Change the C-state early break out algorithm in menu governor.
We only look at early breakouts that result in wakeups shorter than idle state's
target_residency. If such a breakout is frequent enough, eliminate the
particular idle state upto a timeout period.
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Index: linux-2.6.22-rc-mm/drivers/cpuidle/governors/menu.c
===================================================================
--- linux-2.6.22-rc-mm.orig/drivers/cpuidle/governors/menu.c 2007-06-05 09:39:27.000000000 -0700
+++ linux-2.6.22-rc-mm/drivers/cpuidle/governors/menu.c 2007-06-05 15:46:34.000000000 -0700
@@ -14,19 +14,20 @@
#include <linux/hrtimer.h>
#include <linux/tick.h>
-#define BM_HOLDOFF 20000 /* 20 ms */
+#define BM_HOLDOFF 20000 /* 20 ms */
+#define DEMOTION_THRESHOLD 5
+#define DEMOTION_TIMEOUT_MULTIPLIER 1000
struct menu_device {
int last_state_idx;
- int deepest_bm_state;
- int break_last_us;
- int break_elapsed_us;
+ int deepest_break_state;
+ struct timespec break_expire_time_ts;
+ int break_last_cnt;
+ int deepest_bm_state;
int bm_elapsed_us;
int bm_holdoff_us;
-
- unsigned long idle_jiffies;
};
static DEFINE_PER_CPU(struct menu_device, menu_devices);
@@ -45,7 +46,6 @@
/* determine the expected residency time */
expected_us = (s32) ktime_to_ns(tick_nohz_get_sleep_length()) / 1000;
- expected_us = min(expected_us, data->break_last_us);
/* determine the maximum state compatible with current BM status */
if (cpuidle_get_bm_activity())
@@ -53,17 +53,33 @@
if (data->bm_elapsed_us <= data->bm_holdoff_us)
max_state = data->deepest_bm_state + 1;
+ /* determine the maximum state compatible with recent idle breaks */
+ if (data->deepest_break_state >= 0) {
+ struct timespec now;
+ ktime_get_ts(&now);
+ if (timespec_compare(&data->break_expire_time_ts, &now) > 0) {
+ max_state = min(max_state,
+ data->deepest_break_state + 1);
+ } else {
+ data->deepest_break_state = -1;
+ }
+ }
+
/* find the deepest idle state that satisfies our constraints */
for (i = 1; i < max_state; i++) {
struct cpuidle_state *s = &dev->states[i];
+
if (s->target_residency > expected_us)
break;
+
if (s->exit_latency > system_latency_constraint())
break;
}
+ if (data->last_state_idx != i - 1)
+ data->break_last_cnt = 0;
+
data->last_state_idx = i - 1;
- data->idle_jiffies = tick_nohz_get_idle_jiffies();
return i - 1;
}
@@ -91,14 +107,27 @@
measured_us = USEC_PER_SEC / HZ;
data->bm_elapsed_us += measured_us;
- data->break_elapsed_us += measured_us;
+
+ if (data->last_state_idx == 0)
+ return;
/*
- * Did something other than the timer interrupt cause the break event?
+ * Did something other than the timer interrupt
+ * cause an early break event?
*/
- if (tick_nohz_get_idle_jiffies() == data->idle_jiffies) {
- data->break_last_us = data->break_elapsed_us;
- data->break_elapsed_us = 0;
+ if (unlikely(measured_us < target->target_residency)) {
+ if (data->break_last_cnt > DEMOTION_THRESHOLD) {
+ data->deepest_break_state = data->last_state_idx - 1;
+ ktime_get_ts(&data->break_expire_time_ts);
+ timespec_add_ns(&data->break_expire_time_ts,
+ target->target_residency *
+ DEMOTION_TIMEOUT_MULTIPLIER);
+ } else {
+ data->break_last_cnt++;
+ }
+ } else {
+ if (data->break_last_cnt > 0)
+ data->break_last_cnt--;
}
}
@@ -112,10 +141,9 @@
int i;
data->last_state_idx = 0;
- data->break_last_us = 0;
- data->break_elapsed_us = 0;
data->bm_elapsed_us = 0;
data->bm_holdoff_us = BM_HOLDOFF;
+ data->deepest_break_state = -1;
for (i = 1; i < dev->state_count; i++)
if (dev->states[i].flags & CPUIDLE_FLAG_CHECK_BM)
-
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