linux-kernel - [PATCH] cpuidle: teo: Get rid of redundant check in teo

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Date:   Tue, 30 Jul 2019 12:11:08 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux PM <linux-pm@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] cpuidle: teo: Get rid of redundant check in teo_update()

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Notice that setting measured_us to UINT_MAX in teo_update() earlier
doesn't change the behavior of the following code, so do that and
eliminate a redundant check used for setting measured_us to UINT_MAX.

This change is not expected to alter functionality.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/cpuidle/governors/teo.c |   16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

Index: linux-pm/drivers/cpuidle/governors/teo.c
===================================================================
--- linux-pm.orig/drivers/cpuidle/governors/teo.c
+++ linux-pm/drivers/cpuidle/governors/teo.c
@@ -125,10 +125,11 @@ static void teo_update(struct cpuidle_dr
 
 	if (cpu_data->time_span_ns >= cpu_data->sleep_length_ns) {
 		/*
-		 * One of the safety nets has triggered or this was a timer
-		 * wakeup (or equivalent).
+		 * One of the safety nets has triggered or the wakeup was close
+		 * enough to the closest timer event expected at the idle state
+		 * selection time to be discarded.
 		 */
-		measured_us = sleep_length_us;
+		measured_us = UINT_MAX;
 	} else {
 		unsigned int lat = drv->states[cpu_data->last_state].exit_latency;
 
@@ -189,15 +190,6 @@ static void teo_update(struct cpuidle_dr
 	}
 
 	/*
-	 * If the total time span between idle state selection and the "reflect"
-	 * callback is greater than or equal to the sleep length determined at
-	 * the idle state selection time, the wakeup is likely to be due to a
-	 * timer event.
-	 */
-	if (cpu_data->time_span_ns >= cpu_data->sleep_length_ns)
-		measured_us = UINT_MAX;
-
-	/*
 	 * Save idle duration values corresponding to non-timer wakeups for
 	 * pattern detection.
 	 */