cpuidle: teo: Adjust handling of very short idle times

If the time till the next timer event is shorter than the target
residency of the first idle state (state 0), the TEO governor does
not update its metrics for any idle states, but arguably it should
record a "hit" for idle state 0 in that case, so modify it to do
that.

Accordingly, also make it record an "early hit" for idle state 0 if
the measured idle duration is less than its target residency, which
allows one branch more to be dropped from teo_update().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpuidle/governors/teo.c b/drivers/cpuidle/governors/teo.c
index 6deaaf5f05b5765598115132492edc4f654df9da..7dcfc9499910ca84a1a6bb9877e374f21f5f9010 100644 (file)
--- a/drivers/cpuidle/governors/teo.c
+++ b/drivers/cpuidle/governors/teo.c
@@ -117,7 +117,8 @@ static DEFINE_PER_CPU(struct teo_cpu, teo_cpus);
 static void teo_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 {
        struct teo_cpu *cpu_data = per_cpu_ptr(&teo_cpus, dev->cpu);
-       int i, idx_hit = -1, idx_timer = -1;
+       int i, idx_hit = 0, idx_timer = 0;
+       unsigned int hits, misses;
        u64 measured_ns;
 
        if (cpu_data->time_span_ns >= cpu_data->sleep_length_ns) {
@@ -174,25 +175,22 @@ static void teo_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
         * also increase the "early hits" metric for the state that actually
         * matches the measured idle duration.
         */
-       if (idx_timer >= 0) {
-               unsigned int hits = cpu_data->states[idx_timer].hits;
-               unsigned int misses = cpu_data->states[idx_timer].misses;
-
-               hits -= hits >> DECAY_SHIFT;
-               misses -= misses >> DECAY_SHIFT;
-
-               if (idx_timer > idx_hit) {
-                       misses += PULSE;
-                       if (idx_hit >= 0)
-                               cpu_data->states[idx_hit].early_hits += PULSE;
-               } else {
-                       hits += PULSE;
-               }
+       hits = cpu_data->states[idx_timer].hits;
+       hits -= hits >> DECAY_SHIFT;
+
+       misses = cpu_data->states[idx_timer].misses;
+       misses -= misses >> DECAY_SHIFT;
 
-               cpu_data->states[idx_timer].misses = misses;
-               cpu_data->states[idx_timer].hits = hits;
+       if (idx_timer == idx_hit) {
+               hits += PULSE;
+       } else {
+               misses += PULSE;
+               cpu_data->states[idx_hit].early_hits += PULSE;
        }
 
+       cpu_data->states[idx_timer].misses = misses;
+       cpu_data->states[idx_timer].hits = hits;
+
        /*
         * Save idle duration values corresponding to non-timer wakeups for
         * pattern detection.