| 1 | /* test-tsc-sync.c |
| 2 | * |
| 3 | * Test TSC sync |
| 4 | */ |
| 5 | |
| 6 | |
| 7 | #include <linux/module.h> |
| 8 | #include <linux/timer.h> |
| 9 | #include <asm/timex.h> |
| 10 | #include <linux/jiffies.h> |
| 11 | |
| 12 | static DEFINE_PER_CPU(cycles_t, count) = 0; |
| 13 | |
| 14 | static struct timer_list test_timer; |
| 15 | |
| 16 | static atomic_t kernel_threads_to_run; |
| 17 | |
| 18 | |
| 19 | /* IPI called on each CPU. */ |
| 20 | static void test_each(void *info) |
| 21 | { |
| 22 | unsigned long flags; |
| 23 | local_irq_save(flags); |
| 24 | atomic_dec(&kernel_threads_to_run); |
| 25 | while(atomic_read(&kernel_threads_to_run)) |
| 26 | cpu_relax(); |
| 27 | __get_cpu_var(count) = get_cycles_sync(); |
| 28 | local_irq_restore(flags); |
| 29 | } |
| 30 | |
| 31 | static void do_test_timer(unsigned long data) |
| 32 | { |
| 33 | int cpu; |
| 34 | |
| 35 | atomic_set(&kernel_threads_to_run, num_online_cpus()); |
| 36 | |
| 37 | smp_call_function(test_each, NULL, 0, 0); |
| 38 | test_each(NULL); |
| 39 | /* Read all the counters */ |
| 40 | printk("Counters read from CPU %d\n", smp_processor_id()); |
| 41 | for_each_online_cpu(cpu) { |
| 42 | printk("Read : CPU %d, count %llu\n", cpu, |
| 43 | per_cpu(count, cpu)); |
| 44 | } |
| 45 | del_timer(&test_timer); |
| 46 | test_timer.expires = jiffies + 1000; |
| 47 | add_timer(&test_timer); |
| 48 | } |
| 49 | |
| 50 | static int __init test_init(void) |
| 51 | { |
| 52 | /* initialize the timer that will increment the counter */ |
| 53 | init_timer(&test_timer); |
| 54 | test_timer.function = do_test_timer; |
| 55 | test_timer.expires = jiffies + 1; |
| 56 | add_timer(&test_timer); |
| 57 | |
| 58 | return 0; |
| 59 | } |
| 60 | |
| 61 | static void __exit test_exit(void) |
| 62 | { |
| 63 | del_timer_sync(&test_timer); |
| 64 | } |
| 65 | |
| 66 | module_init(test_init); |
| 67 | module_exit(test_exit); |
| 68 | |
| 69 | MODULE_LICENSE("GPL"); |
| 70 | MODULE_AUTHOR("Mathieu Desnoyers"); |
| 71 | MODULE_DESCRIPTION("sync tsc test"); |
| 72 | |