cpuidle: menu: Take negative "sleep length" values into account

Make the menu governor check the tick_nohz_get_next_hrtimer()
return value so as to avoid dealing with negative "sleep length"
values and make it use that value directly when the tick is stopped.

While at it, rename local variable delta_next in menu_select() to
delta_tick which better reflects its purpose.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index b0a7ad5..c3aa8d6 100644 (file)
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -271,7 +271,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
        u64 predicted_ns;
        u64 interactivity_req;
        unsigned long nr_iowaiters;
-       ktime_t delta_next;
+       ktime_t delta, delta_tick;
        int i, idx;
 
        if (data->needs_update) {
@@ -280,7 +280,12 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
        }
 
        /* determine the expected residency time, round up */
-       data->next_timer_ns = tick_nohz_get_sleep_length(&delta_next);
+       delta = tick_nohz_get_sleep_length(&delta_tick);
+       if (unlikely(delta < 0)) {
+               delta = 0;
+               delta_tick = 0;
+       }
+       data->next_timer_ns = delta;
 
        nr_iowaiters = nr_iowait_cpu(dev->cpu);
        data->bucket = which_bucket(data->next_timer_ns, nr_iowaiters);
@@ -318,7 +323,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
                 * state selection.
                 */
                if (predicted_ns < TICK_NSEC)
-                       predicted_ns = delta_next;
+                       predicted_ns = data->next_timer_ns;
        } else {
                /*
                 * Use the performance multiplier and the user-configurable
@@ -377,7 +382,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
                         * stuck in the shallow one for too long.
                         */
                        if (drv->states[idx].target_residency_ns < TICK_NSEC &&
-                           s->target_residency_ns <= delta_next)
+                           s->target_residency_ns <= delta_tick)
                                idx = i;
 
                        return idx;
@@ -399,7 +404,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
             predicted_ns < TICK_NSEC) && !tick_nohz_tick_stopped()) {
                *stop_tick = false;
 
-               if (idx > 0 && drv->states[idx].target_residency_ns > delta_next) {
+               if (idx > 0 && drv->states[idx].target_residency_ns > delta_tick) {
                        /*
                         * The tick is not going to be stopped and the target
                         * residency of the state to be returned is not within
@@ -411,7 +416,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
                                        continue;
 
                                idx = i;
-                               if (drv->states[i].target_residency_ns <= delta_next)
+                               if (drv->states[i].target_residency_ns <= delta_tick)
                                        break;
                        }
                }