--- /dev/null
+/* test-cmpxchg.c
+ *
+ * Test time spent in a LTTng instrumentation probe.
+ */
+
+
+#include <linux/config.h>
+#include <linux/jiffies.h>
+#include <linux/compiler.h>
+#include <linux/init.h>
+#include <linux/module.h>
+
+
+#define cmpxchg_up(ptr,o,n)\
+ ((__typeof__(*(ptr)))__cmpxchg_up((ptr),(unsigned long)(o),\
+ (unsigned long)(n),sizeof(*(ptr))))
+static inline unsigned long __cmpxchg_up(volatile void *ptr, unsigned long old,
+ unsigned long new, int size)
+{
+ unsigned long prev;
+ switch (size) {
+ case 1:
+ __asm__ __volatile__("cmpxchgb %b1,%2"
+ : "=a"(prev)
+ : "q"(new), "m"(*__xg(ptr)), "0"(old)
+ : "memory");
+ return prev;
+ case 2:
+ __asm__ __volatile__("cmpxchgw %w1,%2"
+ : "=a"(prev)
+ : "r"(new), "m"(*__xg(ptr)), "0"(old)
+ : "memory");
+ return prev;
+ case 4:
+ __asm__ __volatile__("cmpxchgl %1,%2"
+ : "=a"(prev)
+ : "r"(new), "m"(*__xg(ptr)), "0"(old)
+ : "memory");
+ return prev;
+ }
+ return old;
+}
+
+
+#define NR_LOOPS 20000
+
+volatile int test_val = 100;
+
+
+static inline void do_test(void)
+{
+ int val, ret;
+
+ val = test_val;
+
+ ret = cmpxchg_up(&test_val, val, val+1);
+}
+
+static int ltt_test_init(void)
+{
+ unsigned int i;
+ cycles_t time1, time2, time;
+ cycles_t max_time = 0, min_time = 18446744073709551615ULL; /* (2^64)-1 */
+ cycles_t tot_time = 0;
+ unsigned long flags;
+ printk(KERN_ALERT "test init\n");
+
+ local_irq_save(flags);
+ time1 = get_cycles();
+ for(i=0; i<NR_LOOPS; i++) {
+ //for(int j=0; j<10; j++) {
+ do_test();
+ //}
+ //max_time = max(max_time, time);
+ //min_time = min(min_time, time);
+ //printk("val : %d\n", test_val);
+ }
+ time2 = get_cycles();
+ local_irq_restore(flags);
+ time = time2 - time1;
+ tot_time += time;
+
+ printk(KERN_ALERT "test results : time non locked cmpxchg\n");
+ printk(KERN_ALERT "number of loops : %d\n", NR_LOOPS);
+ printk(KERN_ALERT "total time : %llu\n", tot_time);
+ //printk(KERN_ALERT "min : %llu\n", min_time);
+ //printk(KERN_ALERT "max : %llu\n", max_time);
+
+ printk(KERN_ALERT "test end\n");
+
+ return -EAGAIN; /* Fail will directly unload the module */
+}
+
+static void ltt_test_exit(void)
+{
+ printk(KERN_ALERT "test exit\n");
+}
+
+module_init(ltt_test_init)
+module_exit(ltt_test_exit)
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Test");
+