diff options
| author | Tejun Heo <tj@kernel.org> | 2026-08-15 13:08:28 -1000 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2026-08-15 16:07:49 -1000 |
| commit | 0ec5dd0669291c8ffbee096367e078c26cbcc332 (patch) | |
| tree | e8cbaee8bb1d59ff94872385e7d48641961c5037 /include/linux/sched | |
| parent | f7b6d128dd49a6eec09066ecfd29095f12588786 (diff) | |
sched_ext: Use runnable_at for the default core-sched task ordering
The default core-sched ordering runs the longest waiting task first by
comparing p->scx.core_sched_at stamps. The stamp is maintained under two
rules. touch_core_sched() stamps when a task starts waiting for a CPU and
when its slice runs out. If the scheduler implements
ops.core_sched_before(), touch_core_sched_dispatch() re-stamps on every
dispatch.
A comparison can see one stamp taken under each rule, which isn't a
meaningful ordering. The dispatch rule also buys little - it only aligns
bypass-mode comparisons with the local DSQ order. Multiple schedulers make
the mixed comparisons more common.
Wait time is what p->scx.runnable_at already tracks for the stall watchdog.
Delete core_sched_at with both touch functions and compare runnable_at in
the scx_prio_less() fallback.
runnable_at is refreshed only on enqueue and goes stale while a task keeps
occupying its CPU. Instead of re-stamping, order a running task after every
waiting task as it is the most recently serviced.
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'include/linux/sched')
| -rw-r--r-- | include/linux/sched/ext.h | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/include/linux/sched/ext.h b/include/linux/sched/ext.h index a3ec980e2925..582d7cd4a983 100644 --- a/include/linux/sched/ext.h +++ b/include/linux/sched/ext.h @@ -212,9 +212,6 @@ struct sched_ext_entity { struct list_head runnable_node; /* rq->scx.runnable_list */ unsigned long runnable_at; -#ifdef CONFIG_SCHED_CORE - u64 core_sched_at; /* see scx_prio_less() */ -#endif #ifdef CONFIG_EXT_SUB_SCHED unsigned long rescue_at; /* queued on a rescue DSQ at, jiffies */ #endif |