rcu: add priority-inversion testing to rcutorture
Add an optional test to force long-term preemption of RCU read-side critical sections, controlled by new test_boost, test_boost_interval, and test_boost_duration module parameters. This is to be used to test RCU priority boosting. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney
parent
6506cf6ce6
commit
8e8be45e8e
1 changed files with 259 additions and 11 deletions
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@ -47,6 +47,7 @@
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#include <linux/srcu.h>
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#include <linux/slab.h>
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#include <asm/byteorder.h>
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#include <linux/sched.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
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@ -64,6 +65,9 @@ static int irqreader = 1; /* RCU readers from irq (timers). */
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static int fqs_duration = 0; /* Duration of bursts (us), 0 to disable. */
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static int fqs_holdoff = 0; /* Hold time within burst (us). */
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static int fqs_stutter = 3; /* Wait time between bursts (s). */
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static int test_boost = 1; /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
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static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
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static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
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static char *torture_type = "rcu"; /* What RCU implementation to torture. */
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module_param(nreaders, int, 0444);
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@ -88,6 +92,12 @@ module_param(fqs_holdoff, int, 0444);
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MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
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module_param(fqs_stutter, int, 0444);
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MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
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module_param(test_boost, int, 0444);
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MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
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module_param(test_boost_interval, int, 0444);
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MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
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module_param(test_boost_duration, int, 0444);
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MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
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module_param(torture_type, charp, 0444);
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MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
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@ -109,6 +119,7 @@ static struct task_struct *stats_task;
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static struct task_struct *shuffler_task;
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static struct task_struct *stutter_task;
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static struct task_struct *fqs_task;
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static struct task_struct *boost_tasks[NR_CPUS];
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#define RCU_TORTURE_PIPE_LEN 10
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@ -134,6 +145,12 @@ static atomic_t n_rcu_torture_alloc_fail;
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static atomic_t n_rcu_torture_free;
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static atomic_t n_rcu_torture_mberror;
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static atomic_t n_rcu_torture_error;
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static long n_rcu_torture_boost_ktrerror;
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static long n_rcu_torture_boost_rterror;
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static long n_rcu_torture_boost_allocerror;
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static long n_rcu_torture_boost_afferror;
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static long n_rcu_torture_boost_failure;
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static long n_rcu_torture_boosts;
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static long n_rcu_torture_timers;
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static struct list_head rcu_torture_removed;
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static cpumask_var_t shuffle_tmp_mask;
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@ -147,6 +164,16 @@ static int stutter_pause_test;
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#endif
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int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
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#ifdef CONFIG_RCU_BOOST
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#define rcu_can_boost() 1
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#else /* #ifdef CONFIG_RCU_BOOST */
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#define rcu_can_boost() 0
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#endif /* #else #ifdef CONFIG_RCU_BOOST */
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static unsigned long boost_starttime; /* jiffies of next boost test start. */
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DEFINE_MUTEX(boost_mutex); /* protect setting boost_starttime */
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/* and boost task create/destroy. */
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/* Mediate rmmod and system shutdown. Concurrent rmmod & shutdown illegal! */
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#define FULLSTOP_DONTSTOP 0 /* Normal operation. */
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@ -277,6 +304,7 @@ struct rcu_torture_ops {
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void (*fqs)(void);
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int (*stats)(char *page);
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int irq_capable;
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int can_boost;
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char *name;
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};
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@ -366,6 +394,7 @@ static struct rcu_torture_ops rcu_ops = {
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.fqs = rcu_force_quiescent_state,
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.stats = NULL,
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.irq_capable = 1,
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.can_boost = rcu_can_boost(),
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.name = "rcu"
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};
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@ -408,6 +437,7 @@ static struct rcu_torture_ops rcu_sync_ops = {
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.fqs = rcu_force_quiescent_state,
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.stats = NULL,
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.irq_capable = 1,
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.can_boost = rcu_can_boost(),
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.name = "rcu_sync"
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};
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@ -424,6 +454,7 @@ static struct rcu_torture_ops rcu_expedited_ops = {
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.fqs = rcu_force_quiescent_state,
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.stats = NULL,
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.irq_capable = 1,
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.can_boost = rcu_can_boost(),
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.name = "rcu_expedited"
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};
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@ -683,6 +714,110 @@ static struct rcu_torture_ops sched_expedited_ops = {
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.name = "sched_expedited"
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};
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/*
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* RCU torture priority-boost testing. Runs one real-time thread per
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* CPU for moderate bursts, repeatedly registering RCU callbacks and
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* spinning waiting for them to be invoked. If a given callback takes
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* too long to be invoked, we assume that priority inversion has occurred.
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*/
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struct rcu_boost_inflight {
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struct rcu_head rcu;
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int inflight;
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};
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static void rcu_torture_boost_cb(struct rcu_head *head)
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{
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struct rcu_boost_inflight *rbip =
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container_of(head, struct rcu_boost_inflight, rcu);
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smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
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rbip->inflight = 0;
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}
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static int rcu_torture_boost(void *arg)
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{
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unsigned long call_rcu_time;
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unsigned long endtime;
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unsigned long oldstarttime;
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struct rcu_boost_inflight rbi = { .inflight = 0 };
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struct sched_param sp;
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VERBOSE_PRINTK_STRING("rcu_torture_boost started");
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/* Set real-time priority. */
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sp.sched_priority = 1;
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if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
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VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
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n_rcu_torture_boost_rterror++;
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}
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/* Each pass through the following loop does one boost-test cycle. */
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do {
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/* Wait for the next test interval. */
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oldstarttime = boost_starttime;
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while (jiffies - oldstarttime > ULONG_MAX / 2) {
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schedule_timeout_uninterruptible(1);
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rcu_stutter_wait("rcu_torture_boost");
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if (kthread_should_stop() ||
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fullstop != FULLSTOP_DONTSTOP)
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goto checkwait;
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}
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/* Do one boost-test interval. */
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endtime = oldstarttime + test_boost_duration * HZ;
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call_rcu_time = jiffies;
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while (jiffies - endtime > ULONG_MAX / 2) {
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/* If we don't have a callback in flight, post one. */
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if (!rbi.inflight) {
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smp_mb(); /* RCU core before ->inflight = 1. */
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rbi.inflight = 1;
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call_rcu(&rbi.rcu, rcu_torture_boost_cb);
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if (jiffies - call_rcu_time >
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test_boost_duration * HZ - HZ / 2) {
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VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
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n_rcu_torture_boost_failure++;
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}
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call_rcu_time = jiffies;
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}
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cond_resched();
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rcu_stutter_wait("rcu_torture_boost");
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if (kthread_should_stop() ||
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fullstop != FULLSTOP_DONTSTOP)
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goto checkwait;
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}
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/*
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* Set the start time of the next test interval.
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* Yes, this is vulnerable to long delays, but such
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* delays simply cause a false negative for the next
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* interval. Besides, we are running at RT priority,
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* so delays should be relatively rare.
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*/
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while (oldstarttime == boost_starttime) {
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if (mutex_trylock(&boost_mutex)) {
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boost_starttime = jiffies +
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test_boost_interval * HZ;
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n_rcu_torture_boosts++;
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mutex_unlock(&boost_mutex);
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break;
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}
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schedule_timeout_uninterruptible(1);
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}
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/* Go do the stutter. */
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checkwait: rcu_stutter_wait("rcu_torture_boost");
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} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
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/* Clean up and exit. */
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VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
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rcutorture_shutdown_absorb("rcu_torture_boost");
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while (!kthread_should_stop() || rbi.inflight)
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schedule_timeout_uninterruptible(1);
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smp_mb(); /* order accesses to ->inflight before stack-frame death. */
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return 0;
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}
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/*
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* RCU torture force-quiescent-state kthread. Repeatedly induces
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* bursts of calls to force_quiescent_state(), increasing the probability
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@ -933,7 +1068,8 @@ rcu_torture_printk(char *page)
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cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
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cnt += sprintf(&page[cnt],
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"rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
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"rtmbe: %d nt: %ld",
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"rtmbe: %d rtbke: %ld rtbre: %ld rtbae: %ld rtbafe: %ld "
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"rtbf: %ld rtb: %ld nt: %ld",
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rcu_torture_current,
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rcu_torture_current_version,
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list_empty(&rcu_torture_freelist),
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@ -941,8 +1077,19 @@ rcu_torture_printk(char *page)
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atomic_read(&n_rcu_torture_alloc_fail),
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atomic_read(&n_rcu_torture_free),
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atomic_read(&n_rcu_torture_mberror),
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n_rcu_torture_boost_ktrerror,
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n_rcu_torture_boost_rterror,
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n_rcu_torture_boost_allocerror,
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n_rcu_torture_boost_afferror,
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n_rcu_torture_boost_failure,
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n_rcu_torture_boosts,
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n_rcu_torture_timers);
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if (atomic_read(&n_rcu_torture_mberror) != 0)
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if (atomic_read(&n_rcu_torture_mberror) != 0 ||
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n_rcu_torture_boost_ktrerror != 0 ||
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n_rcu_torture_boost_rterror != 0 ||
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n_rcu_torture_boost_allocerror != 0 ||
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n_rcu_torture_boost_afferror != 0 ||
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n_rcu_torture_boost_failure != 0)
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cnt += sprintf(&page[cnt], " !!!");
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cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
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if (i > 1) {
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@ -1094,22 +1241,91 @@ rcu_torture_stutter(void *arg)
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}
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static inline void
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rcu_torture_print_module_parms(char *tag)
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rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
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{
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printk(KERN_ALERT "%s" TORTURE_FLAG
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"--- %s: nreaders=%d nfakewriters=%d "
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"stat_interval=%d verbose=%d test_no_idle_hz=%d "
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"shuffle_interval=%d stutter=%d irqreader=%d "
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"fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d\n",
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"fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
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"test_boost=%d/%d test_boost_interval=%d "
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"test_boost_duration=%d\n",
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torture_type, tag, nrealreaders, nfakewriters,
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stat_interval, verbose, test_no_idle_hz, shuffle_interval,
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stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter);
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stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
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test_boost, cur_ops->can_boost,
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test_boost_interval, test_boost_duration);
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}
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static struct notifier_block rcutorture_nb = {
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static struct notifier_block rcutorture_shutdown_nb = {
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.notifier_call = rcutorture_shutdown_notify,
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};
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static void rcutorture_booster_cleanup(int cpu)
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{
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struct task_struct *t;
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if (boost_tasks[cpu] == NULL)
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return;
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mutex_lock(&boost_mutex);
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VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
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t = boost_tasks[cpu];
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boost_tasks[cpu] = NULL;
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mutex_unlock(&boost_mutex);
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/* This must be outside of the mutex, otherwise deadlock! */
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kthread_stop(t);
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}
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static int rcutorture_booster_init(int cpu)
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{
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int retval;
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if (boost_tasks[cpu] != NULL)
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return 0; /* Already created, nothing more to do. */
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/* Don't allow time recalculation while creating a new task. */
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mutex_lock(&boost_mutex);
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VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
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boost_tasks[cpu] = kthread_create(rcu_torture_boost, NULL,
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"rcu_torture_boost");
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if (IS_ERR(boost_tasks[cpu])) {
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retval = PTR_ERR(boost_tasks[cpu]);
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VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
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n_rcu_torture_boost_ktrerror++;
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boost_tasks[cpu] = NULL;
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mutex_unlock(&boost_mutex);
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return retval;
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}
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kthread_bind(boost_tasks[cpu], cpu);
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wake_up_process(boost_tasks[cpu]);
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mutex_unlock(&boost_mutex);
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return 0;
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}
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static int rcutorture_cpu_notify(struct notifier_block *self,
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unsigned long action, void *hcpu)
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{
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long cpu = (long)hcpu;
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switch (action) {
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case CPU_ONLINE:
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case CPU_DOWN_FAILED:
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(void)rcutorture_booster_init(cpu);
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break;
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case CPU_DOWN_PREPARE:
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rcutorture_booster_cleanup(cpu);
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break;
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default:
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break;
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}
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return NOTIFY_OK;
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}
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static struct notifier_block rcutorture_cpu_nb = {
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.notifier_call = rcutorture_cpu_notify,
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};
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static void
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rcu_torture_cleanup(void)
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{
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@ -1127,7 +1343,7 @@ rcu_torture_cleanup(void)
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}
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fullstop = FULLSTOP_RMMOD;
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mutex_unlock(&fullstop_mutex);
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unregister_reboot_notifier(&rcutorture_nb);
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unregister_reboot_notifier(&rcutorture_shutdown_nb);
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if (stutter_task) {
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VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
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kthread_stop(stutter_task);
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@ -1184,6 +1400,12 @@ rcu_torture_cleanup(void)
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kthread_stop(fqs_task);
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}
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fqs_task = NULL;
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if ((test_boost == 1 && cur_ops->can_boost) ||
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test_boost == 2) {
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unregister_cpu_notifier(&rcutorture_cpu_nb);
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for_each_possible_cpu(i)
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rcutorture_booster_cleanup(i);
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}
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/* Wait for all RCU callbacks to fire. */
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@ -1195,9 +1417,9 @@ rcu_torture_cleanup(void)
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if (cur_ops->cleanup)
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cur_ops->cleanup();
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if (atomic_read(&n_rcu_torture_error))
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rcu_torture_print_module_parms("End of test: FAILURE");
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rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
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else
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rcu_torture_print_module_parms("End of test: SUCCESS");
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rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
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}
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static int __init
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@ -1242,7 +1464,7 @@ rcu_torture_init(void)
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nrealreaders = nreaders;
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else
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nrealreaders = 2 * num_online_cpus();
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rcu_torture_print_module_parms("Start of test");
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rcu_torture_print_module_parms(cur_ops, "Start of test");
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fullstop = FULLSTOP_DONTSTOP;
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/* Set up the freelist. */
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@ -1263,6 +1485,12 @@ rcu_torture_init(void)
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atomic_set(&n_rcu_torture_free, 0);
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atomic_set(&n_rcu_torture_mberror, 0);
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atomic_set(&n_rcu_torture_error, 0);
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n_rcu_torture_boost_ktrerror = 0;
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n_rcu_torture_boost_rterror = 0;
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n_rcu_torture_boost_allocerror = 0;
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n_rcu_torture_boost_afferror = 0;
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n_rcu_torture_boost_failure = 0;
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n_rcu_torture_boosts = 0;
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for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
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atomic_set(&rcu_torture_wcount[i], 0);
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for_each_possible_cpu(cpu) {
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@ -1376,7 +1604,27 @@ rcu_torture_init(void)
|
|||
goto unwind;
|
||||
}
|
||||
}
|
||||
register_reboot_notifier(&rcutorture_nb);
|
||||
if (test_boost_interval < 1)
|
||||
test_boost_interval = 1;
|
||||
if (test_boost_duration < 2)
|
||||
test_boost_duration = 2;
|
||||
if ((test_boost == 1 && cur_ops->can_boost) ||
|
||||
test_boost == 2) {
|
||||
int retval;
|
||||
|
||||
boost_starttime = jiffies + test_boost_interval * HZ;
|
||||
register_cpu_notifier(&rcutorture_cpu_nb);
|
||||
for_each_possible_cpu(i) {
|
||||
if (cpu_is_offline(i))
|
||||
continue; /* Heuristic: CPU can go offline. */
|
||||
retval = rcutorture_booster_init(i);
|
||||
if (retval < 0) {
|
||||
firsterr = retval;
|
||||
goto unwind;
|
||||
}
|
||||
}
|
||||
}
|
||||
register_reboot_notifier(&rcutorture_shutdown_nb);
|
||||
mutex_unlock(&fullstop_mutex);
|
||||
return 0;
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue