2019-05-08 20:00:50

by Douglas RAILLARD

[permalink] [raw]
Subject: [RFC PATCH 5/7] sched/cpufreq: sugov_cpu_is_busy for shared policy

From: Douglas RAILLARD <[email protected]>

Allow using sugov_cpu_is_busy() from sugov_update_shared(). This means
that the heuristic needs to return stable results across multiple calls
for a given CPU, even if there has been no utilization change since last
call.

sugov_cpu_is_busy() currently both checks business status and updates
the counters, so let's decouple the two actions.

Signed-off-by: Douglas RAILLARD <[email protected]>
---
kernel/sched/cpufreq_schedutil.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index a52c66559321..a12b7e5bc028 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -178,12 +178,17 @@ static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
{
unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
bool ret = idle_calls == sg_cpu->saved_idle_calls;
+ return ret;
+}

+static void sugov_cpu_is_busy_update(struct sugov_cpu *sg_cpu)
+{
+ unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
sg_cpu->saved_idle_calls = idle_calls;
- return ret;
}
#else
static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
+static void sugov_cpu_is_busy_update(struct sugov_cpu *sg_cpu) {}
#endif /* CONFIG_NO_HZ_COMMON */

/**
@@ -503,6 +508,7 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
return;

busy = sugov_cpu_is_busy(sg_cpu);
+ sugov_cpu_is_busy_update(sg_cpu);

util = sugov_get_util(sg_cpu);
max = sg_cpu->max;
--
2.21.0