Print bringup timing

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 1a46eb57d8f71de6b0030e74bf0a6d4bed67d1f4..9979f670501b0a0f1b06d65c40996a68e53c272c 100644 (file)
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1463,6 +1463,7 @@ void bringup_nonboot_cpus(unsigned int setup_max_cpus)
 {
        unsigned int cpu;
        int n = setup_max_cpus - num_online_cpus();
+       cycles_t t1, t2;
 
        /* ∀ parallel pre-bringup state, bring N CPUs to it */
        if (n > 0) {
@@ -1471,22 +1472,29 @@ void bringup_nonboot_cpus(unsigned int setup_max_cpus)
                while (st <= CPUHP_BP_PARALLEL_DYN_END &&
                       cpuhp_hp_states[st].name) {
                        int i = n;
-
+                       t1 = get_cycles();
                        for_each_present_cpu(cpu) {
                                cpu_up(cpu, st);
                                if (!--i)
                                        break;
                        }
+                       t2 = get_cycles();
+
+                       printk("Brought %d CPUs to %s in %lld cycles\n", n - i,
+                              cpuhp_hp_states[st].name, t2 - t1);
                        st++;
                }
        }
 
+       t1 = get_cycles();
        for_each_present_cpu(cpu) {
                if (num_online_cpus() >= setup_max_cpus)
                        break;
                if (!cpu_online(cpu))
                        cpu_up(cpu, CPUHP_ONLINE);
        }
+       t2 = get_cycles();
+       printk("Brought CPUs online in %lld cycles\n", t2 - t1);
 }
 
 #ifdef CONFIG_PM_SLEEP_SMP