From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB054C433F5 for ; Mon, 4 Apr 2022 16:01:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378886AbiDDQDP (ORCPT ); Mon, 4 Apr 2022 12:03:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36996 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378808AbiDDQCq (ORCPT ); Mon, 4 Apr 2022 12:02:46 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 5AA4A245A5; Mon, 4 Apr 2022 09:00:50 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E3756D6E; Mon, 4 Apr 2022 09:00:49 -0700 (PDT) Received: from localhost (ionvoi01-desktop.cambridge.arm.com [10.1.196.65]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 888053F73B; Mon, 4 Apr 2022 09:00:49 -0700 (PDT) Date: Mon, 4 Apr 2022 17:00:47 +0100 From: Ionela Voinescu To: Lukasz Luba Cc: linux-kernel@vger.kernel.org, dietmar.eggemann@arm.com, Pierre.Gondois@arm.com, viresh.kumar@linaro.org, rafael@kernel.org, daniel.lezcano@linaro.org, linux-pm@vger.kernel.org, mka@chromium.org, nm@ti.com, sboyd@kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, cristian.marussi@arm.com, sudeep.holla@arm.com, matthias.bgg@gmail.com Subject: Re: [RESEND][PATCH 1/8] PM: EM: Add .get_cost() callback Message-ID: References: <20220321095729.20655-1-lukasz.luba@arm.com> <20220321095729.20655-2-lukasz.luba@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220321095729.20655-2-lukasz.luba@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Monday 21 Mar 2022 at 09:57:22 (+0000), Lukasz Luba wrote: > The Energy Model (EM) supports devices which report abstract power scale, > not only real Watts. The primary goal for EM is to enable the Energy Aware > Scheduler (EAS) for a given platform. Some of the platforms might not be > able to deliver proper power values. The only information that they might > have is the relative efficiency between CPU types. > > Thus, it makes sense to remove some restrictions in the EM framework and > introduce a mechanism which would support those platforms. What is crucial > for EAS to operate is the 'cost' field in the EM. The 'cost' is calculated > internally in EM framework based on knowledge from 'power' values. > The 'cost' values must be strictly increasing. The existing API with its > 'power' value size restrictions cannot guarantee that the 'cost' will meet > this requirement. > > Since the platform is missing this detailed information, but has only > efficiency details, introduce a new custom callback in the EM framework. > The new callback would allow to provide the 'cost' values which reflect > efficiency of the CPUs. This would allow to provide EAS information which > has different relation than what would be forced by the EM internal > formulas calculating 'cost' values. Thanks to this new callback it is > possible to create a system view for EAS which has no overlapping > performance states across many Performance Domains. > > Signed-off-by: Lukasz Luba > --- > include/linux/energy_model.h | 24 +++++++++++++++++++++++- > 1 file changed, 23 insertions(+), 1 deletion(-) > > diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h > index 9f3c400bc52d..0a3a5663177b 100644 > --- a/include/linux/energy_model.h > +++ b/include/linux/energy_model.h > @@ -114,9 +114,30 @@ struct em_data_callback { > */ > int (*active_power)(unsigned long *power, unsigned long *freq, > struct device *dev); > + > + /** > + * get_cost() - Provide the cost at the given performance state of > + * a device > + * @dev : Device for which we do this operation (can be a CPU) > + * @freq : Frequency at the performance state in kHz > + * @cost : The cost value for the performance state > + * (modified) > + * > + * In case of CPUs, the cost is the one of a single CPU in the domain. > + * It is expected to fit in the [0, EM_MAX_POWER] range due to internal > + * usage in EAS calculation. > + * > + * Return 0 on success, or appropriate error value in case of failure. > + */ > + int (*get_cost)(struct device *dev, unsigned long freq, > + unsigned long *cost); > }; > -#define EM_DATA_CB(_active_power_cb) { .active_power = &_active_power_cb } > #define EM_SET_ACTIVE_POWER_CB(em_cb, cb) ((em_cb).active_power = cb) > +#define EM_ADV_DATA_CB(_active_power_cb, _cost_cb) \ > + { .active_power = _active_power_cb, \ > + .get_cost = _cost_cb } > +#define EM_DATA_CB(_active_power_cb) \ > + EM_ADV_DATA_CB(_active_power_cb, NULL) > > struct em_perf_domain *em_cpu_get(int cpu); > struct em_perf_domain *em_pd_get(struct device *dev); > @@ -264,6 +285,7 @@ static inline int em_pd_nr_perf_states(struct em_perf_domain *pd) > > #else > struct em_data_callback {}; > +#define EM_ADV_DATA_CB(_active_power_cb, _cost_cb) { } > #define EM_DATA_CB(_active_power_cb) { } > #define EM_SET_ACTIVE_POWER_CB(em_cb, cb) do { } while (0) > Reviewed-by: Ionela Voinescu Thanks, Ionela. > -- > 2.17.1 >