| #ifndef _LINUX_PERCPU_COUNTER_H |
| #define _LINUX_PERCPU_COUNTER_H |
| /* |
| * A simple "approximate counter" for use in ext2 and ext3 superblocks. |
| * |
| * WARNING: these things are HUGE. 4 kbytes per counter on 32-way P4. |
| */ |
| |
| #include <linux/spinlock.h> |
| #include <linux/smp.h> |
| #include <linux/list.h> |
| #include <linux/threads.h> |
| #include <linux/percpu.h> |
| #include <linux/types.h> |
| |
| #ifdef CONFIG_SMP |
| |
| struct percpu_counter { |
| spinlock_t lock; |
| s64 count; |
| #ifdef CONFIG_HOTPLUG_CPU |
| struct list_head list; /* All percpu_counters are on a list */ |
| #endif |
| s32 *counters; |
| }; |
| |
| #if NR_CPUS >= 16 |
| #define FBC_BATCH (NR_CPUS*2) |
| #else |
| #define FBC_BATCH (NR_CPUS*4) |
| #endif |
| |
| void percpu_counter_init(struct percpu_counter *fbc, s64 amount); |
| void percpu_counter_destroy(struct percpu_counter *fbc); |
| void percpu_counter_set(struct percpu_counter *fbc, s64 amount); |
| void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch); |
| s64 __percpu_counter_sum(struct percpu_counter *fbc); |
| |
| static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount) |
| { |
| __percpu_counter_add(fbc, amount, FBC_BATCH); |
| } |
| |
| static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc) |
| { |
| s64 ret = __percpu_counter_sum(fbc); |
| return ret < 0 ? 0 : ret; |
| } |
| |
| static inline s64 percpu_counter_sum(struct percpu_counter *fbc) |
| { |
| return __percpu_counter_sum(fbc); |
| } |
| |
| static inline s64 percpu_counter_read(struct percpu_counter *fbc) |
| { |
| return fbc->count; |
| } |
| |
| /* |
| * It is possible for the percpu_counter_read() to return a small negative |
| * number for some counter which should never be negative. |
| * |
| */ |
| static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc) |
| { |
| s64 ret = fbc->count; |
| |
| barrier(); /* Prevent reloads of fbc->count */ |
| if (ret >= 0) |
| return ret; |
| return 1; |
| } |
| |
| #else |
| |
| struct percpu_counter { |
| s64 count; |
| }; |
| |
| static inline void percpu_counter_init(struct percpu_counter *fbc, s64 amount) |
| { |
| fbc->count = amount; |
| } |
| |
| static inline void percpu_counter_destroy(struct percpu_counter *fbc) |
| { |
| } |
| |
| static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount) |
| { |
| fbc->count = amount; |
| } |
| |
| #define __percpu_counter_add(fbc, amount, batch) \ |
| percpu_counter_add(fbc, amount) |
| |
| static inline void |
| percpu_counter_add(struct percpu_counter *fbc, s64 amount) |
| { |
| preempt_disable(); |
| fbc->count += amount; |
| preempt_enable(); |
| } |
| |
| static inline s64 percpu_counter_read(struct percpu_counter *fbc) |
| { |
| return fbc->count; |
| } |
| |
| static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc) |
| { |
| return fbc->count; |
| } |
| |
| static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc) |
| { |
| return percpu_counter_read_positive(fbc); |
| } |
| |
| static inline s64 percpu_counter_sum(struct percpu_counter *fbc) |
| { |
| return percpu_counter_read(fbc); |
| } |
| |
| #endif /* CONFIG_SMP */ |
| |
| static inline void percpu_counter_inc(struct percpu_counter *fbc) |
| { |
| percpu_counter_add(fbc, 1); |
| } |
| |
| static inline void percpu_counter_dec(struct percpu_counter *fbc) |
| { |
| percpu_counter_add(fbc, -1); |
| } |
| |
| static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount) |
| { |
| percpu_counter_add(fbc, -amount); |
| } |
| |
| #endif /* _LINUX_PERCPU_COUNTER_H */ |