From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Chen Subject: Re: [PATCH v2 0/8] Support =?ISO-8859-1?Q?Intel=AE?= Turbo Boost Max Technology 3.0 Date: Fri, 16 Sep 2016 09:03:47 -0700 Message-ID: <1474041827.3916.92.camel@linux.intel.com> References: <1472762024-88771-1-git-send-email-srinivas.pandruvada@linux.intel.com> <20160915121430.GD13132@amd> <20160915134623.57596f86@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: Received: from mga09.intel.com ([134.134.136.24]:1380 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965037AbcIPQDt (ORCPT ); Fri, 16 Sep 2016 12:03:49 -0400 In-Reply-To: <20160915134623.57596f86@lxorguk.ukuu.org.uk> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: One Thousand Gnomes , Pavel Machek Cc: Srinivas Pandruvada , rjw@rjwysocki.net, tglx@linutronix.de, mingo@redhat.com, bp@suse.de, peterz@infradead.org, x86@kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org On Thu, 2016-09-15 at 13:46 +0100, One Thousand Gnomes wrote: > On Thu, 15 Sep 2016 14:14:30 +0200 > Pavel Machek wrote: > > > > > Hi! > > > > > > > > - Feature is enabled by default for single socket systems > > > > > > With Intel® Turbo Boost Max Technology 3.0 (ITMT), single-threaded performance is > > > optimized by identifying processor's fastest core and running critical workloads > > > on it. > > > Refere to: > > > http://www.intel.com/content/www/us/en/architecture-and-technology/turbo-boost/turbo-boost-max-technology.html   > > That does not really explain much. > > > > How does it work? Do the different cores have different max > > frequencies due to manufacturing differences? Ot is it running the > > workload on coldest core? > That's all down to the CPU, not architectural and may change. > > The ACPI tables describe which cores to use, whether that relates to > manufacturing, positioning or whatever isn't exposed. Please refer to patches  acpi: Enable HWP CPPC objects  acpi: bus: Set _OSC for diverse core support cpufreq: intel_pstate: Use CPPC to get max performance for how the differences in core's capabilities are exposed to OS. The asymmetric packing feature in the scheduler defines an order of which core should be scheduled with a load first. By using this feature, we can put load first on  the core that can be boosted to the highest frequency. Tim