--- /dev/null
+/*
+ * test-ipi.c
+ *
+ * Copyright 2009 - Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ * Distributed under GPLv2
+ */
+
+#include <linux/jiffies.h>
+#include <linux/compiler.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/math64.h>
+#include <linux/spinlock.h>
+#include <linux/seqlock.h>
+#include <linux/cpumask.h>
+#include <linux/smp.h>
+#include <asm/timex.h>
+#include <asm/system.h>
+
+#ifdef CONFIG_ARM
+#include <linux/trace-clock.h>
+#define get_timestamp trace_clock_read64
+#else
+#define get_timestamp get_cycles
+#endif
+
+#define NR_LOOPS 20000
+
+int test_val;
+
+static void do_testbaseline(void)
+{
+ unsigned long flags;
+ unsigned int i;
+ cycles_t time1, time2, time;
+ u32 rem;
+
+ local_irq_save(flags);
+ preempt_disable();
+ time1 = get_timestamp();
+ for (i = 0; i < NR_LOOPS; i++) {
+ asm volatile ("");
+ }
+ time2 = get_timestamp();
+ local_irq_restore(flags);
+ preempt_enable();
+ time = time2 - time1;
+
+ printk(KERN_ALERT "test results: time for baseline\n");
+ printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
+ printk(KERN_ALERT "total time: %llu\n", (unsigned long long)time);
+ time = div_u64_rem(time, NR_LOOPS, &rem);
+ printk(KERN_ALERT "-> baseline takes %llu cycles\n", (unsigned long long)time);
+ printk(KERN_ALERT "test end\n");
+}
+
+static void remote_wmb(void *info)
+{
+ smp_wmb();
+}
+
+static void do_test_ipi(void)
+{
+ unsigned int i;
+ int cpu;
+ cycles_t time1, time2, time;
+ u32 rem;
+
+ preempt_disable();
+ cpu = smp_processor_id();
+ if (cpu == 0)
+ cpu = 1;
+ else
+ cpu = 0;
+ time1 = get_timestamp();
+ for (i = 0; i < NR_LOOPS; i++) {
+ smp_call_function_single(cpu, remote_wmb, NULL, 1);
+ }
+ time2 = get_timestamp();
+ preempt_enable();
+ time = time2 - time1;
+
+ printk(KERN_ALERT "test results: time for ipi\n");
+ printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
+ printk(KERN_ALERT "total time: %llu\n", (unsigned long long)time);
+ time = div_u64_rem(time, NR_LOOPS, &rem);
+ printk(KERN_ALERT "-> ipi takes %llu cycles\n", (unsigned long long)time);
+ printk(KERN_ALERT "test end\n");
+}
+
+static void do_test_wmb(void)
+{
+ unsigned int i;
+ cycles_t time1, time2, time;
+ u32 rem;
+
+ preempt_disable();
+ time1 = get_timestamp();
+ for (i = 0; i < NR_LOOPS; i++) {
+ wmb();
+ }
+ time2 = get_timestamp();
+ preempt_enable();
+ time = time2 - time1;
+
+ printk(KERN_ALERT "test results: time for ipi\n");
+ printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
+ printk(KERN_ALERT "total time: %llu\n", (unsigned long long)time);
+ time = div_u64_rem(time, NR_LOOPS, &rem);
+ printk(KERN_ALERT "-> ipi takes %llu cycles\n", (unsigned long long)time);
+ printk(KERN_ALERT "test end\n");
+}
+
+static int ltt_test_init(void)
+{
+ printk(KERN_ALERT "test init\n");
+
+ printk(KERN_ALERT "Number of active CPUs : %d\n", num_online_cpus());
+ do_testbaseline();
+ do_test_ipi();
+ do_test_wmb();
+ 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("Test read lock speed");