From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Herrmann Subject: Re: Commit 554c8aa8ecad causing severe performance degression with pcc-cpufreq Date: Tue, 17 Jul 2018 11:11:52 +0200 Message-ID: <20180717091152.l4ixicbp6imvqtsr@suselix> References: <20180717065048.74mmgk4t5utjaa6a@suselix> <20180717085039.kqxwbkgruhj5qxtx@suselix> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: "Rafael J. Wysocki" Cc: "Rafael J. Wysocki" , Peter Zijlstra , Frederic Weisbecker , Viresh Kumar , Linux PM , Linux Kernel Mailing List List-Id: linux-pm@vger.kernel.org On Tue, Jul 17, 2018 at 11:06:29AM +0200, Rafael J. Wysocki wrote: > On Tue, Jul 17, 2018 at 10:50 AM, Andreas Herrmann wrote: > > [cut] > > > > > On balance before this commit users could use pcc-cpufreq but had > > already suboptimal performance (compared to say intel_pstate driver > > which can be used changing BIOS options). > > BTW, I wonder why you need to change the BIOS options for intel_pstate to load. I think this is because of (in intel_pstate_init()): /* * The Intel pstate driver will be ignored if the platform * firmware has its own power management modes. */ if (intel_pstate_platform_pwr_mgmt_exists()) return -ENODEV; > It should be initialized before pcc-cpufreq (according to their > respective initcall levels), so in theory intel_pstate should be used > by default on the affected systems anyway. > What BIOS settings need to be changed for that? Already answered in other mail. Andreas