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Commit 2e57bf97 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcutorture: Use 100ms buckets for forward-progress callback histograms 



This commit narrows the scope of each bucket of the forward-progress
callback-invocation histograms from one second to 100 milliseconds, which
aids debugging of forward-progress problems by making shorter-duration
callback-invocation stalls visible.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.ibm.com>
parent 2667ccce

kernel/rcu/rcutorture.c

+5 −3
Original line number Diff line number Diff line
@@ -1629,7 +1629,8 @@ static bool rcu_fwd_emergency_stop; 
#define MAX_FWD_CB_JIFFIES	(8 * HZ) /* Maximum CB test duration. */

#define MIN_FWD_CB_LAUNDERS	3	/* This many CB invocations to count. */

#define MIN_FWD_CBS_LAUNDERED	100	/* Number of counted CBs. */

static long n_launders_hist[2 * MAX_FWD_CB_JIFFIES / HZ];

#define FWD_CBS_HIST_DIV	10	/* Histogram buckets/second. */

static long n_launders_hist[2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV)];



static void rcu_torture_fwd_cb_hist(void)

{
@@ -1642,7 +1643,8 @@ static void rcu_torture_fwd_cb_hist(void) 
	pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",

		 __func__, jiffies - rcu_fwd_startat);

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

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

		pr_cont(" %ds/%d: %ld",

			j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j]);

	pr_cont("\n");

}
@@ -1661,7 +1663,7 @@ static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp) 
	rcu_fwd_cb_tail = &rfcp->rfc_next;

	WRITE_ONCE(*rfcpp, rfcp);

	WRITE_ONCE(n_launders_cb, n_launders_cb + 1);

	i = ((jiffies - rcu_fwd_startat) / HZ);

	i = ((jiffies - rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));

	if (i >= ARRAY_SIZE(n_launders_hist))

		i = ARRAY_SIZE(n_launders_hist) - 1;

	n_launders_hist[i]++;