On 02-11-17, 10:54, Chris Redpath wrote:
> Since:
>
> 4296f23ed cpufreq: schedutil: Fix per-CPU structure initialization in
> sugov_start()
Good catch but you pointed out to the wrong commit really.
674e75411fc2 ("sched: cpufreq: Allow remote cpufreq callbacks"
is the real culprit as that's where the 'cpu' field is added.
> We lost the value of sg_cpu->cpu which is assigned during
> sugov_register. The memset in sugov_start overwrites it with zero.
>
> This leads to always looking at the utilization of CPU0 instead of
> the one we just updated when we do a utilization update callback.
>
> Let's fix this by consolidating the initialization code into
> sugov_start().
>
> Fixes: 4296f23ed49a ("cpufreq: schedutil: Fix per-CPU structure initialization in sugov_start()")
Fixes: 674e75411fc2 ("sched: cpufreq: Allow remote cpufreq callbacks")
> Signed-off-by: Chris Redpath <chris.redpath@xxxxxxx>
> Reviewed-by: Patrick Bellasi <patrick.bellasi@xxxxxxx>
> Reviewed-by: Brendan Jackman <brendan.jackman@xxxxxxx>
> Cc: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
> Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: 4.9+ <stable@xxxxxxxxxxxxxxx>
This wouldn't be required now as it got merged in 4.14 only and Rafael
should be able to get that as part of 4.14 itself.
> ---
> kernel/sched/cpufreq_schedutil.c | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
> index 6c1a7fcfa2a7..eeb7e0a1d861 100644
> --- a/kernel/sched/cpufreq_schedutil.c
> +++ b/kernel/sched/cpufreq_schedutil.c
> @@ -731,6 +731,7 @@ static int sugov_start(struct cpufreq_policy *policy)
> sg_cpu->sg_policy = sg_policy;
> sg_cpu->flags = SCHED_CPUFREQ_RT;
> sg_cpu->iowait_boost_max = policy->cpuinfo.max_freq;
> + sg_cpu->cpu = cpu;
Maybe just move this below memset.
> }
>
> for_each_cpu(cpu, policy->cpus) {
> @@ -793,11 +794,6 @@ struct cpufreq_governor *cpufreq_default_governor(void)
>
> static int __init sugov_register(void)
> {
> - int cpu;
> -
> - for_each_possible_cpu(cpu)
> - per_cpu(sugov_cpu, cpu).cpu = cpu;
> -
> return cpufreq_register_governor(&schedutil_gov);
> }
> fs_initcall(sugov_register);
Diff looks fine though.
--
viresh