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refscale: Allow summarization of verbose output

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The refscale test prints enough per-kthread console output to provoke RCU
CPU stall warnings on large systems.  This commit therefore allows this
output to be summarized.  For example, the refscale.verbose_batched=32
boot parameter would causes only every 32nd line of output to be logged.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2020-11-15 10:24:52 -08:00
parent f3ea978b71
commit e76506f0e8
2 changed files with 22 additions and 5 deletions
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6
Documentation/admin-guide/kernel-parameters.txt
View File

@ -4557,6 +4557,12 @@
refscale.verbose= [KNL]
Enable additional printk() statements.
refscale.verbose_batched= [KNL]
Batch the additional printk() statements. If zero
(the default) or negative, print everything. Otherwise,
print every Nth verbose statement, where N is the value
specified.
relax_domain_level=
[KNL, SMP] Set scheduler's default relax_domain_level.
See Documentation/admin-guide/cgroup-v1/cpusets.rst.

21
kernel/rcu/refscale.c
View File

@ -46,6 +46,16 @@
#define VERBOSE_SCALEOUT(s, x...) \
do { if (verbose) pr_alert("%s" SCALE_FLAG s, scale_type, ## x); } while (0)
static atomic_t verbose_batch_ctr;
#define VERBOSE_SCALEOUT_BATCH(s, x...) \
do { \
if (verbose && \
(verbose_batched <= 0 || \
!(atomic_inc_return(&verbose_batch_ctr) % verbose_batched))) \
pr_alert("%s" SCALE_FLAG s, scale_type, ## x); \
} while (0)
#define VERBOSE_SCALEOUT_ERRSTRING(s, x...) \
do { if (verbose) pr_alert("%s" SCALE_FLAG "!!! " s, scale_type, ## x); } while (0)
@ -57,6 +67,7 @@ module_param(scale_type, charp, 0444);
MODULE_PARM_DESC(scale_type, "Type of test (rcu, srcu, refcnt, rwsem, rwlock.");
torture_param(int, verbose, 0, "Enable verbose debugging printk()s");
torture_param(int, verbose_batched, 0, "Batch verbose debugging printk()s");
// Wait until there are multiple CPUs before starting test.
torture_param(int, holdoff, IS_BUILTIN(CONFIG_RCU_REF_SCALE_TEST) ? 10 : 0,
@ -368,14 +379,14 @@ ref_scale_reader(void *arg)
u64 start;
s64 duration;
VERBOSE_SCALEOUT("ref_scale_reader %ld: task started", me);
VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: task started", me);
set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
set_user_nice(current, MAX_NICE);
atomic_inc(&n_init);
if (holdoff)
schedule_timeout_interruptible(holdoff * HZ);
repeat:
VERBOSE_SCALEOUT("ref_scale_reader %ld: waiting to start next experiment on cpu %d", me, smp_processor_id());
VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: waiting to start next experiment on cpu %d", me, smp_processor_id());
// Wait for signal that this reader can start.
wait_event(rt->wq, (atomic_read(&nreaders_exp) && smp_load_acquire(&rt->start_reader)) ||
@ -392,7 +403,7 @@ repeat:
while (atomic_read_acquire(&n_started))
cpu_relax();
VERBOSE_SCALEOUT("ref_scale_reader %ld: experiment %d started", me, exp_idx);
VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: experiment %d started", me, exp_idx);
// To reduce noise, do an initial cache-warming invocation, check
@ -421,8 +432,8 @@ repeat:
if (atomic_dec_and_test(&nreaders_exp))
wake_up(&main_wq);
VERBOSE_SCALEOUT("ref_scale_reader %ld: experiment %d ended, (readers remaining=%d)",
me, exp_idx, atomic_read(&nreaders_exp));
VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: experiment %d ended, (readers remaining=%d)",
me, exp_idx, atomic_read(&nreaders_exp));
if (!torture_must_stop())
goto repeat;