Since the recent remote cpufreq callback work, its possible that a cpufreq update is triggered from a remote CPU. For single policies however, the current code uses the local CPU when trying to determine if the remote sg_cpu entered idle or is busy. This is incorrect. To remedy this, compare with the nohz tick idle_calls counter of the remote CPU.
Cc: Rafael J. Wysocki rjw@rjwysocki.net Cc: Viresh Kumar viresh.kumar@linaro.org Cc: Ingo Molnar mingo@redhat.com Cc: Peter Zijlstra peterz@infradead.org Cc: Frederic Weisbecker fweisbec@gmail.com Cc: Thomas Gleixner tglx@linutronix.de Signed-off-by: Joel Fernandes joelaf@google.com --- include/linux/tick.h | 1 + kernel/sched/cpufreq_schedutil.c | 2 +- kernel/time/tick-sched.c | 13 +++++++++++++ 3 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/include/linux/tick.h b/include/linux/tick.h index fe01e68bf520..31bf2ae3e9a7 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -118,6 +118,7 @@ extern void tick_nohz_idle_exit(void); extern void tick_nohz_irq_exit(void); extern ktime_t tick_nohz_get_sleep_length(void); extern unsigned long tick_nohz_get_idle_calls(void); +extern unsigned long tick_nohz_get_idle_calls_cpu(int cpu); extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time); extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time); #else /* !CONFIG_NO_HZ_COMMON */ diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 9209d83ecdcf..1383aa9efb4f 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -244,7 +244,7 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, unsigned long *util, #ifdef CONFIG_NO_HZ_COMMON static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { - unsigned long idle_calls = tick_nohz_get_idle_calls(); + unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu); bool ret = idle_calls == sg_cpu->saved_idle_calls;
sg_cpu->saved_idle_calls = idle_calls; diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 7b258c59d78a..91d5e7be805b 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -1011,6 +1011,19 @@ ktime_t tick_nohz_get_sleep_length(void) return ts->sleep_length; }
+/** + * tick_nohz_get_idle_calls_cpu - return the current idle calls counter value + * for a particular CPU. + * + * Called from the schedutil frequency scaling governor in scheduler context. + */ +unsigned long tick_nohz_get_idle_calls_cpu(int cpu) +{ + struct tick_sched *ts = tick_get_tick_sched(cpu); + + return ts->idle_calls; +} + /** * tick_nohz_get_idle_calls - return the current idle calls counter value * -- 2.15.0.rc2.357.g7e34df9404-goog