Commit ed0d0db0 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Joel Fernandes
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rcutorture: Comment invocations of tick_dep_set_task() 



The rcu_torture_reader() and rcu_torture_fwd_prog_cr() functions
run CPU-bound for extended periods of time (tens or even
hundreds of milliseconds), so they invoke tick_dep_set_task() and
tick_dep_clear_task() to ensure that the scheduling-clock tick helps
move grace periods forward.

So why doesn't rcu_torture_fwd_prog_nr() also invoke tick_dep_set_task()
and tick_dep_clear_task()?  Because the point of this function is to test
RCU's ability to (eventually) force grace periods forward even when the
tick has been disabled during long CPU-bound kernel execution.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarJoel Fernandes <joelagnelf@nvidia.com>
parent a3204f77

kernel/rcu/rcutorture.c

+2 −2
Original line number Diff line number Diff line
@@ -2345,7 +2345,7 @@ rcu_torture_reader(void *arg) 
	set_user_nice(current, MAX_NICE);

	if (irqreader && cur_ops->irq_capable)

		timer_setup_on_stack(&t, rcu_torture_timer, 0);

	tick_dep_set_task(current, TICK_DEP_BIT_RCU);

	tick_dep_set_task(current, TICK_DEP_BIT_RCU);  // CPU bound, so need tick.

	do {

		if (irqreader && cur_ops->irq_capable) {

			if (!timer_pending(&t))
@@ -3074,7 +3074,7 @@ static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp) 
	cver = READ_ONCE(rcu_torture_current_version);

	gps = cur_ops->get_gp_seq();

	rfp->rcu_launder_gp_seq_start = gps;

	tick_dep_set_task(current, TICK_DEP_BIT_RCU);

	tick_dep_set_task(current, TICK_DEP_BIT_RCU);  // CPU bound, so need tick.

	while (time_before(jiffies, stopat) &&

	       !shutdown_time_arrived() &&

	       !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {