From: "Uladzislau Rezki (Sony)" <urezki@xxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx> Link: https://lore.kernel.org/r/20250227131613.52683-1-urezki@xxxxxxxxx Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx> --- kernel/rcu/rcutorture.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index d26fb1d33ed9..726c2d63ab66 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -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)) -- 2.48.1
