rcutorture: Permit holding off CPU-hotplug operations during boot (9b9ec9b9) · Commits · 戴 / test

Documentation/RCU/torture.txt

+11 −2

Original line number	Diff line number	Diff line
		@@ -69,6 +69,13 @@ onoff_interval
		CPU-hotplug operations regardless of what value is
		specified for onoff_interval.

		onoff_holdoff The number of seconds to wait until starting CPU-hotplug
		operations. This would normally only be used when
		rcutorture was built into the kernel and started
		automatically at boot time, in which case it is useful
		in order to avoid confusing boot-time code with CPUs
		coming and going.

		shuffle_interval
		The number of seconds to keep the test threads affinitied
		to a particular subset of the CPUs, defaults to 3 seconds.
		@@ -277,5 +284,7 @@ The following script may be used to torture RCU:

		The output can be manually inspected for the error flag of "!!!".
		One could of course create a more elaborate script that automatically
		checked for such errors. The "rmmod" command forces a "SUCCESS" or
		"FAILURE" indication to be printk()ed.
		checked for such errors. The "rmmod" command forces a "SUCCESS",
		"FAILURE", or "RCU_HOTPLUG" indication to be printk()ed. The first
		two are self-explanatory, while the last indicates that while there
		were no RCU failures, CPU-hotplug problems were detected.

kernel/rcutorture.c

+10 −2

Original line number	Diff line number	Diff line
		@@ -65,6 +65,7 @@ static int fqs_duration; /* Duration of bursts (us), 0 to disable. */
		static int fqs_holdoff; /* Hold time within burst (us). */
		static int fqs_stutter = 3; /* Wait time between bursts (s). */
		static int onoff_interval; /* Wait time between CPU hotplugs, 0=disable. */
		static int onoff_holdoff; /* Seconds after boot before CPU hotplugs. */
		static int shutdown_secs; /* Shutdown time (s). <=0 for no shutdown. */
		static int test_boost = 1; /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
		static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
		@@ -95,6 +96,8 @@ module_param(fqs_stutter, int, 0444);
		MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
		module_param(onoff_interval, int, 0444);
		MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
		module_param(onoff_holdoff, int, 0444);
		MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)");
		module_param(shutdown_secs, int, 0444);
		MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), zero to disable.");
		module_param(test_boost, int, 0444);
		@@ -1300,13 +1303,13 @@ rcu_torture_print_module_parms(struct rcu_torture_ops cur_ops, char tag)
		"fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
		"test_boost=%d/%d test_boost_interval=%d "
		"test_boost_duration=%d shutdown_secs=%d "
		"onoff_interval=%d\n",
		"onoff_interval=%d onoff_holdoff=%d\n",
		torture_type, tag, nrealreaders, nfakewriters,
		stat_interval, verbose, test_no_idle_hz, shuffle_interval,
		stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
		test_boost, cur_ops->can_boost,
		test_boost_interval, test_boost_duration, shutdown_secs,
		onoff_interval);
		onoff_interval, onoff_holdoff);
		}

		static struct notifier_block rcutorture_shutdown_nb = {
		@@ -1410,6 +1413,11 @@ rcu_torture_onoff(void *arg)
		for_each_online_cpu(cpu)
		maxcpu = cpu;
		WARN_ON(maxcpu < 0);
		if (onoff_holdoff > 0) {
		VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
		schedule_timeout_interruptible(onoff_holdoff * HZ);
		VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
		}
		while (!kthread_should_stop()) {
		cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
		if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {

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