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Message-ID: <4991828.GXAFRqVoOG@rjwysocki.net>
Date: Thu, 03 Apr 2025 21:16:47 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Christian Loehle <christian.loehle@....com>,
Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>,
Doug Smythies <dsmythies@...us.net>,
Aboorva Devarajan <aboorvad@...ux.ibm.com>
Subject:
[PATCH v1 1/2] cpuidle: teo: Move candidate state lookup to separate function
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Move the code looking up a new candidate idle state in teo, after
deciding that the initial candidate (the deepest enabled idle state) is
likely too deep, into a separate function in preparation for subsequent
changes.
No intentional functional impact.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
drivers/cpuidle/governors/teo.c | 120 +++++++++++++++++++++-------------------
1 file changed, 63 insertions(+), 57 deletions(-)
--- a/drivers/cpuidle/governors/teo.c
+++ b/drivers/cpuidle/governors/teo.c
@@ -259,6 +259,67 @@
return state_idx;
}
+static int teo_get_candidate(struct cpuidle_driver *drv,
+ struct cpuidle_device *dev,
+ struct teo_cpu *cpu_data,
+ int idx, unsigned int idx_intercepts)
+{
+ int first_suitable_idx = idx;
+ unsigned int intercepts = 0;
+ int i;
+
+ /*
+ * Look for the deepest idle state whose target residency had
+ * not exceeded the idle duration in over a half of the relevant
+ * cases in the past.
+ *
+ * Take the possible duration limitation present if the tick
+ * has been stopped already into account.
+ */
+ for (i = idx - 1; i >= 0; i--) {
+ intercepts += cpu_data->state_bins[i].intercepts;
+ if (2 * intercepts > idx_intercepts) {
+ /*
+ * Use the current state unless it is too
+ * shallow or disabled, in which case take the
+ * first enabled state that is deep enough.
+ */
+ if (teo_state_ok(i, drv) && !dev->states_usage[i].disable) {
+ idx = i;
+ break;
+ }
+
+ idx = first_suitable_idx;
+ break;
+ }
+
+ if (dev->states_usage[i].disable)
+ continue;
+
+ if (teo_state_ok(i, drv)) {
+ /*
+ * The current state is deep enough, but still
+ * there may be a better one.
+ */
+ first_suitable_idx = i;
+ continue;
+ }
+
+ /*
+ * The current state is too shallow, so if no suitable
+ * states other than the initial candidate have been
+ * found, give up (the remaining states to check are
+ * shallower still), but otherwise the first suitable
+ * state other than the initial candidate may turn out
+ * to be preferable.
+ */
+ if (first_suitable_idx == idx)
+ break;
+ }
+
+ return idx;
+}
+
/**
* teo_select - Selects the next idle state to enter.
* @drv: cpuidle driver containing state data.
@@ -355,63 +416,8 @@
* all of the deeper states, a shallower idle state is likely to be a
* better choice.
*/
- if (2 * idx_intercept_sum > cpu_data->total - idx_hit_sum) {
- int first_suitable_idx = idx;
-
- /*
- * Look for the deepest idle state whose target residency had
- * not exceeded the idle duration in over a half of the relevant
- * cases in the past.
- *
- * Take the possible duration limitation present if the tick
- * has been stopped already into account.
- */
- intercept_sum = 0;
-
- for (i = idx - 1; i >= 0; i--) {
- struct teo_bin *bin = &cpu_data->state_bins[i];
-
- intercept_sum += bin->intercepts;
-
- if (2 * intercept_sum > idx_intercept_sum) {
- /*
- * Use the current state unless it is too
- * shallow or disabled, in which case take the
- * first enabled state that is deep enough.
- */
- if (teo_state_ok(i, drv) &&
- !dev->states_usage[i].disable) {
- idx = i;
- break;
- }
- idx = first_suitable_idx;
- break;
- }
-
- if (dev->states_usage[i].disable)
- continue;
-
- if (teo_state_ok(i, drv)) {
- /*
- * The current state is deep enough, but still
- * there may be a better one.
- */
- first_suitable_idx = i;
- continue;
- }
-
- /*
- * The current state is too shallow, so if no suitable
- * states other than the initial candidate have been
- * found, give up (the remaining states to check are
- * shallower still), but otherwise the first suitable
- * state other than the initial candidate may turn out
- * to be preferable.
- */
- if (first_suitable_idx == idx)
- break;
- }
- }
+ if (2 * idx_intercept_sum > cpu_data->total - idx_hit_sum)
+ idx = teo_get_candidate(drv, dev, cpu_data, idx, idx_intercept_sum);
/*
* If there is a latency constraint, it may be necessary to select an
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