-/* test-cmpxchg-nolock.c
+/* test-rcu-speed.c
*
- * Compare local cmpxchg with irq disable / enable.
+ * Compare speed of :
+ * - spin lock irqsave/ spin unlock irqrestore
+ * - using a sequence read lock (uncontended)
+ * - preempt disable/enable
*/
#include <linux/compiler.h>
#include <linux/init.h>
#include <linux/module.h>
-#include <linux/calc64.h>
+#include <linux/math64.h>
#include <linux/spinlock.h>
#include <linux/seqlock.h>
+#include <linux/cpumask.h>
#include <asm/timex.h>
#include <asm/system.h>
#define NR_LOOPS 20000
+#ifndef CONFIG_PREEMPT
+#error "Your kernel should be build with preemption enabled"
+#endif
+
+#ifdef CONFIG_DEBUG_PREEMPT
+#error "Please disable CONFIG_DEBUG_PREEMPT"
+#endif
+
+#ifdef CONFIG_DEBUG_SPINLOCK
+#error "Please disable CONFIG_DEBUG_SPINLOCK"
+#endif
+
+#ifdef CONFIG_LOCKDEP
+#error "Please disable CONFIG_LOCKDEP"
+#endif
+
int test_val;
static void do_testbaseline(void)
{
- long flags;
+ unsigned long flags;
unsigned int i;
cycles_t time1, time2, time;
- long rem;
+ u32 rem;
local_irq_save(flags);
preempt_disable();
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", time);
- time = div_long_long_rem(time, NR_LOOPS, &rem);
+ time = div_u64_rem(time, NR_LOOPS, &rem);
printk(KERN_ALERT "-> baseline takes %llu cycles\n", time);
printk(KERN_ALERT "test end\n");
}
static void do_test_spinlock(void)
{
static DEFINE_SPINLOCK(mylock);
- long flags;
+ unsigned long flags;
unsigned int i;
cycles_t time1, time2, time;
- long rem;
+ u32 rem;
preempt_disable();
spin_lock_irqsave(&mylock, flags);
printk(KERN_ALERT "test results: time for spinlock\n");
printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
printk(KERN_ALERT "total time: %llu\n", time);
- time = div_long_long_rem(time, NR_LOOPS, &rem);
+ time = div_u64_rem(time, NR_LOOPS, &rem);
printk(KERN_ALERT "-> spinlock takes %llu cycles\n", time);
printk(KERN_ALERT "test end\n");
}
{
static seqlock_t test_lock;
unsigned long seq;
- long flags;
+ unsigned long flags;
unsigned int i;
cycles_t time1, time2, time;
- long rem;
+ u32 rem;
local_irq_save(flags);
- preempt_disable();
time1 = get_cycles();
for (i = 0; i < NR_LOOPS; i++) {
do {
} while (read_seqretry(&test_lock, seq));
}
time2 = get_cycles();
- preempt_enable();
time = time2 - time1;
local_irq_restore(flags);
printk(KERN_ALERT "test results: time for seqlock\n");
printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
printk(KERN_ALERT "total time: %llu\n", time);
- time = div_long_long_rem(time, NR_LOOPS, &rem);
+ time = div_u64_rem(time, NR_LOOPS, &rem);
printk(KERN_ALERT "-> seqlock takes %llu cycles\n", time);
printk(KERN_ALERT "test end\n");
}
/*
- * This test will have a higher standard deviation due to incoming interrupts.
+ * Note : This test _should_ trigger lockdep errors due to preemption
+ * disabling/enabling within irq off section. Given we are only interested in
+ * having the most precise measurement for preemption disable/enable, we don't
+ * care about this.
*/
static void do_test_preempt(void)
{
- long flags;
+ unsigned long flags;
unsigned int i;
cycles_t time1, time2, time;
- long rem;
+ u32 rem;
local_irq_save(flags);
preempt_disable();
printk(KERN_ALERT "test results: time for preempt disable/enable pairs\n");
printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
printk(KERN_ALERT "total time: %llu\n", time);
- time = div_long_long_rem(time, NR_LOOPS, &rem);
+ time = div_u64_rem(time, NR_LOOPS, &rem);
printk(KERN_ALERT "-> preempt disable/enable pair takes %llu cycles\n",
time);
printk(KERN_ALERT "test end\n");
{
printk(KERN_ALERT "test init\n");
+ printk(KERN_ALERT "Number of active CPUs : %d\n", num_online_cpus());
do_testbaseline();
do_test_spinlock();
do_test_seqlock();