[PATCH RFC] cpuidle/drivers/menu: Remove get_loadavg in the performance multiplier

From: Daniel Lezcano
Date: Tue Sep 25 2018 - 05:39:09 EST


The function get_loadavg() returns almost always zero. To be more
precise, statistically speaking for a total of 1023379 times passing
to the function, the load is equal to zero 1020728 times, greater than
100, 610 times, the remaining is between 0 and 5.

I'm putting in question this metric. Is it worth to keep it?

Cc: Todd Kjos <tkjos@xxxxxxxxxx>
Cc: Joel Fernandes <joelaf@xxxxxxxxxx>
Cc: Colin Cross <ccross@xxxxxxxxxxx>
Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
---
drivers/cpuidle/governors/menu.c | 15 ++++-----------
1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index e26a409..d939b8e 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -173,18 +173,10 @@ static inline int which_bucket(unsigned int duration, unsigned long nr_iowaiters
* to be, the higher this multiplier, and thus the higher
* the barrier to go to an expensive C state.
*/
-static inline int performance_multiplier(unsigned long nr_iowaiters, unsigned long load)
+static inline int performance_multiplier(unsigned long nr_iowaiters)
{
- int mult = 1;
-
- /* for higher loadavg, we are more reluctant */
-
- mult += 2 * get_loadavg(load);
-
/* for IO wait tasks (per cpu!) we add 5x each */
- mult += 10 * nr_iowaiters;
-
- return mult;
+ return 1 + 10 * nr_iowaiters;
}

static DEFINE_PER_CPU(struct menu_device, menu_devices);
@@ -359,7 +351,8 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
* Use the performance multiplier and the user-configurable
* latency_req to determine the maximum exit latency.
*/
- interactivity_req = data->predicted_us / performance_multiplier(nr_iowaiters, cpu_load);
+ interactivity_req = data->predicted_us /
+ performance_multiplier(nr_iowaiters);
if (latency_req > interactivity_req)
latency_req = interactivity_req;
}
--
2.7.4