diff options
Diffstat (limited to 'include/linux/percpu_counter.h')
| -rw-r--r-- | include/linux/percpu_counter.h | 125 |
1 files changed, 110 insertions, 15 deletions
diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h index ec065387f443..3a44dd1e33d2 100644 --- a/include/linux/percpu_counter.h +++ b/include/linux/percpu_counter.h @@ -1,3 +1,4 @@ +/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _LINUX_PERCPU_COUNTER_H #define _LINUX_PERCPU_COUNTER_H /* @@ -12,7 +13,9 @@ #include <linux/threads.h> #include <linux/percpu.h> #include <linux/types.h> -#include <linux/gfp.h> + +/* percpu_counter batch for local add or sub */ +#define PERCPU_COUNTER_LOCAL_BATCH INT_MAX #ifdef CONFIG_SMP @@ -27,22 +30,36 @@ struct percpu_counter { extern int percpu_counter_batch; -int __percpu_counter_init(struct percpu_counter *fbc, s64 amount, gfp_t gfp, - struct lock_class_key *key); +int __percpu_counter_init_many(struct percpu_counter *fbc, s64 amount, + gfp_t gfp, u32 nr_counters, + struct lock_class_key *key); -#define percpu_counter_init(fbc, value, gfp) \ +#define percpu_counter_init_many(fbc, value, gfp, nr_counters) \ ({ \ static struct lock_class_key __key; \ \ - __percpu_counter_init(fbc, value, gfp, &__key); \ + __percpu_counter_init_many(fbc, value, gfp, nr_counters,\ + &__key); \ }) -void percpu_counter_destroy(struct percpu_counter *fbc); + +#define percpu_counter_init(fbc, value, gfp) \ + percpu_counter_init_many(fbc, value, gfp, 1) + +void percpu_counter_destroy_many(struct percpu_counter *fbc, u32 nr_counters); +static inline void percpu_counter_destroy(struct percpu_counter *fbc) +{ + percpu_counter_destroy_many(fbc, 1); +} + void percpu_counter_set(struct percpu_counter *fbc, s64 amount); void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch); s64 __percpu_counter_sum(struct percpu_counter *fbc); int __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch); +bool __percpu_counter_limited_add(struct percpu_counter *fbc, s64 limit, + s64 amount, s32 batch); +void percpu_counter_sync(struct percpu_counter *fbc); static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs) { @@ -54,6 +71,29 @@ static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount) percpu_counter_add_batch(fbc, amount, percpu_counter_batch); } +static inline bool +percpu_counter_limited_add(struct percpu_counter *fbc, s64 limit, s64 amount) +{ + return __percpu_counter_limited_add(fbc, limit, amount, + percpu_counter_batch); +} + +/* + * With percpu_counter_add_local() and percpu_counter_sub_local(), counts + * are accumulated in local per cpu counter and not in fbc->count until + * local count overflows PERCPU_COUNTER_LOCAL_BATCH. This makes counter + * write efficient. + * But percpu_counter_sum(), instead of percpu_counter_read(), needs to be + * used to add up the counts from each CPU to account for all the local + * counts. So percpu_counter_add_local() and percpu_counter_sub_local() + * should be used when a counter is updated frequently and read rarely. + */ +static inline void +percpu_counter_add_local(struct percpu_counter *fbc, s64 amount) +{ + percpu_counter_add_batch(fbc, amount, PERCPU_COUNTER_LOCAL_BATCH); +} + static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc) { s64 ret = __percpu_counter_sum(fbc); @@ -77,15 +117,15 @@ static inline s64 percpu_counter_read(struct percpu_counter *fbc) */ static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc) { - s64 ret = fbc->count; + /* Prevent reloads of fbc->count */ + s64 ret = READ_ONCE(fbc->count); - barrier(); /* Prevent reloads of fbc->count */ if (ret >= 0) return ret; return 0; } -static inline int percpu_counter_initialized(struct percpu_counter *fbc) +static inline bool percpu_counter_initialized(struct percpu_counter *fbc) { return (fbc->counters != NULL); } @@ -96,11 +136,27 @@ struct percpu_counter { s64 count; }; +static inline int percpu_counter_init_many(struct percpu_counter *fbc, + s64 amount, gfp_t gfp, + u32 nr_counters) +{ + u32 i; + + for (i = 0; i < nr_counters; i++) + fbc[i].count = amount; + + return 0; +} + static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount, gfp_t gfp) { - fbc->count = amount; - return 0; + return percpu_counter_init_many(fbc, amount, gfp, 1); +} + +static inline void percpu_counter_destroy_many(struct percpu_counter *fbc, + u32 nr_counters) +{ } static inline void percpu_counter_destroy(struct percpu_counter *fbc) @@ -131,9 +187,39 @@ __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch) static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount) { - preempt_disable(); + unsigned long flags; + + local_irq_save(flags); fbc->count += amount; - preempt_enable(); + local_irq_restore(flags); +} + +static inline bool +percpu_counter_limited_add(struct percpu_counter *fbc, s64 limit, s64 amount) +{ + unsigned long flags; + bool good = false; + s64 count; + + if (amount == 0) + return true; + + local_irq_save(flags); + count = fbc->count + amount; + if ((amount > 0 && count <= limit) || + (amount < 0 && count >= limit)) { + fbc->count = count; + good = true; + } + local_irq_restore(flags); + return good; +} + +/* non-SMP percpu_counter_add_local is the same with percpu_counter_add */ +static inline void +percpu_counter_add_local(struct percpu_counter *fbc, s64 amount) +{ + percpu_counter_add(fbc, amount); } static inline void @@ -166,11 +252,14 @@ static inline s64 percpu_counter_sum(struct percpu_counter *fbc) return percpu_counter_read(fbc); } -static inline int percpu_counter_initialized(struct percpu_counter *fbc) +static inline bool percpu_counter_initialized(struct percpu_counter *fbc) { - return 1; + return true; } +static inline void percpu_counter_sync(struct percpu_counter *fbc) +{ +} #endif /* CONFIG_SMP */ static inline void percpu_counter_inc(struct percpu_counter *fbc) @@ -188,4 +277,10 @@ static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount) percpu_counter_add(fbc, -amount); } +static inline void +percpu_counter_sub_local(struct percpu_counter *fbc, s64 amount) +{ + percpu_counter_add_local(fbc, -amount); +} + #endif /* _LINUX_PERCPU_COUNTER_H */ |