tests/kernel/test-time-probe.c

   1 /* test-time-probe.c
   2  *
   3  * Test time spent in a LTTng instrumentation probe.
   4  */
   5
   6
   7 #include "ltt-facility-tests.h"
   8
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11 #include <linux/ltt-core.h>
  12
  13 /* Event logged : 4 bytes + 20 bytes header = 24 bytes. Let's use 1MB of
  14  * buffers. 1MB / 24bytes = 43690. So, if we write 20000 event, we should not
  15  * lose events. Check event lost count after tests. */
  16
  17 #define NR_LOOPS 20000
  18
  19 static int ltt_test_init(void)
  20 {
  21         unsigned int i;
  22         cycles_t time1, time2, time;
  23         cycles_t max_time = 0, min_time = 18446744073709551615ULL; /* (2^64)-1 */
  24         cycles_t tot_time = 0;
  25         unsigned long flags;
  26         printk(KERN_ALERT "test init\n");
  27
  28         local_irq_save(flags);
  29         for(i=0; i<NR_LOOPS; i++) {
  30                 time1 = get_cycles();
  31                 trace_tests_write_4bytes(5000);
  32                 time2 = get_cycles();
  33                 time = time2 - time1;
  34                 max_time = max(max_time, time);
  35                 min_time = min(min_time, time);
  36                 tot_time += time;
  37         }
  38         local_irq_restore(flags);
  39
  40         printk(KERN_ALERT "test results : time per probe\n");
  41         printk(KERN_ALERT "number of loops : %d\n", NR_LOOPS);
  42         printk(KERN_ALERT "total time : %llu\n", tot_time);
  43         printk(KERN_ALERT "min : %llu\n", min_time);
  44         printk(KERN_ALERT "max : %llu\n", max_time);
  45
  46         printk(KERN_ALERT "test end\n");
  47
  48         return -EAGAIN; /* Fail will directly unload the module */
  49 }
  50
  51 static void ltt_test_exit(void)
  52 {
  53         printk(KERN_ALERT "test exit\n");
  54 }
  55
  56 module_init(ltt_test_init)
  57 module_exit(ltt_test_exit)
  58
  59 MODULE_LICENSE("GPL");
  60 MODULE_AUTHOR("Mathieu Desnoyers");
  61 MODULE_DESCRIPTION("Linux Trace Toolkit Test");
  62