tests/kernel/test-cmpxchg.c

   1 /* test-cmpxchg.c
   2  *
   3  * Test time spent in a LTTng instrumentation probe.
   4  */
   5
   6
   7 #include <linux/init.h>
   8 #include <linux/module.h>
   9 #include <linux/ltt-core.h>
  10 #include <asm/system.h>
  11
  12 #define NR_LOOPS 2000
  13
  14 static volatile int test_val = 100;
  15
  16 static void do_test(void)
  17 {
  18         int val;
  19
  20         val = test_val;
  21
  22         ret = cmpxchg(&test_val, val, 101);
  23 }
  24
  25 static int ltt_test_init(void)
  26 {
  27         unsigned int i;
  28         cycles_t time1, time2, time;
  29         cycles_t max_time = 0, min_time = 18446744073709551615ULL; /* (2^64)-1 */
  30         cycles_t tot_time = 0;
  31         unsigned long flags;
  32         printk(KERN_ALERT "test init\n");
  33
  34         local_irq_save(flags);
  35         for(i=0; i<NR_LOOPS; i++) {
  36                 time1 = get_cycles();
  37                 do_test();
  38                 time2 = get_cycles();
  39                 time = time2 - time1;
  40                 max_time = max(max_time, time);
  41                 min_time = min(min_time, time);
  42                 tot_time += time;
  43         }
  44         local_irq_restore(flags);
  45
  46         printk(KERN_ALERT "test results : time per probe\n");
  47         printk(KERN_ALERT "number of loops : %d\n", NR_LOOPS);
  48         printk(KERN_ALERT "total time : %llu\n", tot_time);
  49         printk(KERN_ALERT "min : %llu\n", min_time);
  50         printk(KERN_ALERT "max : %llu\n", max_time);
  51
  52         printk(KERN_ALERT "test end\n");
  53
  54         return -EAGAIN; /* Fail will directly unload the module */
  55 }
  56
  57 static void ltt_test_exit(void)
  58 {
  59         printk(KERN_ALERT "test exit\n");
  60 }
  61
  62 module_init(ltt_test_init)
  63 module_exit(ltt_test_exit)
  64
  65 MODULE_LICENSE("GPL");
  66 MODULE_AUTHOR("Mathieu Desnoyers");
  67 MODULE_DESCRIPTION("Linux Trace Toolkit Test");
  68