[RFC PATCH v2 6/8] cpuidle: make fast idle threshold tunable

Aubrey Li
2017-09-30T07:21:48Z

Add a knob to make fast idle threshold tunable

Signed-off-by: Aubrey Li <aubrey.li@linux.intel.com>
---
drivers/cpuidle/cpuidle.c | 3 ++-
include/linux/cpuidle.h | 1 +
kernel/sysctl.c | 12 ++++++++++++
3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 6cb7e17..5d4f0b6 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -35,6 +35,7 @@ LIST_HEAD(cpuidle_detected_devices);
static int enabled_devices;
static int off __read_mostly;
static int initialized __read_mostly;
+int sysctl_fast_idle_ratio = 10;

int cpuidle_disabled(void)
{
@@ -346,7 +347,7 @@ void cpuidle_predict(void)
if (!dev)
return;

- overhead_threshold = dev->idle_stat.overhead;
+ overhead_threshold = dev->idle_stat.overhead * sysctl_fast_idle_ratio;

if (cpuidle_curr_governor->predict) {
dev->idle_stat.predicted_us = cpuidle_curr_governor->predict();
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 791db15..45b8264 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -24,6 +24,7 @@ struct module;
struct cpuidle_device;
struct cpuidle_driver;

+extern int sysctl_fast_idle_ratio;

/****************************
* CPUIDLE DEVICE INTERFACE *
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 6648fbb..97f7e8af 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -67,6 +67,7 @@
#include <linux/kexec.h>
#include <linux/bpf.h>
#include <linux/mount.h>
+#include <linux/cpuidle.h>

#include <linux/uaccess.h>
#include <asm/processor.h>
@@ -1229,6 +1230,17 @@ static struct ctl_table kern_table[] = {
.extra2 = &one,
},
#endif
+#ifdef CONFIG_CPU_IDLE
+ {
+ .procname = "fast_idle_ratio",
+ .data = &sysctl_fast_idle_ratio,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &one,
+ .extra2 = &one_hundred,
+ },
+#endif
{ }
};

--
2.7.4