}
/*
- * compute_energy(): Estimates the energy that would be consumed if @p was
+ * compute_energy(): Estimates the energy that @pd would consume if @p was
* migrated to @dst_cpu. compute_energy() predicts what will be the utilization
- * landscape of the * CPUs after the task migration, and uses the Energy Model
+ * landscape of @pd's CPUs after the task migration, and uses the Energy Model
* to compute what would be the energy if we decided to actually migrate that
* task.
*/
static long
compute_energy(struct task_struct *p, int dst_cpu, struct perf_domain *pd)
{
- unsigned int max_util, util_cfs, cpu_util, cpu_cap;
- unsigned long sum_util, energy = 0;
- struct task_struct *tsk;
+ struct cpumask *pd_mask = perf_domain_span(pd);
+ unsigned long cpu_cap = arch_scale_cpu_capacity(cpumask_first(pd_mask));
+ unsigned long max_util = 0, sum_util = 0;
int cpu;
- for (; pd; pd = pd->next) {
- struct cpumask *pd_mask = perf_domain_span(pd);
+ /*
+ * The capacity state of CPUs of the current rd can be driven by CPUs
+ * of another rd if they belong to the same pd. So, account for the
+ * utilization of these CPUs too by masking pd with cpu_online_mask
+ * instead of the rd span.
+ *
+ * If an entire pd is outside of the current rd, it will not appear in
+ * its pd list and will not be accounted by compute_energy().
+ */
+ for_each_cpu_and(cpu, pd_mask, cpu_online_mask) {
+ unsigned long cpu_util, util_cfs = cpu_util_next(cpu, p, dst_cpu);
+ struct task_struct *tsk = cpu == dst_cpu ? p : NULL;
/*
- * The energy model mandates all the CPUs of a performance
- * domain have the same capacity.
+ * Busy time computation: utilization clamping is not
+ * required since the ratio (sum_util / cpu_capacity)
+ * is already enough to scale the EM reported power
+ * consumption at the (eventually clamped) cpu_capacity.
*/
- cpu_cap = arch_scale_cpu_capacity(cpumask_first(pd_mask));
- max_util = sum_util = 0;
+ sum_util += schedutil_cpu_util(cpu, util_cfs, cpu_cap,
+ ENERGY_UTIL, NULL);
/*
- * The capacity state of CPUs of the current rd can be driven by
- * CPUs of another rd if they belong to the same performance
- * domain. So, account for the utilization of these CPUs too
- * by masking pd with cpu_online_mask instead of the rd span.
- *
- * If an entire performance domain is outside of the current rd,
- * it will not appear in its pd list and will not be accounted
- * by compute_energy().
+ * Performance domain frequency: utilization clamping
+ * must be considered since it affects the selection
+ * of the performance domain frequency.
+ * NOTE: in case RT tasks are running, by default the
+ * FREQUENCY_UTIL's utilization can be max OPP.
*/
- for_each_cpu_and(cpu, pd_mask, cpu_online_mask) {
- util_cfs = cpu_util_next(cpu, p, dst_cpu);
-
- /*
- * Busy time computation: utilization clamping is not
- * required since the ratio (sum_util / cpu_capacity)
- * is already enough to scale the EM reported power
- * consumption at the (eventually clamped) cpu_capacity.
- */
- sum_util += schedutil_cpu_util(cpu, util_cfs, cpu_cap,
- ENERGY_UTIL, NULL);
-
- /*
- * Performance domain frequency: utilization clamping
- * must be considered since it affects the selection
- * of the performance domain frequency.
- * NOTE: in case RT tasks are running, by default the
- * FREQUENCY_UTIL's utilization can be max OPP.
- */
- tsk = cpu == dst_cpu ? p : NULL;
- cpu_util = schedutil_cpu_util(cpu, util_cfs, cpu_cap,
- FREQUENCY_UTIL, tsk);
- max_util = max(max_util, cpu_util);
- }
-
- energy += em_pd_energy(pd->em_pd, max_util, sum_util);
+ cpu_util = schedutil_cpu_util(cpu, util_cfs, cpu_cap,
+ FREQUENCY_UTIL, tsk);
+ max_util = max(max_util, cpu_util);
}
- return energy;
+ return em_pd_energy(pd->em_pd, max_util, sum_util);
}
/*
* other use-cases too. So, until someone finds a better way to solve this,
* let's keep things simple by re-using the existing slow path.
*/
-
static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
{
- unsigned long prev_energy = ULONG_MAX, best_energy = ULONG_MAX;
+ unsigned long prev_delta = ULONG_MAX, best_delta = ULONG_MAX;
struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
+ unsigned long cpu_cap, util, base_energy = 0;
int cpu, best_energy_cpu = prev_cpu;
- struct perf_domain *head, *pd;
- unsigned long cpu_cap, util;
struct sched_domain *sd;
+ struct perf_domain *pd;
rcu_read_lock();
pd = rcu_dereference(rd->pd);
if (!pd || READ_ONCE(rd->overutilized))
goto fail;
- head = pd;
/*
* Energy-aware wake-up happens on the lowest sched_domain starting
goto unlock;
for (; pd; pd = pd->next) {
- unsigned long cur_energy, spare_cap, max_spare_cap = 0;
+ unsigned long cur_delta, spare_cap, max_spare_cap = 0;
+ unsigned long base_energy_pd;
int max_spare_cap_cpu = -1;
+ /* Compute the 'base' energy of the pd, without @p */
+ base_energy_pd = compute_energy(p, -1, pd);
+ base_energy += base_energy_pd;
+
for_each_cpu_and(cpu, perf_domain_span(pd), sched_domain_span(sd)) {
if (!cpumask_test_cpu(cpu, p->cpus_ptr))
continue;
/* Always use prev_cpu as a candidate. */
if (cpu == prev_cpu) {
- prev_energy = compute_energy(p, prev_cpu, head);
- best_energy = min(best_energy, prev_energy);
- continue;
+ prev_delta = compute_energy(p, prev_cpu, pd);
+ prev_delta -= base_energy_pd;
+ best_delta = min(best_delta, prev_delta);
}
/*
/* Evaluate the energy impact of using this CPU. */
if (max_spare_cap_cpu >= 0) {
- cur_energy = compute_energy(p, max_spare_cap_cpu, head);
- if (cur_energy < best_energy) {
- best_energy = cur_energy;
+ cur_delta = compute_energy(p, max_spare_cap_cpu, pd);
+ cur_delta -= base_energy_pd;
+ if (cur_delta < best_delta) {
+ best_delta = cur_delta;
best_energy_cpu = max_spare_cap_cpu;
}
}
* Pick the best CPU if prev_cpu cannot be used, or if it saves at
* least 6% of the energy used by prev_cpu.
*/
- if (prev_energy == ULONG_MAX)
+ if (prev_delta == ULONG_MAX)
return best_energy_cpu;
- if ((prev_energy - best_energy) > (prev_energy >> 4))
+ if ((prev_delta - best_delta) > ((prev_delta + base_energy) >> 4))
return best_energy_cpu;
return prev_cpu;
projects / users / jedix / linux-maple.git / commitdiff