From 777a54c908ec69fa0eccab54068a49ecda38ffde Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 25 May 2020 14:16:44 -0700 Subject: refperf: Add holdoff parameter to allow CPUs to come online This commit adds an rcuperf module parameter named "holdoff" that defaults to 10 seconds if refperf is built in and to zero otherwise. The assumption is that all the CPUs are online by the time that the modprobe and insmod commands are going to do anything, and that normal systems will have all the CPUs online within ten seconds. Larger systems may take many tens of seconds or even minutes to get to this point, hence this being a module parameter instead of being a hard-coded constant. Cc: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney --- kernel/rcu/refperf.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'kernel/rcu') diff --git a/kernel/rcu/refperf.c b/kernel/rcu/refperf.c index 61161530acc8..4d686fdc3105 100644 --- a/kernel/rcu/refperf.c +++ b/kernel/rcu/refperf.c @@ -57,7 +57,10 @@ MODULE_PARM_DESC(perf_type, "Type of test (rcu, srcu, refcnt, rwsem, rwlock."); torture_param(int, verbose, 0, "Enable verbose debugging printk()s"); -// Number of loops per experiment, all readers execute an operation concurrently +// Wait until there are multiple CPUs before starting test. +torture_param(int, holdoff, IS_BUILTIN(CONFIG_RCU_REF_PERF_TEST) ? 10 : 0, + "Holdoff time before test start (s)"); +// Number of loops per experiment, all readers execute operations concurrently. torture_param(long, loops, 10000000, "Number of loops per experiment."); #ifdef MODULE @@ -248,6 +251,8 @@ ref_perf_reader(void *arg) 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_PERFOUT("ref_perf_reader %ld: waiting to start next experiment on cpu %d", me, smp_processor_id()); @@ -357,6 +362,8 @@ static int main_func(void *arg) // Wait for all threads to start. wait_event(main_wq, atomic_read(&n_init) == (nreaders + 1)); + if (holdoff) + schedule_timeout_interruptible(holdoff * HZ); // Start exp readers up per experiment for (exp = 0; exp < nreaders && !torture_must_stop(); exp++) { @@ -420,8 +427,8 @@ static void ref_perf_print_module_parms(struct ref_perf_ops *cur_ops, const char *tag) { pr_alert("%s" PERF_FLAG - "--- %s: verbose=%d shutdown=%d loops=%ld\n", perf_type, tag, - verbose, shutdown, loops); + "--- %s: verbose=%d shutdown=%d holdoff=%d loops=%ld\n", perf_type, tag, + verbose, shutdown, holdoff, loops); } static void -- cgit v1.2.3