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Commit a30489c5 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Paul E. McKenney
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rcu: Instrument synchronize_rcu_expedited() for debugfs tracing 



This commit adds the counters to rcu_state and updates them in
synchronize_rcu_expedited() to provide the data needed for debugfs
tracing.

Signed-off-by: default avatarPaul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 40694d66

kernel/rcutree.c

+15 −3
Original line number Diff line number Diff line
@@ -2321,6 +2321,7 @@ void synchronize_sched_expedited(void) 
			 (ulong)atomic_long_read(&rsp->expedited_done) +

			 ULONG_MAX / 8)) {

		synchronize_sched();

		atomic_long_inc(&rsp->expedited_wrap);

		return;

	}
@@ -2341,11 +2342,14 @@ void synchronize_sched_expedited(void) 
			     synchronize_sched_expedited_cpu_stop,

			     NULL) == -EAGAIN) {

		put_online_cpus();

		atomic_long_inc(&rsp->expedited_tryfail);



		/* Check to see if someone else did our work for us. */

		s = atomic_long_read(&rsp->expedited_done);

		if (ULONG_CMP_GE((ulong)s, (ulong)firstsnap)) {

			smp_mb(); /* ensure test happens before caller kfree */

			/* ensure test happens before caller kfree */

			smp_mb__before_atomic_inc(); /* ^^^ */

			atomic_long_inc(&rsp->expedited_workdone1);

			return;

		}
@@ -2354,13 +2358,16 @@ void synchronize_sched_expedited(void) 
			udelay(trycount * num_online_cpus());

		} else {

			synchronize_sched();

			atomic_long_inc(&rsp->expedited_normal);

			return;

		}



		/* Recheck to see if someone else did our work for us. */

		s = atomic_long_read(&rsp->expedited_done);

		if (ULONG_CMP_GE((ulong)s, (ulong)firstsnap)) {

			smp_mb(); /* ensure test happens before caller kfree */

			/* ensure test happens before caller kfree */

			smp_mb__before_atomic_inc(); /* ^^^ */

			atomic_long_inc(&rsp->expedited_workdone2);

			return;

		}
@@ -2375,6 +2382,7 @@ void synchronize_sched_expedited(void) 
		snap = atomic_long_read(&rsp->expedited_start);

		smp_mb(); /* ensure read is before try_stop_cpus(). */

	}

	atomic_long_inc(&rsp->expedited_stoppedcpus);



	/*

	 * Everyone up to our most recent fetch is covered by our grace
@@ -2383,12 +2391,16 @@ void synchronize_sched_expedited(void) 
	 * than we did already did their update.

	 */

	do {

		atomic_long_inc(&rsp->expedited_done_tries);

		s = atomic_long_read(&rsp->expedited_done);

		if (ULONG_CMP_GE((ulong)s, (ulong)snap)) {

			smp_mb(); /* ensure test happens before caller kfree */

			/* ensure test happens before caller kfree */

			smp_mb__before_atomic_inc(); /* ^^^ */

			atomic_long_inc(&rsp->expedited_done_lost);

			break;

		}

	} while (atomic_long_cmpxchg(&rsp->expedited_done, s, snap) != s);

	atomic_long_inc(&rsp->expedited_done_exit);



	put_online_cpus();

}

kernel/rcutree.h

+9 −0
Original line number Diff line number Diff line
@@ -406,6 +406,15 @@ struct rcu_state { 


	atomic_long_t expedited_start;		/* Starting ticket. */

	atomic_long_t expedited_done;		/* Done ticket. */

	atomic_long_t expedited_wrap;		/* # near-wrap incidents. */

	atomic_long_t expedited_tryfail;	/* # acquisition failures. */

	atomic_long_t expedited_workdone1;	/* # done by others #1. */

	atomic_long_t expedited_workdone2;	/* # done by others #2. */

	atomic_long_t expedited_normal;		/* # fallbacks to normal. */

	atomic_long_t expedited_stoppedcpus;	/* # successful stop_cpus. */

	atomic_long_t expedited_done_tries;	/* # tries to update _done. */

	atomic_long_t expedited_done_lost;	/* # times beaten to _done. */

	atomic_long_t expedited_done_exit;	/* # times exited _done loop. */



	unsigned long jiffies_force_qs;		/* Time at which to invoke */

						/*  force_quiescent_state(). */