arch/mips/kernel/spinlock_test.c

   1 #include <linux/init.h>
   2 #include <linux/kthread.h>
   3 #include <linux/hrtimer.h>
   4 #include <linux/fs.h>
   5 #include <linux/debugfs.h>
   6 #include <linux/export.h>
   7 #include <linux/spinlock.h>
   8
   9
  10 static int ss_get(void *data, u64 *val)
  11 {
  12         ktime_t start, finish;
  13         int loops;
  14         int cont;
  15         DEFINE_RAW_SPINLOCK(ss_spin);
  16
  17         loops = 1000000;
  18         cont = 1;
  19
  20         start = ktime_get();
  21
  22         while (cont) {
  23                 raw_spin_lock(&ss_spin);
  24                 loops--;
  25                 if (loops == 0)
  26                         cont = 0;
  27                 raw_spin_unlock(&ss_spin);
  28         }
  29
  30         finish = ktime_get();
  31
  32         *val = ktime_us_delta(finish, start);
  33
  34         return 0;
  35 }
  36
  37 DEFINE_SIMPLE_ATTRIBUTE(fops_ss, ss_get, NULL, "%llu\n");
  38
  39
  40
  41 struct spin_multi_state {
  42         raw_spinlock_t lock;
  43         atomic_t start_wait;
  44         atomic_t enter_wait;
  45         atomic_t exit_wait;
  46         int loops;
  47 };
  48
  49 struct spin_multi_per_thread {
  50         struct spin_multi_state *state;
  51         ktime_t start;
  52 };
  53
  54 static int multi_other(void *data)
  55 {
  56         int loops;
  57         int cont;
  58         struct spin_multi_per_thread *pt = data;
  59         struct spin_multi_state *s = pt->state;
  60
  61         loops = s->loops;
  62         cont = 1;
  63
  64         atomic_dec(&s->enter_wait);
  65
  66         while (atomic_read(&s->enter_wait))
  67                 ; /* spin */
  68
  69         pt->start = ktime_get();
  70
  71         atomic_dec(&s->start_wait);
  72
  73         while (atomic_read(&s->start_wait))
  74                 ; /* spin */
  75
  76         while (cont) {
  77                 raw_spin_lock(&s->lock);
  78                 loops--;
  79                 if (loops == 0)
  80                         cont = 0;
  81                 raw_spin_unlock(&s->lock);
  82         }
  83
  84         atomic_dec(&s->exit_wait);
  85         while (atomic_read(&s->exit_wait))
  86                 ; /* spin */
  87         return 0;
  88 }
  89
  90 static int multi_get(void *data, u64 *val)
  91 {
  92         ktime_t finish;
  93         struct spin_multi_state ms;
  94         struct spin_multi_per_thread t1, t2;
  95
  96         ms.lock = __RAW_SPIN_LOCK_UNLOCKED("multi_get");
  97         ms.loops = 1000000;
  98
  99         atomic_set(&ms.start_wait, 2);
 100         atomic_set(&ms.enter_wait, 2);
 101         atomic_set(&ms.exit_wait, 2);
 102         t1.state = &ms;
 103         t2.state = &ms;
 104
 105         kthread_run(multi_other, &t2, "multi_get");
 106
 107         multi_other(&t1);
 108
 109         finish = ktime_get();
 110
 111         *val = ktime_us_delta(finish, t1.start);
 112
 113         return 0;
 114 }
 115
 116 DEFINE_SIMPLE_ATTRIBUTE(fops_multi, multi_get, NULL, "%llu\n");
 117
 118
 119 extern struct dentry *mips_debugfs_dir;
 120 static int __init spinlock_test(void)
 121 {
 122         struct dentry *d;
 123
 124         if (!mips_debugfs_dir)
 125                 return -ENODEV;
 126
 127         d = debugfs_create_file("spin_single", S_IRUGO,
 128                                 mips_debugfs_dir, NULL,
 129                                 &fops_ss);
 130         if (!d)
 131                 return -ENOMEM;
 132
 133         d = debugfs_create_file("spin_multi", S_IRUGO,
 134                                 mips_debugfs_dir, NULL,
 135                                 &fops_multi);
 136         if (!d)
 137                 return -ENOMEM;
 138
 139         return 0;
 140 }
 141 device_initcall(spinlock_test);