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rcutorture: Print histogram of CB invocation at OOM time

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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: Paul E. McKenney <paulmck@linux.ibm.com>
This commit is contained in:
Paul E. McKenney 2018-10-03 12:33:41 -07:00
parent 8dd3b54689
commit 1a682754c7
1 changed files with 16 additions and 8 deletions
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24
kernel/rcu/rcutorture.c
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@ -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;