tests/kernel/test-ipi.c

   1 /*
   2  * test-ipi.c
   3  *
   4  * Copyright 2009 - Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
   5  * Distributed under GPLv2
   6  */
   7
   8 #include <linux/jiffies.h>
   9 #include <linux/compiler.h>
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/math64.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/seqlock.h>
  15 #include <linux/cpumask.h>
  16 #include <linux/smp.h>
  17 #include <asm/timex.h>
  18 #include <asm/system.h>
  19
  20 #ifdef CONFIG_ARM
  21 #include <linux/trace-clock.h>
  22 #define get_timestamp   trace_clock_read64
  23 #else
  24 #define get_timestamp   get_cycles
  25 #endif
  26
  27 #define NR_LOOPS 20000
  28
  29 int test_val;
  30
  31 static void do_testbaseline(void)
  32 {
  33         unsigned long flags;
  34         unsigned int i;
  35         cycles_t time1, time2, time;
  36         u32 rem;
  37
  38         local_irq_save(flags);
  39         preempt_disable();
  40         time1 = get_timestamp();
  41         for (i = 0; i < NR_LOOPS; i++) {
  42                 asm volatile ("");
  43         }
  44         time2 = get_timestamp();
  45         local_irq_restore(flags);
  46         preempt_enable();
  47         time = time2 - time1;
  48
  49         printk(KERN_ALERT "test results: time for baseline\n");
  50         printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
  51         printk(KERN_ALERT "total time: %llu\n", (unsigned long long)time);
  52         time = div_u64_rem(time, NR_LOOPS, &rem);
  53         printk(KERN_ALERT "-> baseline takes %llu cycles\n", (unsigned long long)time);
  54         printk(KERN_ALERT "test end\n");
  55 }
  56
  57 static void remote_wmb(void *info)
  58 {
  59         smp_wmb();
  60 }
  61
  62 static void do_test_ipi(void)
  63 {
  64         unsigned int i;
  65         int cpu;
  66         cycles_t time1, time2, time;
  67         u32 rem;
  68
  69         preempt_disable();
  70         cpu = smp_processor_id();
  71         if (cpu == 0)
  72                 cpu = 1;
  73         else
  74                 cpu = 0;
  75         time1 = get_timestamp();
  76         for (i = 0; i < NR_LOOPS; i++) {
  77                 smp_call_function_single(cpu, remote_wmb, NULL, 1);
  78         }
  79         time2 = get_timestamp();
  80         preempt_enable();
  81         time = time2 - time1;
  82
  83         printk(KERN_ALERT "test results: time for ipi\n");
  84         printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
  85         printk(KERN_ALERT "total time: %llu\n", (unsigned long long)time);
  86         time = div_u64_rem(time, NR_LOOPS, &rem);
  87         printk(KERN_ALERT "-> ipi takes %llu cycles\n", (unsigned long long)time);
  88         printk(KERN_ALERT "test end\n");
  89 }
  90
  91 static void do_test_wmb(void)
  92 {
  93         unsigned int i;
  94         cycles_t time1, time2, time;
  95         u32 rem;
  96
  97         preempt_disable();
  98         time1 = get_timestamp();
  99         for (i = 0; i < NR_LOOPS; i++) {
 100                 wmb();
 101         }
 102         time2 = get_timestamp();
 103         preempt_enable();
 104         time = time2 - time1;
 105
 106         printk(KERN_ALERT "test results: time for ipi\n");
 107         printk(KERN_ALERT "number of loops: %d\n", NR_LOOPS);
 108         printk(KERN_ALERT "total time: %llu\n", (unsigned long long)time);
 109         time = div_u64_rem(time, NR_LOOPS, &rem);
 110         printk(KERN_ALERT "-> ipi takes %llu cycles\n", (unsigned long long)time);
 111         printk(KERN_ALERT "test end\n");
 112 }
 113
 114 static int ltt_test_init(void)
 115 {
 116         printk(KERN_ALERT "test init\n");
 117
 118         printk(KERN_ALERT "Number of active CPUs : %d\n", num_online_cpus());
 119         do_testbaseline();
 120         do_test_ipi();
 121         do_test_wmb();
 122         return -EAGAIN; /* Fail will directly unload the module */
 123 }
 124
 125 static void ltt_test_exit(void)
 126 {
 127         printk(KERN_ALERT "test exit\n");
 128 }
 129
 130 module_init(ltt_test_init)
 131 module_exit(ltt_test_exit)
 132
 133 MODULE_LICENSE("GPL");
 134 MODULE_AUTHOR("Mathieu Desnoyers");
 135 MODULE_DESCRIPTION("Test read lock speed");