Re: [RFC][PATCH v021 3/9] PM: EM: Move perf rebuilding function from schedutil to EM

Christian Loehle
2024-12-11T10:32:15Z

On 11/29/24 15:59, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> The sugov_eas_rebuild_sd() function defined in the schedutil cpufreq
> governor implements generic functionality that may be useful in other
> places. In particular, going forward it will be used in the intel_pstate
> driver.
>
> For this reason, move it from schedutil to the energy model code and
> rename it to em_rebuild_perf_domains().
>
> This also helps to get rid of some #ifdeffery in schedutil which is a
> plus.
>
> No intentional functional impact.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>
> v0.1 -> v0.2:
> * Update the comment regarding :register_em() in cpufreq.
> * Changelog edits.
>
> ---
> drivers/cpufreq/cpufreq.c | 2 +-
> include/linux/energy_model.h | 2 ++
> kernel/power/energy_model.c | 17 +++++++++++++++++
> kernel/sched/cpufreq_schedutil.c | 33 ++++++---------------------------
> 4 files changed, 26 insertions(+), 28 deletions(-)
>
> Index: linux-pm/kernel/power/energy_model.c
> ===================================================================
> --- linux-pm.orig/kernel/power/energy_model.c
> +++ linux-pm/kernel/power/energy_model.c
> @@ -908,3 +908,20 @@ int em_update_performance_limits(struct
> return 0;
> }
> EXPORT_SYMBOL_GPL(em_update_performance_limits);
> +
> +static void rebuild_sd_workfn(struct work_struct *work)
> +{
> + rebuild_sched_domains_energy();
> +}
> +
> +static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
> +
> +void em_rebuild_perf_domains(void)
> +{
> + /*
> + * When called from the cpufreq_register_driver() path, the
> + * cpu_hotplug_lock is already held, so use a work item to
> + * avoid nested locking in rebuild_sched_domains().
> + */
> + schedule_work(&rebuild_sd_work);
> +}
> Index: linux-pm/kernel/sched/cpufreq_schedutil.c
> ===================================================================
> --- linux-pm.orig/kernel/sched/cpufreq_schedutil.c
> +++ linux-pm/kernel/sched/cpufreq_schedutil.c
> @@ -604,31 +604,6 @@ static const struct kobj_type sugov_tuna
>
> /********************** cpufreq governor interface *********************/
>
> -#ifdef CONFIG_ENERGY_MODEL
> -static void rebuild_sd_workfn(struct work_struct *work)
> -{
> - rebuild_sched_domains_energy();
> -}
> -
> -static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
> -
> -/*
> - * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
> - * on governor changes to make sure the scheduler knows about it.
> - */
> -static void sugov_eas_rebuild_sd(void)
> -{
> - /*
> - * When called from the cpufreq_register_driver() path, the
> - * cpu_hotplug_lock is already held, so use a work item to
> - * avoid nested locking in rebuild_sched_domains().
> - */
> - schedule_work(&rebuild_sd_work);
> -}
> -#else
> -static inline void sugov_eas_rebuild_sd(void) { };
> -#endif
> -
> struct cpufreq_governor schedutil_gov;
>
> static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
> @@ -784,7 +759,11 @@ static int sugov_init(struct cpufreq_pol
> goto fail;
>
> out:
> - sugov_eas_rebuild_sd();
> + /*
> + * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
> + * on governor changes to make sure the scheduler knows about them.
> + */
> + em_rebuild_perf_domains();

The sugov mention might be considered stale after the next patch?
Apart from that LGTM.