The following commit has been merged into the core/rcu branch of tip:
Commit-ID: e76506f0e85129d726c487c873a2245c92446515
Gitweb:
https://git.kernel.org/tip/e76506f0e85129d726c487c873a2245c92446515
Author: Paul E. McKenney <paul...@kernel.org>
AuthorDate: Sun, 15 Nov 2020 10:24:52 -08:00
Committer: Paul E. McKenney <paul...@kernel.org>
CommitterDate: Wed, 06 Jan 2021 17:08:09 -08:00
refscale: Allow summarization of verbose output
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 <paul...@kernel.org>
---
Documentation/admin-guide/kernel-parameters.txt | 6 +++++-
kernel/rcu/refscale.c | 21 ++++++++++++----
2 files changed, 22 insertions(+), 5 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt
b/Documentation/admin-guide/kernel-parameters.txt
index c722ec1..3244f9e 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -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.
diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index 23ff36a..3da246f 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -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;
