[tip/core/rcu,04/12] rcutorture: Force on tick for readers and callback flooders
diff mbox series

Message ID 20191003013903.13079-4-paulmck@kernel.org
State New
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Series
  • NO_HZ fixes for v5.5
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Commit Message

Paul E. McKenney Oct. 3, 2019, 1:38 a.m. UTC
From: "Paul E. McKenney" <paulmck@linux.ibm.com>

Readers and callback flooders in the rcutorture stress-test suite run for
extended time periods by design.  They do take pains to relinquish the
CPU from time to time, but in some cases this relies on the scheduler
being active, which in turn relies on the scheduler-clock interrupt
firing from time to time.

This commit therefore forces scheduling-clock interrupts within
these loops.  While in the area, this commit also prevents
rcu_torture_reader()'s occasional timed sleeps from delaying shutdown.

[ paulmck: Apply Joel Fernandes TICK_DEP_MASK_RCU->TICK_DEP_BIT_RCU fix. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
---
 kernel/rcu/rcutorture.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

Comments

Frederic Weisbecker Oct. 3, 2019, 2:14 p.m. UTC | #1
On Wed, Oct 02, 2019 at 06:38:55PM -0700, paulmck@kernel.org wrote:
> From: "Paul E. McKenney" <paulmck@linux.ibm.com>
> 
> Readers and callback flooders in the rcutorture stress-test suite run for
> extended time periods by design.  They do take pains to relinquish the
> CPU from time to time, but in some cases this relies on the scheduler
> being active, which in turn relies on the scheduler-clock interrupt
> firing from time to time.
> 
> This commit therefore forces scheduling-clock interrupts within
> these loops.  While in the area, this commit also prevents
> rcu_torture_reader()'s occasional timed sleeps from delaying shutdown.
> 
> [ paulmck: Apply Joel Fernandes TICK_DEP_MASK_RCU->TICK_DEP_BIT_RCU fix. ]
> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

You can also remove all the IS_ENABLED here.

Thanks!
Paul E. McKenney Oct. 5, 2019, 4:52 p.m. UTC | #2
On Thu, Oct 03, 2019 at 04:14:58PM +0200, Frederic Weisbecker wrote:
> On Wed, Oct 02, 2019 at 06:38:55PM -0700, paulmck@kernel.org wrote:
> > From: "Paul E. McKenney" <paulmck@linux.ibm.com>
> > 
> > Readers and callback flooders in the rcutorture stress-test suite run for
> > extended time periods by design.  They do take pains to relinquish the
> > CPU from time to time, but in some cases this relies on the scheduler
> > being active, which in turn relies on the scheduler-clock interrupt
> > firing from time to time.
> > 
> > This commit therefore forces scheduling-clock interrupts within
> > these loops.  While in the area, this commit also prevents
> > rcu_torture_reader()'s occasional timed sleeps from delaying shutdown.
> > 
> > [ paulmck: Apply Joel Fernandes TICK_DEP_MASK_RCU->TICK_DEP_BIT_RCU fix. ]
> > Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
> 
> You can also remove all the IS_ENABLED here.

Again, good catch and fixed, thank you!

							Thanx, Paul

Patch
diff mbox series

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 3c9feca..1ce6a7e 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -44,6 +44,7 @@ 
 #include <linux/sched/debug.h>
 #include <linux/sched/sysctl.h>
 #include <linux/oom.h>
+#include <linux/tick.h>
 
 #include "rcu.h"
 
@@ -1363,15 +1364,16 @@  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);
-
+	if (IS_ENABLED(CONFIG_NO_HZ_FULL))
+		tick_dep_set_task(current, TICK_DEP_BIT_RCU);
 	do {
 		if (irqreader && cur_ops->irq_capable) {
 			if (!timer_pending(&t))
 				mod_timer(&t, jiffies + 1);
 		}
-		if (!rcu_torture_one_read(&rand))
+		if (!rcu_torture_one_read(&rand) && !torture_must_stop())
 			schedule_timeout_interruptible(HZ);
-		if (time_after(jiffies, lastsleep)) {
+		if (time_after(jiffies, lastsleep) && !torture_must_stop()) {
 			schedule_timeout_interruptible(1);
 			lastsleep = jiffies + 10;
 		}
@@ -1383,6 +1385,8 @@  rcu_torture_reader(void *arg)
 		del_timer_sync(&t);
 		destroy_timer_on_stack(&t);
 	}
+	if (IS_ENABLED(CONFIG_NO_HZ_FULL))
+		tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
 	torture_kthread_stopping("rcu_torture_reader");
 	return 0;
 }
@@ -1729,10 +1733,10 @@  static void rcu_torture_fwd_prog_cond_resched(unsigned long iter)
 		// Real call_rcu() floods hit userspace, so emulate that.
 		if (need_resched() || (iter & 0xfff))
 			schedule();
-	} else {
-		// No userspace emulation: CB invocation throttles call_rcu()
-		cond_resched();
+		return;
 	}
+	// No userspace emulation: CB invocation throttles call_rcu()
+	cond_resched();
 }
 
 /*
@@ -1865,6 +1869,8 @@  static void rcu_torture_fwd_prog_cr(void)
 	cver = READ_ONCE(rcu_torture_current_version);
 	gps = cur_ops->get_gp_seq();
 	rcu_launder_gp_seq_start = gps;
+	if (IS_ENABLED(CONFIG_NO_HZ_FULL))
+		tick_dep_set_task(current, TICK_DEP_BIT_RCU);
 	while (time_before(jiffies, stopat) &&
 	       !shutdown_time_arrived() &&
 	       !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
@@ -1911,6 +1917,8 @@  static void rcu_torture_fwd_prog_cr(void)
 		rcu_torture_fwd_cb_hist();
 	}
 	schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
+	if (IS_ENABLED(CONFIG_NO_HZ_FULL))
+		tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
 	WRITE_ONCE(rcu_fwd_cb_nodelay, false);
 }