[PATCH v3 7/9] sched/fair: Dissociate wakeup decisions from SD flag value

From: Valentin Schneider
Date: Wed Apr 15 2020 - 17:06:49 EST


The CFS wakeup code will only ever go through EAS / its fast path on
"regular" wakeups (i.e. not on forks or execs). These are currently gated
by a check against 'sd_flag', which would be SD_BALANCE_WAKE at wakeup.

However, we now have a flag that explicitly tells us whether a wakeup is a
"regular" one, so hinge those conditions on that flag instead.

Signed-off-by: Valentin Schneider <valentin.schneider@xxxxxxx>
---
kernel/sched/fair.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index b0bf98e6798b..f20e5cd6515c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6642,7 +6642,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags)
sd_flag = SD_BALANCE_EXEC;
}

- if (sd_flag & SD_BALANCE_WAKE) {
+ if (wake_flags & WF_TTWU) {
record_wakee(p);

if (sched_energy_enabled()) {
@@ -6679,9 +6679,8 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags)
if (unlikely(sd)) {
/* Slow path */
new_cpu = find_idlest_cpu(sd, p, cpu, prev_cpu, sd_flag);
- } else if (sd_flag & SD_BALANCE_WAKE) { /* XXX always ? */
+ } else if (wake_flags & WF_TTWU) { /* XXX always ? */
/* Fast path */
-
new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);

if (want_affine)
--
2.24.0