Messages in this thread | | | Date | Tue, 30 May 2023 12:02:11 +0200 | Subject | Re: [PATCH v2 09/17] PM: EM: Add RCU mechanism which safely cleans the old data | From | Dietmar Eggemann <> |
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On 12/05/2023 11:57, Lukasz Luba wrote: > The EM is going to support runtime modifications of the power data. > In order to achieve that prepare the internal mechanism. This patch > introduces RCU safe mechanism to clean up the old allocated EM data.
s/In order to achieve that prepare the internal mechanism. This patch introduces/Introduce ... much shorter, same information.
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> +static void em_perf_runtime_table_set(struct device *dev, > + struct em_perf_table *runtime_table) > +{ > + struct em_perf_domain *pd = dev->em_pd; > + struct em_perf_table *tmp; > + > + tmp = pd->runtime_table; > + > + rcu_assign_pointer(pd->runtime_table, runtime_table); > + > + em_cpufreq_update_efficiencies(dev, runtime_table->state); > + > + if (trace_em_perf_state_enabled()) { > + unsigned long freq, power, cost, flags; > + int i; > + > + for (i = 0; i < pd->nr_perf_states; i++) { > + freq = runtime_table->state[i].frequency; > + power = runtime_table->state[i].power; > + cost = runtime_table->state[i].cost; > + flags = runtime_table->state[i].flags; > + > + trace_em_perf_state(dev_name(dev), pd->nr_perf_states, > + i, freq, power, cost, flags); > + } > + } > + > + /* > + * Check if the 'state' array is not actually the one from setup. > + * If it is then don't free it. > + */ > + if (tmp->state == pd->table)
It's unfortunate that you have the refactoring in 13/17 which would lead to:
if (pd->runtime_table>state == pd->default_table->state) ^^^^^^^^^^^^^ ^^^^^^^^^^^^^
so people would immediately grasp one of the core concepts of the design: non-modifiable default_table and modifiable runtime_table.
I still belief that it would be the better idea to do the refactoring first.
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