108 lines
2.1 KiB
C
108 lines
2.1 KiB
C
#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/config.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/smp.h>
|
|
#include <linux/threads.h>
|
|
#include <linux/percpu.h>
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
struct percpu_counter {
|
|
spinlock_t lock;
|
|
long count;
|
|
long *counters;
|
|
};
|
|
|
|
#if NR_CPUS >= 16
|
|
#define FBC_BATCH (NR_CPUS*2)
|
|
#else
|
|
#define FBC_BATCH (NR_CPUS*4)
|
|
#endif
|
|
|
|
static inline void percpu_counter_init(struct percpu_counter *fbc)
|
|
{
|
|
spin_lock_init(&fbc->lock);
|
|
fbc->count = 0;
|
|
fbc->counters = alloc_percpu(long);
|
|
}
|
|
|
|
static inline void percpu_counter_destroy(struct percpu_counter *fbc)
|
|
{
|
|
free_percpu(fbc->counters);
|
|
}
|
|
|
|
void percpu_counter_mod(struct percpu_counter *fbc, long amount);
|
|
|
|
static inline long 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 long percpu_counter_read_positive(struct percpu_counter *fbc)
|
|
{
|
|
long ret = fbc->count;
|
|
|
|
barrier(); /* Prevent reloads of fbc->count */
|
|
if (ret > 0)
|
|
return ret;
|
|
return 1;
|
|
}
|
|
|
|
#else
|
|
|
|
struct percpu_counter {
|
|
long count;
|
|
};
|
|
|
|
static inline void percpu_counter_init(struct percpu_counter *fbc)
|
|
{
|
|
fbc->count = 0;
|
|
}
|
|
|
|
static inline void percpu_counter_destroy(struct percpu_counter *fbc)
|
|
{
|
|
}
|
|
|
|
static inline void
|
|
percpu_counter_mod(struct percpu_counter *fbc, long amount)
|
|
{
|
|
preempt_disable();
|
|
fbc->count += amount;
|
|
preempt_enable();
|
|
}
|
|
|
|
static inline long percpu_counter_read(struct percpu_counter *fbc)
|
|
{
|
|
return fbc->count;
|
|
}
|
|
|
|
static inline long percpu_counter_read_positive(struct percpu_counter *fbc)
|
|
{
|
|
return fbc->count;
|
|
}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static inline void percpu_counter_inc(struct percpu_counter *fbc)
|
|
{
|
|
percpu_counter_mod(fbc, 1);
|
|
}
|
|
|
|
static inline void percpu_counter_dec(struct percpu_counter *fbc)
|
|
{
|
|
percpu_counter_mod(fbc, -1);
|
|
}
|
|
|
|
#endif /* _LINUX_PERCPU_COUNTER_H */
|