Ravikiran G Thirumalai | 3cbc564 | 2006-06-23 02:05:40 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Fast batching percpu counters. |
| 3 | */ |
| 4 | |
| 5 | #include <linux/percpu_counter.h> |
Andrew Morton | c67ad91 | 2007-07-15 23:39:51 -0700 | [diff] [blame] | 6 | #include <linux/notifier.h> |
| 7 | #include <linux/mutex.h> |
| 8 | #include <linux/init.h> |
| 9 | #include <linux/cpu.h> |
Ravikiran G Thirumalai | 3cbc564 | 2006-06-23 02:05:40 -0700 | [diff] [blame] | 10 | #include <linux/module.h> |
| 11 | |
Andrew Morton | c67ad91 | 2007-07-15 23:39:51 -0700 | [diff] [blame] | 12 | #ifdef CONFIG_HOTPLUG_CPU |
| 13 | static LIST_HEAD(percpu_counters); |
| 14 | static DEFINE_MUTEX(percpu_counters_lock); |
| 15 | #endif |
| 16 | |
Peter Zijlstra | 20e8976 | 2007-10-16 23:25:43 -0700 | [diff] [blame^] | 17 | void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch) |
Ravikiran G Thirumalai | 3cbc564 | 2006-06-23 02:05:40 -0700 | [diff] [blame] | 18 | { |
Peter Zijlstra | 20e8976 | 2007-10-16 23:25:43 -0700 | [diff] [blame^] | 19 | s64 count; |
Mingming Cao | 0216bfc | 2006-06-23 02:05:41 -0700 | [diff] [blame] | 20 | s32 *pcount; |
Ravikiran G Thirumalai | 3cbc564 | 2006-06-23 02:05:40 -0700 | [diff] [blame] | 21 | int cpu = get_cpu(); |
| 22 | |
| 23 | pcount = per_cpu_ptr(fbc->counters, cpu); |
| 24 | count = *pcount + amount; |
Peter Zijlstra | 252e0ba | 2007-10-16 23:25:43 -0700 | [diff] [blame] | 25 | if (count >= batch || count <= -batch) { |
Ravikiran G Thirumalai | 3cbc564 | 2006-06-23 02:05:40 -0700 | [diff] [blame] | 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 | } |
Peter Zijlstra | 252e0ba | 2007-10-16 23:25:43 -0700 | [diff] [blame] | 35 | EXPORT_SYMBOL(__percpu_counter_add); |
Ravikiran G Thirumalai | 3cbc564 | 2006-06-23 02:05:40 -0700 | [diff] [blame] | 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 | */ |
Mingming Cao | 0216bfc | 2006-06-23 02:05:41 -0700 | [diff] [blame] | 41 | s64 percpu_counter_sum(struct percpu_counter *fbc) |
Ravikiran G Thirumalai | 3cbc564 | 2006-06-23 02:05:40 -0700 | [diff] [blame] | 42 | { |
Mingming Cao | 0216bfc | 2006-06-23 02:05:41 -0700 | [diff] [blame] | 43 | s64 ret; |
Ravikiran G Thirumalai | 3cbc564 | 2006-06-23 02:05:40 -0700 | [diff] [blame] | 44 | int cpu; |
| 45 | |
| 46 | spin_lock(&fbc->lock); |
| 47 | ret = fbc->count; |
Andrew Morton | b4ef0296 | 2007-07-15 23:39:51 -0700 | [diff] [blame] | 48 | for_each_online_cpu(cpu) { |
Mingming Cao | 0216bfc | 2006-06-23 02:05:41 -0700 | [diff] [blame] | 49 | s32 *pcount = per_cpu_ptr(fbc->counters, cpu); |
Ravikiran G Thirumalai | 3cbc564 | 2006-06-23 02:05:40 -0700 | [diff] [blame] | 50 | ret += *pcount; |
| 51 | } |
| 52 | spin_unlock(&fbc->lock); |
| 53 | return ret < 0 ? 0 : ret; |
| 54 | } |
| 55 | EXPORT_SYMBOL(percpu_counter_sum); |
Andrew Morton | c67ad91 | 2007-07-15 23:39:51 -0700 | [diff] [blame] | 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 |