Ravikiran G Thirumalai | 3cbc5640 | 2006-06-23 02:05:40 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * Fast batching percpu counters. |
| 3 | */ |
| 4 | |
| 5 | #include <linux/percpu_counter.h> |
| 6 | #include <linux/module.h> |
| 7 | |
| 8 | void percpu_counter_mod(struct percpu_counter *fbc, long amount) |
| 9 | { |
| 10 | long count; |
| 11 | long *pcount; |
| 12 | int cpu = get_cpu(); |
| 13 | |
| 14 | pcount = per_cpu_ptr(fbc->counters, cpu); |
| 15 | count = *pcount + amount; |
| 16 | if (count >= FBC_BATCH || count <= -FBC_BATCH) { |
| 17 | spin_lock(&fbc->lock); |
| 18 | fbc->count += count; |
| 19 | *pcount = 0; |
| 20 | spin_unlock(&fbc->lock); |
| 21 | } else { |
| 22 | *pcount = count; |
| 23 | } |
| 24 | put_cpu(); |
| 25 | } |
| 26 | EXPORT_SYMBOL(percpu_counter_mod); |
| 27 | |
| 28 | /* |
| 29 | * Add up all the per-cpu counts, return the result. This is a more accurate |
| 30 | * but much slower version of percpu_counter_read_positive() |
| 31 | */ |
| 32 | long percpu_counter_sum(struct percpu_counter *fbc) |
| 33 | { |
| 34 | long ret; |
| 35 | int cpu; |
| 36 | |
| 37 | spin_lock(&fbc->lock); |
| 38 | ret = fbc->count; |
| 39 | for_each_possible_cpu(cpu) { |
| 40 | long *pcount = per_cpu_ptr(fbc->counters, cpu); |
| 41 | ret += *pcount; |
| 42 | } |
| 43 | spin_unlock(&fbc->lock); |
| 44 | return ret < 0 ? 0 : ret; |
| 45 | } |
| 46 | EXPORT_SYMBOL(percpu_counter_sum); |