Commit 466a2b42 authored by Joel Fernandes's avatar Joel Fernandes Committed by Rafael J. Wysocki
Browse files

cpufreq: schedutil: Use idle_calls counter of the remote CPU 



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.

Fixes: 674e7541 (sched: cpufreq: Allow remote cpufreq callbacks)
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarJoel Fernandes <joelaf@google.com>
Cc: 4.14+ <stable@vger.kernel.org> # 4.14+
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 464e1d5f

include/linux/tick.h

+1 −0
Original line number Diff line number Diff line
@@ -119,6 +119,7 @@ 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 */

kernel/sched/cpufreq_schedutil.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

kernel/time/tick-sched.c

+13 −0
Original line number Diff line number Diff line
@@ -985,6 +985,19 @@ 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

 *

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