diff options
| -rw-r--r-- | kernel/sched/ext.c | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 89bcca84d6b5..2e652f7b8f54 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -215,6 +215,72 @@ struct sched_ext_ops { void (*tick)(struct task_struct *p); /** + * runnable - A task is becoming runnable on its associated CPU + * @p: task becoming runnable + * @enq_flags: %SCX_ENQ_* + * + * This and the following three functions can be used to track a task's + * execution state transitions. A task becomes ->runnable() on a CPU, + * and then goes through one or more ->running() and ->stopping() pairs + * as it runs on the CPU, and eventually becomes ->quiescent() when it's + * done running on the CPU. + * + * @p is becoming runnable on the CPU because it's + * + * - waking up (%SCX_ENQ_WAKEUP) + * - being moved from another CPU + * - being restored after temporarily taken off the queue for an + * attribute change. + * + * This and ->enqueue() are related but not coupled. This operation + * notifies @p's state transition and may not be followed by ->enqueue() + * e.g. when @p is being dispatched to a remote CPU, or when @p is + * being enqueued on a CPU experiencing a hotplug event. Likewise, a + * task may be ->enqueue()'d without being preceded by this operation + * e.g. after exhausting its slice. + */ + void (*runnable)(struct task_struct *p, u64 enq_flags); + + /** + * running - A task is starting to run on its associated CPU + * @p: task starting to run + * + * See ->runnable() for explanation on the task state notifiers. + */ + void (*running)(struct task_struct *p); + + /** + * stopping - A task is stopping execution + * @p: task stopping to run + * @runnable: is task @p still runnable? + * + * See ->runnable() for explanation on the task state notifiers. If + * !@runnable, ->quiescent() will be invoked after this operation + * returns. + */ + void (*stopping)(struct task_struct *p, bool runnable); + + /** + * quiescent - A task is becoming not runnable on its associated CPU + * @p: task becoming not runnable + * @deq_flags: %SCX_DEQ_* + * + * See ->runnable() for explanation on the task state notifiers. + * + * @p is becoming quiescent on the CPU because it's + * + * - sleeping (%SCX_DEQ_SLEEP) + * - being moved to another CPU + * - being temporarily taken off the queue for an attribute change + * (%SCX_DEQ_SAVE) + * + * This and ->dequeue() are related but not coupled. This operation + * notifies @p's state transition and may not be preceded by ->dequeue() + * e.g. when @p is being dispatched to a remote CPU. + */ + void (*quiescent)(struct task_struct *p, u64 deq_flags); + + /** * yield - Yield CPU * @from: yielding task * @to: optional yield target task @@ -1359,6 +1425,9 @@ static void enqueue_task_scx(struct rq *rq, struct task_struct *p, int enq_flags rq->scx.nr_running++; add_nr_running(rq, 1); + if (SCX_HAS_OP(runnable)) + SCX_CALL_OP(SCX_KF_REST, runnable, p, enq_flags); + do_enqueue_task(rq, p, enq_flags, sticky_cpu); } @@ -1418,6 +1487,26 @@ static void dequeue_task_scx(struct rq *rq, struct task_struct *p, int deq_flags ops_dequeue(p, deq_flags); + /* + * A currently running task which is going off @rq first gets dequeued + * and then stops running. As we want running <-> stopping transitions + * to be contained within runnable <-> quiescent transitions, trigger + * ->stopping() early here instead of in put_prev_task_scx(). + * + * @p may go through multiple stopping <-> running transitions between + * here and put_prev_task_scx() if task attribute changes occur while + * balance_scx() leaves @rq unlocked. However, they don't contain any + * information meaningful to the BPF scheduler and can be suppressed by + * skipping the callbacks if the task is !QUEUED. + */ + if (SCX_HAS_OP(stopping) && task_current(rq, p)) { + update_curr_scx(rq); + SCX_CALL_OP(SCX_KF_REST, stopping, p, false); + } + + if (SCX_HAS_OP(quiescent)) + SCX_CALL_OP(SCX_KF_REST, quiescent, p, deq_flags); + if (deq_flags & SCX_DEQ_SLEEP) p->scx.flags |= SCX_TASK_DEQD_FOR_SLEEP; else @@ -1999,6 +2088,10 @@ static void set_next_task_scx(struct rq *rq, struct task_struct *p, bool first) p->se.exec_start = rq_clock_task(rq); + /* see dequeue_task_scx() on why we skip when !QUEUED */ + if (SCX_HAS_OP(running) && (p->scx.flags & SCX_TASK_QUEUED)) + SCX_CALL_OP(SCX_KF_REST, running, p); + clr_task_runnable(p, true); } @@ -2037,6 +2130,10 @@ static void put_prev_task_scx(struct rq *rq, struct task_struct *p) update_curr_scx(rq); + /* see dequeue_task_scx() on why we skip when !QUEUED */ + if (SCX_HAS_OP(stopping) && (p->scx.flags & SCX_TASK_QUEUED)) + SCX_CALL_OP(SCX_KF_REST, stopping, p, true); + /* * If we're being called from put_prev_task_balance(), balance_scx() may * have decided that @p should keep running. @@ -4081,6 +4178,10 @@ static s32 select_cpu_stub(struct task_struct *p, s32 prev_cpu, u64 wake_flags) static void enqueue_stub(struct task_struct *p, u64 enq_flags) {} static void dequeue_stub(struct task_struct *p, u64 enq_flags) {} static void dispatch_stub(s32 prev_cpu, struct task_struct *p) {} +static void runnable_stub(struct task_struct *p, u64 enq_flags) {} +static void running_stub(struct task_struct *p) {} +static void stopping_stub(struct task_struct *p, bool runnable) {} +static void quiescent_stub(struct task_struct *p, u64 deq_flags) {} static bool yield_stub(struct task_struct *from, struct task_struct *to) { return false; } static void set_weight_stub(struct task_struct *p, u32 weight) {} static void set_cpumask_stub(struct task_struct *p, const struct cpumask *mask) {} @@ -4097,6 +4198,10 @@ static struct sched_ext_ops __bpf_ops_sched_ext_ops = { .enqueue = enqueue_stub, .dequeue = dequeue_stub, .dispatch = dispatch_stub, + .runnable = runnable_stub, + .running = running_stub, + .stopping = stopping_stub, + .quiescent = quiescent_stub, .yield = yield_stub, .set_weight = set_weight_stub, .set_cpumask = set_cpumask_stub, |