +will display current effective setting. User can write any of the valid +preference string to this attribute. User can always restore to power-on +default by writing "default". + +Since threads can migrate to different CPUs, this is possible that the +new CPU may have different energy performance preference than the previous +one. To avoid such issues, either threads can be pinned to specific CPUs +or set the same energy performance preference value to all CPUs. + Tuning Intel P-State driver When the performance can be tuned using PID (Proportional Integral