[RFC][PATCH v2 3/5] cpuidle/teo: Simplify a little

From: Peter Zijlstra
Date: Wed Aug 02 2023 - 09:31:48 EST


Remove some of the early exit cases that rely on state_count, since we
have the additional tick state. Declutters some of the next patches, can
possibly be re-instated later if desired.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
drivers/cpuidle/governors/teo.c | 31 +------------------------------
1 file changed, 1 insertion(+), 30 deletions(-)

--- a/drivers/cpuidle/governors/teo.c
+++ b/drivers/cpuidle/governors/teo.c
@@ -187,7 +187,6 @@ struct teo_bin {
* @next_recent_idx: Index of the next @recent_idx entry to update.
* @recent_idx: Indices of bins corresponding to recent "intercepts".
* @util_threshold: Threshold above which the CPU is considered utilized
- * @utilized: Whether the last sleep on the CPU happened while utilized
*/
struct teo_cpu {
s64 time_span_ns;
@@ -197,7 +196,6 @@ struct teo_cpu {
int next_recent_idx;
int recent_idx[NR_RECENT];
unsigned long util_threshold;
- bool utilized;
};

static DEFINE_PER_CPU(struct teo_cpu, teo_cpus);
@@ -379,33 +377,6 @@ static int teo_select(struct cpuidle_dri
duration_ns = tick_nohz_get_sleep_length(&delta_tick);
cpu_data->sleep_length_ns = duration_ns;

- /* Check if there is any choice in the first place. */
- if (drv->state_count < 2) {
- idx = 0;
- goto end;
- }
- if (!dev->states_usage[0].disable) {
- idx = 0;
- if (drv->states[1].target_residency_ns > duration_ns)
- goto end;
- }
-
- cpu_data->utilized = teo_cpu_is_utilized(dev->cpu, cpu_data);
- /*
- * If the CPU is being utilized over the threshold and there are only 2
- * states to choose from, the metrics need not be considered, so choose
- * the shallowest non-polling state and exit.
- */
- if (drv->state_count < 3 && cpu_data->utilized) {
- for (i = 0; i < drv->state_count; ++i) {
- if (!dev->states_usage[i].disable &&
- !(drv->states[i].flags & CPUIDLE_FLAG_POLLING)) {
- idx = i;
- goto end;
- }
- }
- }
-
/*
* Find the deepest idle state whose target residency does not exceed
* the current sleep length and the deepest idle state not deeper than
@@ -541,7 +512,7 @@ static int teo_select(struct cpuidle_dri
* If the CPU is being utilized over the threshold, choose a shallower
* non-polling state to improve latency
*/
- if (cpu_data->utilized)
+ if (teo_cpu_is_utilized(dev->cpu, cpu_data))
idx = teo_find_shallower_state(drv, dev, idx, duration_ns, true);

end: