tests/kernel/test-cmpxchg-nolock.c

   1 /* test-cmpxchg.c
   2  *
   3  * Test time spent in a LTTng instrumentation probe.
   4  */
   5
   6
   7 #include <linux/jiffies.h>
   8 #include <linux/compiler.h>
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11
  12 #if 0
  13 #define cmpxchg_up(ptr,o,n)\
  14         ((__typeof__(*(ptr)))__cmpxchg_up((ptr),(unsigned long)(o),\
  15                                         (unsigned long)(n),sizeof(*(ptr))))
  16 static inline unsigned long __cmpxchg_up(volatile void *ptr, unsigned long old,
  17                                       unsigned long new, int size)
  18 {
  19         unsigned long prev;
  20         switch (size) {
  21         case 1:
  22                 __asm__ __volatile__("cmpxchgb %b1,%2"
  23                                      : "=a"(prev)
  24                                      : "q"(new), "m"(*__xg(ptr)), "0"(old)
  25                                      : "memory");
  26                 return prev;
  27         case 2:
  28                 __asm__ __volatile__("cmpxchgw %w1,%2"
  29                                      : "=a"(prev)
  30                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
  31                                      : "memory");
  32                 return prev;
  33         case 4:
  34                 __asm__ __volatile__("cmpxchgl %1,%2"
  35                                      : "=a"(prev)
  36                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
  37                                      : "memory");
  38                 return prev;
  39         }
  40         return old;
  41 }
  42 #endif //0
  43
  44 #define NR_LOOPS 20000
  45
  46 volatile int test_val = 100;
  47
  48
  49 static inline void do_test(void)
  50 {
  51         int val, ret;
  52
  53         val = test_val;
  54
  55         ret = cmpxchg_up(&test_val, val, val+1);
  56 }
  57
  58 static int ltt_test_init(void)
  59 {
  60         unsigned int i;
  61         cycles_t time1, time2, time;
  62         cycles_t max_time = 0, min_time = 18446744073709551615ULL; /* (2^64)-1 */
  63         cycles_t tot_time = 0;
  64         unsigned long flags;
  65         printk(KERN_ALERT "test init\n");
  66
  67         local_irq_save(flags);
  68         time1 = get_cycles();
  69         for(i=0; i<NR_LOOPS; i++) {
  70                 //for(int j=0; j<10; j++) {
  71                 do_test();
  72                 //}
  73                 //max_time = max(max_time, time);
  74                 //min_time = min(min_time, time);
  75                 //printk("val : %d\n", test_val);
  76         }
  77         time2 = get_cycles();
  78         local_irq_restore(flags);
  79         time = time2 - time1;
  80         tot_time += time;
  81
  82         printk(KERN_ALERT "test results : time non locked cmpxchg\n");
  83         printk(KERN_ALERT "number of loops : %d\n", NR_LOOPS);
  84         printk(KERN_ALERT "total time : %llu\n", tot_time);
  85         //printk(KERN_ALERT "min : %llu\n", min_time);
  86         //printk(KERN_ALERT "max : %llu\n", max_time);
  87
  88         printk(KERN_ALERT "test end\n");
  89
  90         return -EAGAIN; /* Fail will directly unload the module */
  91 }
  92
  93 static void ltt_test_exit(void)
  94 {
  95         printk(KERN_ALERT "test exit\n");
  96 }
  97
  98 module_init(ltt_test_init)
  99 module_exit(ltt_test_exit)
 100
 101 MODULE_LICENSE("GPL");
 102 MODULE_AUTHOR("Mathieu Desnoyers");
 103 MODULE_DESCRIPTION("Linux Trace Toolkit Test");
 104