From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [RFC/RFT] [PATCH 02/10] cpufreq: intel_pstate: Conditional frequency invariant accounting Date: Thu, 17 May 2018 18:16:49 +0200 Message-ID: <20180517161649.GX12217@hirez.programming.kicks-ass.net> References: <20180516044911.28797-1-srinivas.pandruvada@linux.intel.com> <20180516044911.28797-3-srinivas.pandruvada@linux.intel.com> <20180516151925.GO28366@localhost.localdomain> <20180516154733.GF12198@hirez.programming.kicks-ass.net> <20180516163105.GP28366@localhost.localdomain> <20180517105907.GC22493@localhost.localdomain> <20180517150418.GF22493@localhost.localdomain> <1526571692.11765.10.camel@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1526571692.11765.10.camel@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org To: Srinivas Pandruvada Cc: Juri Lelli , tglx@linutronix.de, mingo@redhat.com, bp@suse.de, lenb@kernel.org, rjw@rjwysocki.net, mgorman@techsingularity.net, x86@kernel.org, linux-pm@vger.kernel.org, viresh.kumar@linaro.org, linux-kernel@vger.kernel.org List-Id: linux-pm@vger.kernel.org On Thu, May 17, 2018 at 08:41:32AM -0700, Srinivas Pandruvada wrote: > One more point to note. Even if we calculate some utilization based on > the freq-invariant and arrive at a P-state, we will not be able to > control any P-state in turbo region (not even as a cap) on several > Intel processors using PERF_CTL MSRs. Right, but don't we need to set the PERF_CTL to max P in order to access the turbo bins? So we still need to compute a P state, but as soon as we reach max P, we're done. And its not as if setting anything below max P is a firm setting either anyway, its hints all the way down.