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cpufreq: schedutil: Use idle_calls counter of the remote CPU

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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: 674e75411f (sched: cpufreq: Allow remote cpufreq callbacks)
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Joel Fernandes <joelaf@google.com>
Cc: 4.14+ <stable@vger.kernel.org> # 4.14+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Joel Fernandes 2017-12-21 02:22:45 +01:00 committed by Rafael J. Wysocki
parent 464e1d5f23
commit 466a2b42d6
3 changed files with 15 additions and 1 deletions
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1
include/linux/tick.h
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@ -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 */

2
kernel/sched/cpufreq_schedutil.c
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@ -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;

13
kernel/time/tick-sched.c
View File

@ -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
*