Messages in this thread | | | Subject | Re: [PATCH v6 04/10] PM / EM: add support for other devices than CPUs in Energy Model | From | Lukasz Luba <> | Date | Fri, 10 Apr 2020 12:34:56 +0100 |
| |
On 4/10/20 12:12 PM, Luis Gerhorst wrote: > > Lukasz Luba writes: > >> +/** >> + * em_dev_unregister_perf_domain() - Unregister Energy Model (EM) for >> a device >> + * @dev : Device for which the EM is registered >> + * >> + * Try to unregister the EM for the specified device (it checks current >> + * reference counter). The EM for CPUs will not be freed. >> + */ >> +void em_dev_unregister_perf_domain(struct device *dev) >> +{ >> + struct em_device *em_dev, *tmp; >> + >> + if (IS_ERR_OR_NULL(dev)) >> + return; >> + >> + /* We don't support freeing CPU structures in hotplug */ >> + if (_is_cpu_device(dev)) { >> + dev_dbg_once(dev, "EM: the structures are not going to be >> removed\n"); >> + return; >> + } >> + >> + mutex_lock(&em_pd_mutex); >> + >> + if (list_empty(&em_pd_dev_list)) { >> + mutex_unlock(&em_pd_mutex); >> + return; >> + } >> + >> + list_for_each_entry_safe(em_dev, tmp, &em_pd_dev_list, >> em_dev_list) { >> + if (em_dev->dev == dev) { >> + kref_put(&em_dev->kref, _em_release); >> + break; >> + } >> + } >> + >> + mutex_unlock(&em_pd_mutex); >> +} >> +EXPORT_SYMBOL_GPL(em_dev_unregister_perf_domain); > > Ok, so em_dev_unregister_perf_domain() does not support the CPU device > and a subsequent em_register_perf_domain() will fail with EEXIST.
Correct. At the current mainline Energy Model we don't even have em_unregister_perf_domain function. I had to introduce it in order to support other devices which might have drivers loaded/unloaded as modules.
> > Is there a way to unregister/change the CPU's energy model during > runtime without restarting the whole system?
Not for the CPU for now.
It is possible for other devices. When you have i.e. a module driver for a device and in your code there is a (*active_power)(), then it is possible to change EM by unloading/loading the module.
For the CPU we don't have this requirement for production code. I will add you to CC list when something like this would pop-up for a prototyping/experimentation code. We have been analyzing some options.
Regards, Lukasz
| |