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| author | Tejun Heo <tj@kernel.org> | 2024-09-28 01:46:12 +0200 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2024-10-07 22:16:18 +0200 |
| commit | f207dc2dcdcf0e1e7d260b392784855ce8d84147 (patch) | |
| tree | c1133ab002eefb3c22fbacdd914dd899859a8319 /kernel/sched | |
| parent | sched/core: Make select_task_rq() take the pointer to wake_flags instead of v... (diff) | |
| download | linux-f207dc2dcdcf0e1e7d260b392784855ce8d84147.tar.xz linux-f207dc2dcdcf0e1e7d260b392784855ce8d84147.zip | |
sched/core: Add ENQUEUE_RQ_SELECTED to indicate whether ->select_task_rq() was called
During ttwu, ->select_task_rq() can be skipped if only one CPU is allowed or
migration is disabled. sched_ext schedulers may perform operations such as
direct dispatch from ->select_task_rq() path and it is useful for them to
know whether ->select_task_rq() was skipped in the ->enqueue_task() path.
Currently, sched_ext schedulers are using ENQUEUE_WAKEUP for this purpose
and end up assuming incorrectly that ->select_task_rq() was called for tasks
that are bound to a single CPU or migration disabled.
Make select_task_rq() indicate whether ->select_task_rq() was called by
setting WF_RQ_SELECTED in *wake_flags and make ttwu_do_activate() map that
to ENQUEUE_RQ_SELECTED for ->enqueue_task().
This will be used by sched_ext to fix ->select_task_rq() skip detection.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/core.c | 8 | ||||
| -rw-r--r-- | kernel/sched/sched.h | 3 |
2 files changed, 9 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e70b57a5693e..aeb595514461 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3522,10 +3522,12 @@ int select_task_rq(struct task_struct *p, int cpu, int *wake_flags) { lockdep_assert_held(&p->pi_lock); - if (p->nr_cpus_allowed > 1 && !is_migration_disabled(p)) + if (p->nr_cpus_allowed > 1 && !is_migration_disabled(p)) { cpu = p->sched_class->select_task_rq(p, cpu, *wake_flags); - else + *wake_flags |= WF_RQ_SELECTED; + } else { cpu = cpumask_any(p->cpus_ptr); + } /* * In order not to call set_task_cpu() on a blocking task we need @@ -3659,6 +3661,8 @@ ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags, rq->nr_uninterruptible--; #ifdef CONFIG_SMP + if (wake_flags & WF_RQ_SELECTED) + en_flags |= ENQUEUE_RQ_SELECTED; if (wake_flags & WF_MIGRATED) en_flags |= ENQUEUE_MIGRATED; else diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index b1c3588a8f00..6085ef50febf 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2292,6 +2292,7 @@ static inline int task_on_rq_migrating(struct task_struct *p) #define WF_SYNC 0x10 /* Waker goes to sleep after wakeup */ #define WF_MIGRATED 0x20 /* Internal use, task got migrated */ #define WF_CURRENT_CPU 0x40 /* Prefer to move the wakee to the current CPU. */ +#define WF_RQ_SELECTED 0x80 /* ->select_task_rq() was called */ #ifdef CONFIG_SMP static_assert(WF_EXEC == SD_BALANCE_EXEC); @@ -2334,6 +2335,7 @@ extern const u32 sched_prio_to_wmult[40]; * ENQUEUE_HEAD - place at front of runqueue (tail if not specified) * ENQUEUE_REPLENISH - CBS (replenish runtime and postpone deadline) * ENQUEUE_MIGRATED - the task was migrated during wakeup + * ENQUEUE_RQ_SELECTED - ->select_task_rq() was called * */ @@ -2360,6 +2362,7 @@ extern const u32 sched_prio_to_wmult[40]; #define ENQUEUE_INITIAL 0x80 #define ENQUEUE_MIGRATING 0x100 #define ENQUEUE_DELAYED 0x200 +#define ENQUEUE_RQ_SELECTED 0x400 #define RETRY_TASK ((void *)-1UL) |