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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 10079C3F68F for ; Tue, 28 Jan 2020 07:46:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E59FE24681 for ; Tue, 28 Jan 2020 07:46:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725922AbgA1HqR (ORCPT ); Tue, 28 Jan 2020 02:46:17 -0500 Received: from mga07.intel.com ([134.134.136.100]:58075 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725825AbgA1HqR (ORCPT ); Tue, 28 Jan 2020 02:46:17 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 Jan 2020 23:46:14 -0800 X-IronPort-AV: E=Sophos;i="5.70,372,1574150400"; d="scan'208";a="308519690" Received: from vinayver-mobl1.gar.corp.intel.com ([10.252.174.80]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 Jan 2020 23:46:09 -0800 Message-ID: <6eba5e502636ec8a0be279f48097c7137a95aa13.camel@linux.intel.com> Subject: Re: [PATCH v2] admin guide/pm: Admin guide for Intel Uncore Frequency limits From: Srinivas Pandruvada To: Jonathan Corbet Cc: andy@infradead.org, dvhart@infradead.org, lenb@kernel.org, andy@kernel.org, linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-doc@vger.kernel.org Date: Mon, 27 Jan 2020 23:46:02 -0800 In-Reply-To: <20200124100039.70116459@lwn.net> References: <20200113040143.1419770-1-srinivas.pandruvada@linux.intel.com> <20200124100039.70116459@lwn.net> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.1-2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2020-01-24 at 10:00 -0700, Jonathan Corbet wrote: > On Sun, 12 Jan 2020 20:01:43 -0800 > Srinivas Pandruvada wrote: > > > Added documentation for the attributes to control uncore frequency > > selection. > > > > Signed-off-by: Srinivas Pandruvada < > > srinivas.pandruvada@linux.intel.com> > > --- > > v2: > > - Split the documentation patch to another patch to merge via > > different > > tree > > Which tree did you have in mind? PM stuff tends to go through > Rafael's > tree, normally, which is fine. Linux PM tree is fine. I will add necessary --to and --cc to my next version of the patch with the suggested changes from you. Thanks, Srinivas > > > Documentation/admin-guide/pm/intel_uncore.rst | 23 > > +++++++++++++++++++ > > .../admin-guide/pm/working-state.rst | 1 + > > 2 files changed, 24 insertions(+) > > create mode 100644 Documentation/admin-guide/pm/intel_uncore.rst > > > > diff --git a/Documentation/admin-guide/pm/intel_uncore.rst > > b/Documentation/admin-guide/pm/intel_uncore.rst > > new file mode 100644 > > index 000000000000..d75be65fb16a > > --- /dev/null > > +++ b/Documentation/admin-guide/pm/intel_uncore.rst > > @@ -0,0 +1,23 @@ > > +.. SPDX-License-Identifier: GPL-2.0 > > + > > +========================================================= > > +Intel® Uncore Frequency Selection > > I would really like to avoid adding ® symbols throughout the docs. I > get > grief for non-ASCII symbols that actually have a need to be there; > this > isn't one of those. > > > +========================================================= > > + > > +The uncore frequency in the Intel(R) hardware is selected based on > > internal heuristics, which uses the current selected performance > > state and various system power constraints. In majority of the > > cases this selection is the most optimal, so there is no need for > > placing external constraints from the Operating System. > > I would say that this violates the 80-character limit by a character > or > two... The entire patch has this problem. > > > + > > +But there are some customers who wants less jitters from dynamic > > uncore frequency selection. For them, power saving is much lower > > priority than consistent performance. Currently these customers > > uses MSR 0x620, to place hard limits on the maximum and the minimum > > uncore frequency. They can now use Linux sysfs to place these > > limits and also have additional capability to place hard limits > > under power constraint scenario. > > less jitter (singular) > > > + > > +The Uncore frequency section attributes are present under > > "/sys/devices/system/cpu/intel_uncore_frequency". > > +The scope of these attributes is per die in multi-die systems or > > package wide in non multi-die systems. There is a unique folder for > > each die or package. For example: > > +"package_00_die_00" for package 0 and die 0. > > This may not render as you would like; use an RST literal block here. > > Thanks, > > jon >