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Commit 1a682754 authored by Paul E. McKenney's avatar Paul E. McKenney
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rcutorture: Print histogram of CB invocation at OOM time 



One reason why a forward-progress test might fail would be if something
prevented or delayed callback invocation.  This commit therefore adds a
callback-invocation histogram printout when OOM is reported to rcutorture.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.ibm.com>
parent 8dd3b546

kernel/rcu/rcutorture.c

+16 −8
Original line number Diff line number Diff line
@@ -1631,6 +1631,20 @@ static bool rcu_fwd_emergency_stop; 
#define MIN_FWD_CBS_LAUNDERED	100	/* Number of counted CBs. */

static long n_launders_hist[2 * MAX_FWD_CB_JIFFIES / HZ];



static void rcu_torture_fwd_cb_hist(void)

{

	int i;

	int j;



	for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--)

		if (n_launders_hist[i] > 0)

			break;

	pr_alert("%s: Callback-invocation histogram:", __func__);

	for (j = 0; j <= i; j++)

		pr_cont(" %ds: %ld", j + 1, n_launders_hist[j]);

	pr_cont("\n");

}



/* Callback function for continuous-flood RCU callbacks. */

static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)

{
@@ -1718,7 +1732,6 @@ static void rcu_torture_fwd_prog_cr(void) 
	unsigned long cver;

	unsigned long gps;

	int i;

	int j;

	long n_launders;

	long n_launders_cb_snap;

	long n_launders_sa;
@@ -1791,13 +1804,7 @@ static void rcu_torture_fwd_prog_cr(void) 
			 n_launders + n_max_cbs - n_launders_cb_snap,

			 n_launders, n_launders_sa,

			 n_max_gps, n_max_cbs, cver, gps);

		for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--)

			if (n_launders_hist[i] > 0)

				break;

		pr_alert("Callback-invocation histogram:");

		for (j = 0; j <= i; j++)

			pr_cont(" %ds: %ld", j + 1, n_launders_hist[j]);

		pr_cont("\n");

		rcu_torture_fwd_cb_hist();

	}

}
@@ -1809,6 +1816,7 @@ static void rcu_torture_fwd_prog_cr(void) 
static int rcutorture_oom_notify(struct notifier_block *self,

				 unsigned long notused, void *nfreed)

{

	rcu_torture_fwd_cb_hist();

	rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat) / 2));

	WRITE_ONCE(rcu_fwd_emergency_stop, true);

	return NOTIFY_OK;