+++ /dev/null
-/* test-cmpxchg-nolock.c
- *
- * Compare local cmpxchg with irq disable / enable.
- */
-
-
-#include <linux/jiffies.h>
-#include <linux/compiler.h>
-#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/math64.h>
-#include <asm/timex.h>
-#include <asm/system.h>
-
-#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_cycles();
- for (i = 0; i < NR_LOOPS; i++) {
- asm volatile ("");
- }
- time2 = get_cycles();
- 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", time);
- 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_sync_cmpxchg(void)
-{
- int ret;
- unsigned long flags;
- unsigned int i;
- cycles_t time1, time2, time;
- u32 rem;
-
- local_irq_save(flags);
- preempt_disable();
- time1 = get_cycles();
- for (i = 0; i < NR_LOOPS; i++) {
-#ifdef CONFIG_X86_32
- ret = sync_cmpxchg(&test_val, 0, 0);
-#else
- ret = cmpxchg(&test_val, 0, 0);
-#endif
- }
- time2 = get_cycles();
- local_irq_restore(flags);
- preempt_enable();
- time = time2 - time1;
-
- printk(KERN_ALERT "test results: time for locked cmpxchg\n");
- printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
- printk(KERN_ALERT "total time: %llu\n", time);
- time = div_u64_rem(time, NR_LOOPS, &rem);
- printk(KERN_ALERT "-> locked cmpxchg takes %llu cycles\n", time);
- printk(KERN_ALERT "test end\n");
-}
-
-static void do_test_cmpxchg(void)
-{
- int ret;
- unsigned long flags;
- unsigned int i;
- cycles_t time1, time2, time;
- u32 rem;
-
- local_irq_save(flags);
- preempt_disable();
- time1 = get_cycles();
- for (i = 0; i < NR_LOOPS; i++) {
- ret = cmpxchg_local(&test_val, 0, 0);
- }
- time2 = get_cycles();
- local_irq_restore(flags);
- preempt_enable();
- time = time2 - time1;
-
- printk(KERN_ALERT "test results: time for non locked cmpxchg\n");
- printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
- printk(KERN_ALERT "total time: %llu\n", time);
- time = div_u64_rem(time, NR_LOOPS, &rem);
- printk(KERN_ALERT "-> non locked cmpxchg takes %llu cycles\n", time);
- printk(KERN_ALERT "test end\n");
-}
-static void do_test_sync_inc(void)
-{
- int ret;
- unsigned long flags;
- unsigned int i;
- cycles_t time1, time2, time;
- u32 rem;
- atomic_t val;
-
- local_irq_save(flags);
- preempt_disable();
- time1 = get_cycles();
- for (i = 0; i < NR_LOOPS; i++) {
- ret = atomic_add_return(10, &val);
- }
- time2 = get_cycles();
- local_irq_restore(flags);
- preempt_enable();
- time = time2 - time1;
-
- printk(KERN_ALERT "test results: time for locked add return\n");
- printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
- printk(KERN_ALERT "total time: %llu\n", time);
- time = div_u64_rem(time, NR_LOOPS, &rem);
- printk(KERN_ALERT "-> locked add return takes %llu cycles\n", time);
- printk(KERN_ALERT "test end\n");
-}
-
-
-static void do_test_inc(void)
-{
- int ret;
- unsigned long flags;
- unsigned int i;
- cycles_t time1, time2, time;
- u32 rem;
- local_t loc_val;
-
- local_irq_save(flags);
- preempt_disable();
- time1 = get_cycles();
- for (i = 0; i < NR_LOOPS; i++) {
- ret = local_add_return(10, &loc_val);
- }
- time2 = get_cycles();
- local_irq_restore(flags);
- preempt_enable();
- time = time2 - time1;
-
- printk(KERN_ALERT "test results: time for non locked add return\n");
- printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
- printk(KERN_ALERT "total time: %llu\n", time);
- time = div_u64_rem(time, NR_LOOPS, &rem);
- printk(KERN_ALERT "-> non locked add return takes %llu cycles\n", time);
- printk(KERN_ALERT "test end\n");
-}
-
-
-
-/*
- * This test will have a higher standard deviation due to incoming interrupts.
- */
-static void do_test_enable_int(void)
-{
- unsigned long flags;
- unsigned int i;
- cycles_t time1, time2, time;
- u32 rem;
-
- local_irq_save(flags);
- preempt_disable();
- time1 = get_cycles();
- for (i = 0; i < NR_LOOPS; i++) {
- local_irq_restore(flags);
- }
- time2 = get_cycles();
- local_irq_restore(flags);
- preempt_enable();
- time = time2 - time1;
-
- printk(KERN_ALERT "test results: time for enabling interrupts (STI)\n");
- printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
- printk(KERN_ALERT "total time: %llu\n", time);
- time = div_u64_rem(time, NR_LOOPS, &rem);
- printk(KERN_ALERT "-> enabling interrupts (STI) takes %llu cycles\n",
- time);
- printk(KERN_ALERT "test end\n");
-}
-
-static void do_test_disable_int(void)
-{
- unsigned long flags, flags2;
- unsigned int i;
- cycles_t time1, time2, time;
- u32 rem;
-
- local_irq_save(flags);
- preempt_disable();
- time1 = get_cycles();
- for ( i = 0; i < NR_LOOPS; i++) {
- local_irq_save(flags2);
- }
- time2 = get_cycles();
- local_irq_restore(flags);
- preempt_enable();
- time = time2 - time1;
-
- printk(KERN_ALERT "test results: time for disabling interrupts (CLI)\n");
- printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
- printk(KERN_ALERT "total time: %llu\n", time);
- time = div_u64_rem(time, NR_LOOPS, &rem);
- printk(KERN_ALERT "-> disabling interrupts (CLI) takes %llu cycles\n",
- time);
- printk(KERN_ALERT "test end\n");
-}
-
-static void do_test_int(void)
-{
- unsigned long flags;
- unsigned int i;
- cycles_t time1, time2, time;
- u32 rem;
-
- local_irq_save(flags);
- preempt_disable();
- time1 = get_cycles();
- for (i = 0; i < NR_LOOPS; i++) {
- local_irq_restore(flags);
- local_irq_save(flags);
- }
- time2 = get_cycles();
- local_irq_restore(flags);
- preempt_enable();
- time = time2 - time1;
-
- printk(KERN_ALERT "test results: time for disabling/enabling interrupts (STI/CLI)\n");
- printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
- printk(KERN_ALERT "total time: %llu\n", time);
- time = div_u64_rem(time, NR_LOOPS, &rem);
- printk(KERN_ALERT "-> enabling/disabling interrupts (STI/CLI) takes %llu cycles\n",
- time);
- printk(KERN_ALERT "test end\n");
-}
-
-
-
-static int ltt_test_init(void)
-{
- printk(KERN_ALERT "test init\n");
-
- do_testbaseline();
- do_test_sync_cmpxchg();
- do_test_cmpxchg();
- do_test_sync_inc();
- do_test_inc();
- do_test_enable_int();
- do_test_disable_int();
- do_test_int();
- 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("Cmpxchg vs int Test");
-
projects / lttv.git / blobdiff