From: Xuewen Yan <xuewen....@unisoc.com>
now the energy delta compute as follow:
base_energy_pd = compute_energy(p, -1, pd);
--->Traverse all CPUs in pd
--->em_pd_energy()
----------------------------------------------------- \
search for the max_sapre_cap_cpu \
--------------------------------- search time
cur_delta = compute_energy(p, max_spare_cap_cpu, pd); /
--->Traverse all CPUs in pd /
---------------------------------------------------- /
--->em_pd_energy()
cur_delta -= base_energy_pd;
During the search_time, or when calculate the cpu_util in
compute_energy(), there may occurred task dequeue or cpu_util change,
it may cause the cur_energy < base_energy_pd, so the cur_delta
would be negative. But the cur_delta is unsigned long, at this time,
the cur_delta would always bigger than best_delta of last pd.
Change the vars to signed long.
Signed-off-by: Xuewen Yan <xuewen....@unisoc.com>
---
kernel/sched/fair.c | 31 +++++++++++++++++--------------
1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 794c2cb945f8..310d9d215cd7 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6586,7 +6586,7 @@ compute_energy(struct task_struct *p, int dst_cpu, struct
perf_domain *pd)
*/
static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
{
- unsigned long prev_delta = ULONG_MAX, best_delta = ULONG_MAX;
+ long prev_delta = LONG_MAX, best_delta = LONG_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;
@@ -6613,13 +6613,11 @@ static int find_energy_efficient_cpu(struct task_struct
*p, int prev_cpu)
goto unlock;
for (; pd; pd = pd->next) {
- unsigned long cur_delta, spare_cap, max_spare_cap = 0;
+ long cur_delta;
+ unsigned long 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;
+ bool prev_in_pd = false;
for_each_cpu_and(cpu, perf_domain_span(pd),
sched_domain_span(sd)) {
if (!cpumask_test_cpu(cpu, p->cpus_ptr))
@@ -6641,13 +6639,8 @@ static int find_energy_efficient_cpu(struct task_struct
*p, int prev_cpu)
if (!fits_capacity(util, cpu_cap))
continue;
- /* Always use prev_cpu as a candidate. */
- if (cpu == prev_cpu) {
- prev_delta = compute_energy(p, prev_cpu, pd);
- prev_delta -= base_energy_pd;
- best_delta = min(best_delta, prev_delta);
- }
-
+ if (cpu == prev_cpu)
+ prev_in_pd = true;
/*
* Find the CPU with the maximum spare capacity in
* the performance domain
@@ -6658,6 +6651,16 @@ static int find_energy_efficient_cpu(struct task_struct
*p, int prev_cpu)
}
}
+ /* Compute the 'base' energy of the pd, without @p */
+ base_energy_pd = compute_energy(p, -1, pd);
+ base_energy += base_energy_pd;
+
+ /* Always use prev_cpu as a candidate. */
+ if (prev_in_pd) {
+ 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 && max_spare_cap_cpu != prev_cpu) {
cur_delta = compute_energy(p, max_spare_cap_cpu, pd);
@@ -6675,7 +6678,7 @@ static int find_energy_efficient_cpu(struct task_struct
*p, int prev_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_delta == ULONG_MAX)
+ if (prev_delta == LONG_MAX)
return best_energy_cpu;
if ((prev_delta - best_delta) > ((prev_delta + base_energy) >> 4))
--
2.29.0
