Re: [PATCH v3 12/17] sched: Adapt sched tracepoints for RV task model
From: Peter Zijlstra <peterz@infradead.org>
Date: 2025-07-16 12:38:38
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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 switchquoted hunk ↗ jump to hunk
@@ -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() ?
quoted hunk ↗ jump to hunk
@@ -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.