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

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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: Paul E. McKenney <paulmck@linux.ibm.com>
This commit is contained in:
Paul E. McKenney 2018-10-05 16:43:09 -07:00
parent 2667ccce93
commit 2e57bf97a6
1 changed files with 5 additions and 3 deletions
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8
kernel/rcu/rcutorture.c
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@ -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]++;