From patchwork Fri Oct 21 16:14:24 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: srinivas pandruvada X-Patchwork-Id: 9389597 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 0DBF660762 for ; Fri, 21 Oct 2016 16:14:41 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 00C7A2A199 for ; Fri, 21 Oct 2016 16:14:41 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EA0DA2A1A9; Fri, 21 Oct 2016 16:14:40 +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 4CE272A199 for ; Fri, 21 Oct 2016 16:14:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934754AbcJUQOj (ORCPT ); Fri, 21 Oct 2016 12:14:39 -0400 Received: from mga06.intel.com ([134.134.136.31]:11147 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934420AbcJUQOi (ORCPT ); Fri, 21 Oct 2016 12:14:38 -0400 Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga104.jf.intel.com with ESMTP; 21 Oct 2016 09:14:37 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,377,1473145200"; d="scan'208";a="22202016" Received: from gagi.amr.corp.intel.com (HELO spandruv-mobl.jf.intel.com) ([10.252.133.114]) by fmsmga005.fm.intel.com with ESMTP; 21 Oct 2016 09:14:36 -0700 From: Srinivas Pandruvada To: rjw@rjwysocki.net Cc: linux-pm@vger.kernel.org, Srinivas Pandruvada Subject: [PATCH v2 2/4] cpufreq: intel_pstate: Reduce impact due to rounding error Date: Fri, 21 Oct 2016 09:14:24 -0700 Message-Id: <1477066466-22367-3-git-send-email-srinivas.pandruvada@linux.intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1477066466-22367-1-git-send-email-srinivas.pandruvada@linux.intel.com> References: <1477066466-22367-1-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 When policy->max and policy->min are same, in some cases they don't result in the same frequency cap. The max_policy_pct is rounded up but not min_perf_pct. So even when they are same, results in different percentage or maximum and minimum. Since minimum is a conservative value for power, a lower value without rounding is better in most of the cases, unless user wants policy->max = policy->min. This change uses use the same policy percentage when policy->max and policy->min are same. Signed-off-by: Srinivas Pandruvada --- drivers/cpufreq/intel_pstate.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index 98db507..1205d74 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -1546,11 +1546,17 @@ static void intel_pstate_set_performance_limits(struct perf_limits *limits) static void intel_pstate_update_perf_limits(struct cpufreq_policy *policy, struct perf_limits *limits) { - limits->min_policy_pct = (policy->min * 100) / policy->cpuinfo.max_freq; - limits->min_policy_pct = clamp_t(int, limits->min_policy_pct, 0, 100); limits->max_policy_pct = DIV_ROUND_UP(policy->max * 100, policy->cpuinfo.max_freq); limits->max_policy_pct = clamp_t(int, limits->max_policy_pct, 0, 100); + if (policy->max == policy->min) { + limits->min_policy_pct = limits->max_policy_pct; + } else { + limits->min_policy_pct = (policy->min * 100) / + policy->cpuinfo.max_freq; + limits->min_policy_pct = clamp_t(int, limits->min_policy_pct, + 0, 100); + } /* Normalize user input to [min_policy_pct, max_policy_pct] */ limits->min_perf_pct = max(limits->min_policy_pct,