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rcutorture: Allow a negative value for nfakewriters

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Currently "nfakewriters" parameter can be set to any value but
there is no possibility to adjust it automatically based on how
many CPUs a system has where a test is run on.

To address this, if the "nfakewriters" is set to negative it will
be adjusted to num_online_cpus() during torture initialization.

Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Link: https://lore.kernel.org/r/20250227131613.52683-1-urezki@gmail.com
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
This commit is contained in:
Uladzislau Rezki (Sony) 2025-02-27 14:16:11 +01:00 committed by Boqun Feng
parent 6ea9a1781c
commit 8d67c1558a
1 changed files with 16 additions and 6 deletions
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22
kernel/rcu/rcutorture.c
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@ -147,6 +147,7 @@ MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
static int nrealnocbers;
static int nrealreaders;
static int nrealfakewriters;
static struct task_struct *writer_task;
static struct task_struct **fakewriter_tasks;
static struct task_struct **reader_tasks;
@ -1728,7 +1729,7 @@ rcu_torture_fakewriter(void *arg)
do {
torture_hrtimeout_jiffies(torture_random(&rand) % 10, &rand);
if (cur_ops->cb_barrier != NULL &&
torture_random(&rand) % (nfakewriters * 8) == 0) {
torture_random(&rand) % (nrealfakewriters * 8) == 0) {
cur_ops->cb_barrier();
} else {
switch (synctype[torture_random(&rand) % nsynctypes]) {
@ -2522,7 +2523,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
"nocbs_nthreads=%d nocbs_toggle=%d "
"test_nmis=%d "
"preempt_duration=%d preempt_interval=%d\n",
torture_type, tag, nrealreaders, nfakewriters,
torture_type, tag, nrealreaders, nrealfakewriters,
stat_interval, verbose, test_no_idle_hz, shuffle_interval,
stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
test_boost, cur_ops->can_boost,
@ -3597,7 +3598,7 @@ rcu_torture_cleanup(void)
rcu_torture_reader_mbchk = NULL;
if (fakewriter_tasks) {
for (i = 0; i < nfakewriters; i++)
for (i = 0; i < nrealfakewriters; i++)
torture_stop_kthread(rcu_torture_fakewriter,
fakewriter_tasks[i]);
kfree(fakewriter_tasks);
@ -3994,6 +3995,14 @@ rcu_torture_init(void)
rcu_torture_init_srcu_lockdep();
if (nfakewriters >= 0) {
nrealfakewriters = nfakewriters;
} else {
nrealfakewriters = num_online_cpus() - 2 - nfakewriters;
if (nrealfakewriters <= 0)
nrealfakewriters = 1;
}
if (nreaders >= 0) {
nrealreaders = nreaders;
} else {
@ -4050,8 +4059,9 @@ rcu_torture_init(void)
writer_task);
if (torture_init_error(firsterr))
goto unwind;
if (nfakewriters > 0) {
fakewriter_tasks = kcalloc(nfakewriters,
if (nrealfakewriters > 0) {
fakewriter_tasks = kcalloc(nrealfakewriters,
sizeof(fakewriter_tasks[0]),
GFP_KERNEL);
if (fakewriter_tasks == NULL) {
@ -4060,7 +4070,7 @@ rcu_torture_init(void)
goto unwind;
}
}
for (i = 0; i < nfakewriters; i++) {
for (i = 0; i < nrealfakewriters; i++) {
firsterr = torture_create_kthread(rcu_torture_fakewriter,
NULL, fakewriter_tasks[i]);
if (torture_init_error(firsterr))