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/config.h>
   8 #include <linux/jiffies.h>
   9 #include <linux/compiler.h>
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12
  13 #define NR_LOOPS 2000
  14
  15 volatile int test_val = 100;
  16
  17
  18 static void do_test(void)
  19 {
  20         int val, ret;
  21
  22         val = test_val;
  23
  24         ret = cmpxchg(&test_val, val, val+1);
  25 }
  26
  27 void (*fct)(void) = do_test;
  28
  29 static int ltt_test_init(void)
  30 {
  31         unsigned int i;
  32         cycles_t time1, time2, time;
  33         cycles_t max_time = 0, min_time = 18446744073709551615ULL; /* (2^64)-1 */
  34         cycles_t tot_time = 0;
  35         unsigned long flags;
  36         printk(KERN_ALERT "test init\n");
  37
  38         local_irq_save(flags);
  39         time1 = get_cycles();
  40         for(i=0; i<NR_LOOPS; i++) {
  41                 //for(int j=0; j<10; j++) {
  42                 do_test();
  43                 //}
  44                 //max_time = max(max_time, time);
  45                 //min_time = min(min_time, time);
  46                 //printk("val : %d\n", test_val);
  47         }
  48         time2 = get_cycles();
  49         local_irq_restore(flags);
  50         time = time2 - time1;
  51         tot_time += time;
  52
  53         printk(KERN_ALERT "test results : time per probe\n");
  54         printk(KERN_ALERT "number of loops : %d\n", NR_LOOPS);
  55         printk(KERN_ALERT "total time : %llu\n", tot_time);
  56         //printk(KERN_ALERT "min : %llu\n", min_time);
  57         //printk(KERN_ALERT "max : %llu\n", max_time);
  58
  59         printk(KERN_ALERT "test end\n");
  60
  61         return -EAGAIN; /* Fail will directly unload the module */
  62 }
  63
  64 static void ltt_test_exit(void)
  65 {
  66         printk(KERN_ALERT "test exit\n");
  67 }
  68
  69 module_init(ltt_test_init)
  70 module_exit(ltt_test_exit)
  71
  72 MODULE_LICENSE("GPL");
  73 MODULE_AUTHOR("Mathieu Desnoyers");
  74 MODULE_DESCRIPTION("Linux Trace Toolkit Test");
  75