The new scheme is clearly better (XXX need !hackbench numbers), clean
up the mess.
This leaves everything under SIS_PROP, which I think Facebook still
uses (to disable), Rik?
Cc: Rik van Riel <r...@surriel.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
kernel/sched/fair.c | 43 ++++++++++++++++++-------------------------
kernel/sched/features.h | 3 ---
2 files changed, 18 insertions(+), 28 deletions(-)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6432,16 +6432,18 @@ static int select_idle_cpu(struct task_s
int cpu, loops = 0, nr = INT_MAX;
struct sched_domain *this_sd;
u64 avg_cost, avg_idle;
- u64 time, cost;
- s64 delta;
+ struct rq *this_rq;
+ u64 time;
this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc));
if (!this_sd)
return -1;
- if (sched_feat(SIS_AGE)) {
+ if (sched_feat(SIS_PROP)) {
unsigned long now = jiffies;
- struct rq *this_rq = this_rq();
+ u64 span_avg;
+
+ this_rq = this_rq();
/*
* If we're busy, the assumption that the last idle period
@@ -6456,24 +6458,16 @@ static int select_idle_cpu(struct task_s
}
avg_idle = this_rq->wake_avg;
- } else {
- /*
- * Due to large variance we need a large fuzz factor; hackbench
- * in particularly is sensitive here.
- */
- avg_idle = this_rq()->avg_idle / 512;
- }
- avg_cost = this_sd->avg_scan_cost + 1;
+ avg_cost = this_sd->avg_scan_cost + 1;
- if (sched_feat(SIS_PROP)) {
- u64 span_avg = sd->span_weight * avg_idle;
+ span_avg = sd->span_weight * avg_idle;
if (span_avg > sis_min_cores * avg_cost)
nr = div_u64(span_avg, avg_cost);
else
nr = sis_min_cores;
- }
- time = local_clock();
+ time = local_clock();
+ }
#ifdef CONFIG_SCHED_SMT
if (sched_feat(SIS_FOLD) && static_branch_likely(&sched_smt_present) &&
@@ -6483,26 +6477,25 @@ static int select_idle_cpu(struct task_s
#endif
cpu = __select_idle_cpu(p, sd, target, nr * sched_smt_weight, &loops);
- time = local_clock() - time;
+ if (sched_feat(SIS_PROP)) {
+ s64 delta;
- if (sched_feat(SIS_ONCE)) {
- struct rq *this_rq = this_rq();
+ time = local_clock() - time;
/*
* We need to consider the cost of all wakeups between
* consequtive idle periods. We can only use the predicted
* idle time once.
*/
- if (this_rq->wake_avg > time)
+ if (avg_idle > time)
this_rq->wake_avg -= time;
else
this_rq->wake_avg = 0;
- }
- time = div_u64(time, loops);
- cost = this_sd->avg_scan_cost;
- delta = (s64)(time - cost) / 8;
- this_sd->avg_scan_cost += delta;
+ time = div_u64(time, loops);
+ delta = (s64)(time - avg_cost) / 8;
+ this_sd->avg_scan_cost += delta;
+ }
return cpu;
}
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -56,9 +56,6 @@ SCHED_FEAT(TTWU_QUEUE, true)
* When doing wakeups, attempt to limit superfluous scans of the LLC domain.
*/
SCHED_FEAT(SIS_PROP, true)
-
-SCHED_FEAT(SIS_AGE, true)
-SCHED_FEAT(SIS_ONCE, true)
SCHED_FEAT(SIS_FOLD, true)
/*
