On 25-09-20, 09:21, Lukasz Luba wrote: > > > On 9/16/20 7:45 AM, Viresh Kumar wrote: > > In order to prepare for lock-less stats update, add support to defer any > > updates to it until cpufreq_stats_record_transition() is called. > > > > Signed-off-by: Viresh Kumar <[email protected]> > > --- > > drivers/cpufreq/cpufreq_stats.c | 75 ++++++++++++++++++++++++--------- > > 1 file changed, 56 insertions(+), 19 deletions(-) > > > > [snip] > > > @@ -228,10 +264,11 @@ void cpufreq_stats_record_transition(struct > > cpufreq_policy *policy, > > struct cpufreq_stats *stats = policy->stats; > > int old_index, new_index; > > - if (!stats) { > > - pr_debug("%s: No stats found\n", __func__); > > + if (!stats) > > return; > > - } > > + > > + if (READ_ONCE(stats->reset_pending)) > > + cpufreq_stats_reset_table(stats); > > This is in the hot path code, called from the scheduler. I wonder if we > avoid it or make that branch 'unlikely'? > > if (unlikely(READ_ONCE(stats->reset_pending))) > > Probably the CPU (when it has good prefetcher) would realize about it, > but maybe we can help a bit here.
Sure. -- viresh
