From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 081B8C43441 for ; Fri, 16 Nov 2018 22:24:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C10EC2087C for ; Fri, 16 Nov 2018 22:24:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C10EC2087C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728039AbeKQIiu (ORCPT ); Sat, 17 Nov 2018 03:38:50 -0500 Received: from mga18.intel.com ([134.134.136.126]:20405 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725819AbeKQIiu (ORCPT ); Sat, 17 Nov 2018 03:38:50 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 Nov 2018 14:24:37 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,241,1539673200"; d="scan'208";a="96936490" Received: from spandruv-desk.jf.intel.com ([10.54.75.31]) by FMSMGA003.fm.intel.com with ESMTP; 16 Nov 2018 14:24:37 -0800 From: Srinivas Pandruvada To: lenb@kernel.org, rjw@rjwysocki.net, viresh.kumar@linaro.org, corbet@lwn.net Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, yu.c.chen@intel.com, Srinivas Pandruvada Subject: [PATCH 2/2] Documentation: intel_pstate: Clarify coordination of P-State limits Date: Fri, 16 Nov 2018 14:24:20 -0800 Message-Id: <20181116222420.24260-2-srinivas.pandruvada@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181116222420.24260-1-srinivas.pandruvada@linux.intel.com> References: <20181116222420.24260-1-srinivas.pandruvada@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Explain influence of per-core P-states and hyper threading on the effective performance. Signed-off-by: Srinivas Pandruvada --- Documentation/admin-guide/pm/intel_pstate.rst | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/pm/intel_pstate.rst b/Documentation/admin-guide/pm/intel_pstate.rst index ac6f5c597a56..ec0f7c111f65 100644 --- a/Documentation/admin-guide/pm/intel_pstate.rst +++ b/Documentation/admin-guide/pm/intel_pstate.rst @@ -495,7 +495,15 @@ on the following rules, regardless of the current operation mode of the driver: 2. Each individual CPU is affected by its own per-policy limits (that is, it cannot be requested to run faster than its own per-policy maximum and it - cannot be requested to run slower than its own per-policy minimum). + cannot be requested to run slower than its own per-policy minimum). The + effective performance depends on whether the platform supports per core + P-states, hyper-threading is enabled and on current performance requests + from other CPUs. When platform doesn't support per core P-states, the + effective performance can be more than the policy limits set on a CPU, if + other CPUs are requesting higher performance at that moment. Even with per + core P-states support, when hyper-threading is enabled, if the sibling CPU + is requesting higher performance, the other siblings will get higher + performance than their policy limits. 3. The global and per-policy limits can be set independently. -- 2.17.1