* shallower than the one whose bin is fallen into by the sleep length (these
* situations are referred to as "intercepts" below).
*
- * In addition to the metrics described above, the governor counts recent
- * intercepts (that is, intercepts that have occurred during the last
- * %NR_RECENT invocations of it for the given CPU) for each bin.
- *
* In order to select an idle state for a CPU, the governor takes the following
* steps (modulo the possible latency constraint that must be taken into account
* too):
*
* 1. Find the deepest CPU idle state whose target residency does not exceed
- * the current sleep length (the candidate idle state) and compute 3 sums as
+ * the current sleep length (the candidate idle state) and compute 2 sums as
* follows:
*
* - The sum of the "hits" and "intercepts" metrics for the candidate state
* idle long enough to avoid being intercepted if the sleep length had been
* equal to the current one).
*
- * - The sum of the numbers of recent intercepts for all of the idle states
- * shallower than the candidate one.
- *
- * 2. If the second sum is greater than the first one or the third sum is
- * greater than %NR_RECENT / 2, the CPU is likely to wake up early, so look
- * for an alternative idle state to select.
+ * 2. If the second sum is greater than the first one the CPU is likely to wake
+ * up early, so look for an alternative idle state to select.
*
* - Traverse the idle states shallower than the candidate one in the
* descending order.
*
- * - For each of them compute the sum of the "intercepts" metrics and the sum
- * of the numbers of recent intercepts over all of the idle states between
- * it and the candidate one (including the former and excluding the
- * latter).
+ * - For each of them compute the sum of the "intercepts" metrics over all
+ * of the idle states between it and the candidate one (including the
+ * former and excluding the latter).
*
* - If each of these sums that needs to be taken into account (because the
* check related to it has indicated that the CPU is likely to wake up
#define PULSE 1024
#define DECAY_SHIFT 3
-/*
- * Number of the most recent idle duration values to take into consideration for
- * the detection of recent early wakeup patterns.
- */
-#define NR_RECENT 9
-
/**
* struct teo_bin - Metrics used by the TEO cpuidle governor.
* @intercepts: The "intercepts" metric.
* @hits: The "hits" metric.
- * @recent: The number of recent "intercepts".
*/
struct teo_bin {
unsigned int intercepts;
unsigned int hits;
- unsigned int recent;
};
/**
* @sleep_length_ns: Time till the closest timer event (at the selection time).
* @state_bins: Idle state data bins for this CPU.
* @total: Grand total of the "intercepts" and "hits" metrics for all bins.
- * @next_recent_idx: Index of the next @recent_idx entry to update.
- * @recent_idx: Indices of bins corresponding to recent "intercepts".
* @tick_hits: Number of "hits" after TICK_NSEC.
*/
struct teo_cpu {
s64 sleep_length_ns;
struct teo_bin state_bins[CPUIDLE_STATE_MAX];
unsigned int total;
- int next_recent_idx;
- int recent_idx[NR_RECENT];
unsigned int tick_hits;
};
}
}
- i = cpu_data->next_recent_idx++;
- if (cpu_data->next_recent_idx >= NR_RECENT)
- cpu_data->next_recent_idx = 0;
-
- if (cpu_data->recent_idx[i] >= 0)
- cpu_data->state_bins[cpu_data->recent_idx[i]].recent--;
-
/*
* If the deepest state's target residency is below the tick length,
* make a record of it to help teo_select() decide whether or not
* Otherwise, update the "intercepts" metric for the bin fallen into by
* the measured idle duration.
*/
- if (idx_timer == idx_duration) {
+ if (idx_timer == idx_duration)
cpu_data->state_bins[idx_timer].hits += PULSE;
- cpu_data->recent_idx[i] = -1;
- } else {
+ else
cpu_data->state_bins[idx_duration].intercepts += PULSE;
- cpu_data->state_bins[idx_duration].recent++;
- cpu_data->recent_idx[i] = idx_duration;
- }
end:
cpu_data->total += PULSE;
unsigned int tick_intercept_sum = 0;
unsigned int idx_intercept_sum = 0;
unsigned int intercept_sum = 0;
- unsigned int idx_recent_sum = 0;
- unsigned int recent_sum = 0;
unsigned int idx_hit_sum = 0;
unsigned int hit_sum = 0;
int constraint_idx = 0;
int idx0 = 0, idx = -1;
- bool alt_intercepts, alt_recent;
s64 duration_ns;
int i;
*/
intercept_sum += prev_bin->intercepts;
hit_sum += prev_bin->hits;
- recent_sum += prev_bin->recent;
if (dev->states_usage[i].disable)
continue;
/* Save the sums for the current state. */
idx_intercept_sum = intercept_sum;
idx_hit_sum = hit_sum;
- idx_recent_sum = recent_sum;
}
/* Avoid unnecessary overhead. */
* If the sum of the intercepts metric for all of the idle states
* shallower than the current candidate one (idx) is greater than the
* sum of the intercepts and hits metrics for the candidate state and
- * all of the deeper states, or the sum of the numbers of recent
- * intercepts over all of the states shallower than the candidate one
- * is greater than a half of the number of recent events taken into
- * account, a shallower idle state is likely to be a better choice.
+ * all of the deeper states a shallower idle state is likely to be a
+ * better choice.
*/
- alt_intercepts = 2 * idx_intercept_sum > cpu_data->total - idx_hit_sum;
- alt_recent = idx_recent_sum > NR_RECENT / 2;
- if (alt_recent || alt_intercepts) {
+ if (2 * idx_intercept_sum > cpu_data->total - idx_hit_sum) {
int first_suitable_idx = idx;
/*
* Look for the deepest idle state whose target residency had
* not exceeded the idle duration in over a half of the relevant
- * cases (both with respect to intercepts overall and with
- * respect to the recent intercepts only) in the past.
+ * cases in the past.
*
* Take the possible duration limitation present if the tick
* has been stopped already into account.
*/
intercept_sum = 0;
- recent_sum = 0;
for (i = idx - 1; i >= 0; i--) {
struct teo_bin *bin = &cpu_data->state_bins[i];
intercept_sum += bin->intercepts;
- recent_sum += bin->recent;
- if ((!alt_recent || 2 * recent_sum > idx_recent_sum) &&
- (!alt_intercepts ||
- 2 * intercept_sum > idx_intercept_sum)) {
+ if (2 * intercept_sum > idx_intercept_sum) {
/*
* Use the current state unless it is too
* shallow or disabled, in which case take the
struct cpuidle_device *dev)
{
struct teo_cpu *cpu_data = per_cpu_ptr(&teo_cpus, dev->cpu);
- int i;
memset(cpu_data, 0, sizeof(*cpu_data));
- for (i = 0; i < NR_RECENT; i++)
- cpu_data->recent_idx[i] = -1;
-
return 0;
}
projects / users / dwmw2 / linux.git / commitdiff