projects / linux-2.6 / blame
| Commit | Line | Data |
|---|---|---|
| 3cbc5640 RT |
1 | /* |
| 2 | * Fast batching percpu counters. | |
| 3 | */ | |
| 4 | ||
| 5 | #include <linux/percpu_counter.h> | |
| c67ad917 AM |
6 | #include <linux/notifier.h> |
| 7 | #include <linux/mutex.h> | |
| 8 | #include <linux/init.h> | |
| 9 | #include <linux/cpu.h> | |
| 3cbc5640 RT |
10 | #include <linux/module.h> |
| 11 | ||
| c67ad917 AM |
12 | #ifdef CONFIG_HOTPLUG_CPU |
| 13 | static LIST_HEAD(percpu_counters); | |
| 14 | static DEFINE_MUTEX(percpu_counters_lock); | |
| 15 | #endif | |
| 16 | ||
| 0216bfcf | 17 | void percpu_counter_mod(struct percpu_counter *fbc, s32 amount) |
| 3cbc5640 RT |
18 | { |
| 19 | long count; | |
| 0216bfcf | 20 | s32 *pcount; |
| 3cbc5640 RT |
21 | int cpu = get_cpu(); |
| 22 | ||
| 23 | pcount = per_cpu_ptr(fbc->counters, cpu); | |
| 24 | count = *pcount + amount; | |
| 25 | if (count >= FBC_BATCH || count <= -FBC_BATCH) { | |
| 26 | spin_lock(&fbc->lock); | |
| 27 | fbc->count += count; | |
| 28 | *pcount = 0; | |
| 29 | spin_unlock(&fbc->lock); | |
| 30 | } else { | |
| 31 | *pcount = count; | |
| 32 | } | |
| 33 | put_cpu(); | |
| 34 | } | |
| 35 | EXPORT_SYMBOL(percpu_counter_mod); | |
| 36 | ||
| 37 | /* | |
| 38 | * Add up all the per-cpu counts, return the result. This is a more accurate | |
| 39 | * but much slower version of percpu_counter_read_positive() | |
| 40 | */ | |
| 0216bfcf | 41 | s64 percpu_counter_sum(struct percpu_counter *fbc) |
| 3cbc5640 | 42 | { |
| 0216bfcf | 43 | s64 ret; |
| 3cbc5640 RT |
44 | int cpu; |
| 45 | ||
| 46 | spin_lock(&fbc->lock); | |
| 47 | ret = fbc->count; | |
| b4ef0296 | 48 | for_each_online_cpu(cpu) { |
| 0216bfcf | 49 | s32 *pcount = per_cpu_ptr(fbc->counters, cpu); |
| 3cbc5640 RT |
50 | ret += *pcount; |
| 51 | } | |
| 52 | spin_unlock(&fbc->lock); | |
| 53 | return ret < 0 ? 0 : ret; | |
| 54 | } | |
| 55 | EXPORT_SYMBOL(percpu_counter_sum); | |
| c67ad917 AM |
56 | |
| 57 | void percpu_counter_init(struct percpu_counter *fbc, s64 amount) | |
| 58 | { | |
| 59 | spin_lock_init(&fbc->lock); | |
| 60 | fbc->count = amount; | |
| 61 | fbc->counters = alloc_percpu(s32); | |
| 62 | #ifdef CONFIG_HOTPLUG_CPU | |
| 63 | mutex_lock(&percpu_counters_lock); | |
| 64 | list_add(&fbc->list, &percpu_counters); | |
| 65 | mutex_unlock(&percpu_counters_lock); | |
| 66 | #endif | |
| 67 | } | |
| 68 | EXPORT_SYMBOL(percpu_counter_init); | |
| 69 | ||
| 70 | void percpu_counter_destroy(struct percpu_counter *fbc) | |
| 71 | { | |
| 72 | free_percpu(fbc->counters); | |
| 73 | #ifdef CONFIG_HOTPLUG_CPU | |
| 74 | mutex_lock(&percpu_counters_lock); | |
| 75 | list_del(&fbc->list); | |
| 76 | mutex_unlock(&percpu_counters_lock); | |
| 77 | #endif | |
| 78 | } | |
| 79 | EXPORT_SYMBOL(percpu_counter_destroy); | |
| 80 | ||
| 81 | #ifdef CONFIG_HOTPLUG_CPU | |
| 82 | static int __cpuinit percpu_counter_hotcpu_callback(struct notifier_block *nb, | |
| 83 | unsigned long action, void *hcpu) | |
| 84 | { | |
| 85 | unsigned int cpu; | |
| 86 | struct percpu_counter *fbc; | |
| 87 | ||
| 88 | if (action != CPU_DEAD) | |
| 89 | return NOTIFY_OK; | |
| 90 | ||
| 91 | cpu = (unsigned long)hcpu; | |
| 92 | mutex_lock(&percpu_counters_lock); | |
| 93 | list_for_each_entry(fbc, &percpu_counters, list) { | |
| 94 | s32 *pcount; | |
| 95 | ||
| 96 | spin_lock(&fbc->lock); | |
| 97 | pcount = per_cpu_ptr(fbc->counters, cpu); | |
| 98 | fbc->count += *pcount; | |
| 99 | *pcount = 0; | |
| 100 | spin_unlock(&fbc->lock); | |
| 101 | } | |
| 102 | mutex_unlock(&percpu_counters_lock); | |
| 103 | return NOTIFY_OK; | |
| 104 | } | |
| 105 | ||
| 106 | static int __init percpu_counter_startup(void) | |
| 107 | { | |
| 108 | hotcpu_notifier(percpu_counter_hotcpu_callback, 0); | |
| 109 | return 0; | |
| 110 | } | |
| 111 | module_init(percpu_counter_startup); | |
| 112 | #endif |