diff options
| -rw-r--r-- | kernel/rcutorture.c | 96 |
1 files changed, 91 insertions, 5 deletions
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index 75174c81529..773219907dd 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -48,9 +48,11 @@ MODULE_LICENSE("GPL"); static int nreaders = -1; /* # reader threads, defaults to 4*ncpus */ -static int stat_interval = 0; /* Interval between stats, in seconds. */ +static int stat_interval; /* Interval between stats, in seconds. */ /* Defaults to "only at end of test". */ -static int verbose = 0; /* Print more debug info. */ +static int verbose; /* Print more debug info. */ +static int test_no_idle_hz; /* Test RCU's support for tickless idle CPUs. */ +static int shuffle_interval = 5; /* Interval between shuffles (in sec)*/ MODULE_PARM(nreaders, "i"); MODULE_PARM_DESC(nreaders, "Number of RCU reader threads"); @@ -58,6 +60,10 @@ MODULE_PARM(stat_interval, "i"); MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s"); MODULE_PARM(verbose, "i"); MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s"); +MODULE_PARM(test_no_idle_hz, "i"); +MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs"); +MODULE_PARM(shuffle_interval, "i"); +MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles"); #define TORTURE_FLAG "rcutorture: " #define PRINTK_STRING(s) \ do { printk(KERN_ALERT TORTURE_FLAG s "\n"); } while (0) @@ -72,6 +78,7 @@ static int nrealreaders; static struct task_struct *writer_task; static struct task_struct **reader_tasks; static struct task_struct *stats_task; +static struct task_struct *shuffler_task; #define RCU_TORTURE_PIPE_LEN 10 @@ -375,12 +382,77 @@ rcu_torture_stats(void *arg) return 0; } +static int rcu_idle_cpu; /* Force all torture tasks off this CPU */ + +/* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case + * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs. + */ +void rcu_torture_shuffle_tasks(void) +{ + cpumask_t tmp_mask = CPU_MASK_ALL; + int i; + + lock_cpu_hotplug(); + + /* No point in shuffling if there is only one online CPU (ex: UP) */ + if (num_online_cpus() == 1) { + unlock_cpu_hotplug(); + return; + } + + if (rcu_idle_cpu != -1) + cpu_clear(rcu_idle_cpu, tmp_mask); + + set_cpus_allowed(current, tmp_mask); + + if (reader_tasks != NULL) { + for (i = 0; i < nrealreaders; i++) + if (reader_tasks[i]) + set_cpus_allowed(reader_tasks[i], tmp_mask); + } + + if (writer_task) + set_cpus_allowed(writer_task, tmp_mask); + + if (stats_task) + set_cpus_allowed(stats_task, tmp_mask); + + if (rcu_idle_cpu == -1) + rcu_idle_cpu = num_online_cpus() - 1; + else + rcu_idle_cpu--; + + unlock_cpu_hotplug(); +} + +/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the + * system to become idle at a time and cut off its timer ticks. This is meant + * to test the support for such tickless idle CPU in RCU. + */ +static int +rcu_torture_shuffle(void *arg) +{ + VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started"); + do { + schedule_timeout_interruptible(shuffle_interval * HZ); + rcu_torture_shuffle_tasks(); + } while (!kthread_should_stop()); + VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping"); + return 0; +} + static void rcu_torture_cleanup(void) { int i; fullstop = 1; + if (shuffler_task != NULL) { + VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task"); + kthread_stop(shuffler_task); + } + shuffler_task = NULL; + if (writer_task != NULL) { VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task"); kthread_stop(writer_task); @@ -429,9 +501,11 @@ rcu_torture_init(void) nrealreaders = nreaders; else nrealreaders = 2 * num_online_cpus(); - printk(KERN_ALERT TORTURE_FLAG - "--- Start of test: nreaders=%d stat_interval=%d verbose=%d\n", - nrealreaders, stat_interval, verbose); + printk(KERN_ALERT TORTURE_FLAG "--- Start of test: nreaders=%d " + "stat_interval=%d verbose=%d test_no_idle_hz=%d " + "shuffle_interval = %d\n", + nrealreaders, stat_interval, verbose, test_no_idle_hz, + shuffle_interval); fullstop = 0; /* Set up the freelist. */ @@ -501,6 +575,18 @@ rcu_torture_init(void) goto unwind; } } + if (test_no_idle_hz) { + rcu_idle_cpu = num_online_cpus() - 1; + /* Create the shuffler thread */ + shuffler_task = kthread_run(rcu_torture_shuffle, NULL, + "rcu_torture_shuffle"); + if (IS_ERR(shuffler_task)) { + firsterr = PTR_ERR(shuffler_task); + VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler"); + shuffler_task = NULL; + goto unwind; + } + } return 0; unwind: |