Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753737AbbGUKZH (ORCPT ); Tue, 21 Jul 2015 06:25:07 -0400 Received: from forward-corp1g.mail.yandex.net ([95.108.253.251]:51247 "EHLO forward-corp1g.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751842AbbGUKZF (ORCPT ); Tue, 21 Jul 2015 06:25:05 -0400 Authentication-Results: smtpcorp4.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Message-ID: <55AE1DFC.3090209@yandex-team.ru> Date: Tue, 21 Jul 2015 13:25:00 +0300 From: Konstantin Khlebnikov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Srinivas Pandruvada , Konstantin Khlebnikov CC: linux-pm@vger.kernel.org, "Rafael J. Wysocki" , Linux Kernel Mailing List , linux-acpi@vger.kernel.org, Kristen Carlson Accardi , Len Brown , Ethan Zhao Subject: Re: [PATCH RFC] intel_pstate: play well with frequency limits set by acpi References: <20150716181706.6500.64386.stgit@buzz> <1437084536.2377.117.camel@spandruv-DESK3.jf.intel.com> <1437426504.2377.162.camel@spandruv-DESK3.jf.intel.com> In-Reply-To: <1437426504.2377.162.camel@spandruv-DESK3.jf.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2612 Lines: 56 On 21.07.2015 00:08, Srinivas Pandruvada wrote: > On Fri, 2015-07-17 at 07:36 +0300, Konstantin Khlebnikov wrote: >> On Fri, Jul 17, 2015 at 1:08 AM, Srinivas Pandruvada >> wrote: >>> On Thu, 2015-07-16 at 21:17 +0300, Konstantin Khlebnikov wrote: >>>> IPMI can control CPU P-states remotely: configuration is reported via >>>> common ACPI interface (_PPC/_PSS/etc). This patch adds required minimal >>>> support in intel_pstate to receive and use these P-state limits. >>>> >>>> * ignore limit of top state in _PPC: it lower than turbo boost frequency >>>> * register intel_pstate in acpi-processor to get states from _PSS >>>> * link acpi_processor_get_bios_limit: this adds attribute "bios_limit" >>>> >>>> Signed-off-by: Konstantin Khlebnikov >>>> --- >>>> drivers/acpi/processor_perflib.c | 3 +- >>>> drivers/cpufreq/intel_pstate.c | 57 ++++++++++++++++++++++++++++++++++++++ >>>> 2 files changed, 59 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c >>>> index cfc8aba72f86..781e328c9d5f 100644 >>>> --- a/drivers/acpi/processor_perflib.c >>>> +++ b/drivers/acpi/processor_perflib.c >>>> @@ -98,7 +98,8 @@ static int acpi_processor_ppc_notifier(struct notifier_block *nb, >>>> >>>> ppc = (unsigned int)pr->performance_platform_limit; >>>> >>>> - if (ppc >= pr->performance->state_count) >>>> + /* Ignore limit of top state: it lower than turbo boost frequency */ >>>> + if (!ppc || ppc >= pr->performance->state_count) >>> Why? Isn't the previous check enough? >> >> Zero _PPC state must be top performance state but as I see frequency in >> _PSS is lower than maximum possible turbo frequency. So, in this case >> intel_pstate cannnot get "100%" for max bound even it there is no limit set. >> >> For example: I saw _PSS[0] = 2601 Mhz, PSS[1] = 2600 Mhz while turbo >> state is 3400 Mhz. >> > Have you tested dynamic _PPC modification with acpi cpufreq with this > change (after boot)? Suppose _PPC is changed from 3 to 0, then > cpufreq_verify_within_limits will not be called to change to new max > turbo performance state. > I haven't checked that but as I see acpi_processor_ppc_notifier() can only reduce maximum frequency. So, there should be no problem in this case. -- Konstantin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/