trunk/tests/kernel/test-tsc-sync.c

   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