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Diffstat (limited to 'drivers/cpuidle/cpuidle.c')
-rw-r--r--drivers/cpuidle/cpuidle.c25
1 files changed, 23 insertions, 2 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 83af15f77f66..ef2ea1b12cd8 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -368,6 +368,19 @@ void cpuidle_reflect(struct cpuidle_device *dev, int index)
cpuidle_curr_governor->reflect(dev, index);
}
+/*
+ * Min polling interval of 10usec is a guess. It is assuming that
+ * for most users, the time for a single ping-pong workload like
+ * perf bench pipe would generally complete within 10usec but
+ * this is hardware dependant. Actual time can be estimated with
+ *
+ * perf bench sched pipe -l 10000
+ *
+ * Run multiple times to avoid cpufreq effects.
+ */
+#define CPUIDLE_POLL_MIN 10000
+#define CPUIDLE_POLL_MAX (TICK_NSEC / 16)
+
/**
* cpuidle_poll_time - return amount of time to poll for,
* governors can override dev->poll_limit_ns if necessary
@@ -382,15 +395,23 @@ u64 cpuidle_poll_time(struct cpuidle_driver *drv,
int i;
u64 limit_ns;
+ BUILD_BUG_ON(CPUIDLE_POLL_MIN > CPUIDLE_POLL_MAX);
+
if (dev->poll_limit_ns)
return dev->poll_limit_ns;
- limit_ns = TICK_NSEC;
+ limit_ns = CPUIDLE_POLL_MAX;
for (i = 1; i < drv->state_count; i++) {
+ u64 state_limit;
+
if (dev->states_usage[i].disable)
continue;
- limit_ns = drv->states[i].target_residency_ns;
+ state_limit = drv->states[i].target_residency_ns;
+ if (state_limit < CPUIDLE_POLL_MIN)
+ continue;
+
+ limit_ns = min_t(u64, state_limit, CPUIDLE_POLL_MAX);
break;
}