diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Makefile | 1 | ||||
| -rw-r--r-- | lib/percpu_counter.c | 46 |
2 files changed, 47 insertions, 0 deletions
diff --git a/lib/Makefile b/lib/Makefile index b830c9a15541..79358ad1f113 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -46,6 +46,7 @@ obj-$(CONFIG_TEXTSEARCH) += textsearch.o obj-$(CONFIG_TEXTSEARCH_KMP) += ts_kmp.o obj-$(CONFIG_TEXTSEARCH_BM) += ts_bm.o obj-$(CONFIG_TEXTSEARCH_FSM) += ts_fsm.o +obj-$(CONFIG_SMP) += percpu_counter.o obj-$(CONFIG_SWIOTLB) += swiotlb.o diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c new file mode 100644 index 000000000000..7a87003f8e8f --- /dev/null +++ b/lib/percpu_counter.c @@ -0,0 +1,46 @@ +/* + * Fast batching percpu counters. + */ + +#include <linux/percpu_counter.h> +#include <linux/module.h> + +void percpu_counter_mod(struct percpu_counter *fbc, long amount) +{ + long count; + long *pcount; + int cpu = get_cpu(); + + pcount = per_cpu_ptr(fbc->counters, cpu); + count = *pcount + amount; + if (count >= FBC_BATCH || count <= -FBC_BATCH) { + spin_lock(&fbc->lock); + fbc->count += count; + *pcount = 0; + spin_unlock(&fbc->lock); + } else { + *pcount = count; + } + put_cpu(); +} +EXPORT_SYMBOL(percpu_counter_mod); + +/* + * Add up all the per-cpu counts, return the result. This is a more accurate + * but much slower version of percpu_counter_read_positive() + */ +long percpu_counter_sum(struct percpu_counter *fbc) +{ + long ret; + int cpu; + + spin_lock(&fbc->lock); + ret = fbc->count; + for_each_possible_cpu(cpu) { + long *pcount = per_cpu_ptr(fbc->counters, cpu); + ret += *pcount; + } + spin_unlock(&fbc->lock); + return ret < 0 ? 0 : ret; +} +EXPORT_SYMBOL(percpu_counter_sum); |