From patchwork Fri Nov 16 22:24:20 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: srinivas pandruvada X-Patchwork-Id: 10687095 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-2.web.codeaurora.org (Postfix) with ESMTP id 3B6BB14D6 for ; Fri, 16 Nov 2018 22:24:46 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2AE0A2D891 for ; Fri, 16 Nov 2018 22:24:46 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1F16A2D89A; Fri, 16 Nov 2018 22:24:46 +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=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, 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 B9FFC2D897 for ; Fri, 16 Nov 2018 22:24:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726040AbeKQIiu (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-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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.