On Tue, Jul 15, 2025 at 09:14:29AM +0200, Gabriele Monaco wrote:
> Add the following tracepoints:
> * sched_set_need_resched(tsk, cpu, tif)
> Called when a task is set the need resched [lazy] flag
> * sched_switch_vain(preempt, tsk, tsk_state)
> Called when a task is selected again during __schedule
> i.e. prev == next == tsk : no real context switch
> @@ -6592,6 +6598,7 @@ static bool try_to_block_task(struct rq *rq, struct
> task_struct *p,
> int flags = DEQUEUE_NOCLOCK;
>
> if (signal_pending_state(task_state, p)) {
> + trace_sched_set_state_tp(p, TASK_RUNNING, true);
> WRITE_ONCE(p->__state, TASK_RUNNING);
> *task_state_p = TASK_RUNNING;
> return false;
I'm confused on the purpose of this. How does this relate to say the
wakeup in signal_wake_up_state() ?
> @@ -6786,6 +6793,7 @@ static void __sched notrace __schedule(int sched_mode)
> rq = context_switch(rq, prev, next, &rf);
> } else {
> rq_unpin_lock(rq, &rf);
> + trace_sched_switch_vain_tp(preempt, prev, prev_state);
> __balance_callbacks(rq);
> raw_spin_rq_unlock_irq(rq);
> }
Hurmph... don't you already have this covered by: trace_sched_exit_tp() ?
Specifically, the only case where is_switch := false, is this case.
