Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933697AbbGUS4I (ORCPT ); Tue, 21 Jul 2015 14:56:08 -0400 Received: from mga09.intel.com ([134.134.136.24]:44633 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933338AbbGUS4F (ORCPT ); Tue, 21 Jul 2015 14:56:05 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,518,1432623600"; d="scan'208";a="610248409" Message-ID: <1437504822.2377.181.camel@spandruv-DESK3.jf.intel.com> Subject: Re: [PATCH RFC] intel_pstate: play well with frequency limits set by acpi From: Srinivas Pandruvada To: Konstantin Khlebnikov Cc: Konstantin Khlebnikov , linux-pm@vger.kernel.org, "Rafael J. Wysocki" , Linux Kernel Mailing List , linux-acpi@vger.kernel.org, Kristen Carlson Accardi , Len Brown , Ethan Zhao Date: Tue, 21 Jul 2015 11:53:42 -0700 In-Reply-To: <55AE7557.5010605@yandex-team.ru> References: <20150716181706.6500.64386.stgit@buzz> <1437084536.2377.117.camel@spandruv-DESK3.jf.intel.com> <1437426504.2377.162.camel@spandruv-DESK3.jf.intel.com> <55AE1DFC.3090209@yandex-team.ru> <1437493051.2377.170.camel@spandruv-DESK3.jf.intel.com> <55AE7557.5010605@yandex-team.ru> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4 (3.10.4-4.fc20) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3676 Lines: 72 On Tue, 2015-07-21 at 19:37 +0300, Konstantin Khlebnikov wrote: > On 21.07.2015 18:37, Srinivas Pandruvada wrote: > > On Tue, 2015-07-21 at 13:25 +0300, Konstantin Khlebnikov wrote: > >> 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. > > No, it can also be used in both ways. Once reduced, it can increase as > > well. _PPC can be dynamically modified by BIOS to reduce and also to > > increase. > > Well, in this case BIOS will trigger ACPI_PROCESSOR_NOTIFY_PERFORMANCE: > kernel evaluate new _PPC and call cpufreq_update_policy() > which set initial frequency min/max range according to user setup and > apply all limits after that. Initial policy->user_policy.min/max stay > unchanged. So, that dynamic modification works in both ways. > Fair enough. We need to take account for _PSS. We have some changes for this, but not gone through test cycle. I will post them as RFC, please check. Thanks for your patience. - Srinivas -- 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/