mars/lib_limiter.h

65 lines
1.4 KiB
C

// (c) 2012 Thomas Schoebel-Theuer / 1&1 Internet AG
#ifndef MARS_LIB_LIMITER_H
#define MARS_LIB_LIMITER_H
#include <linux/utsname.h>
#define LIMITER_TIME_RESOLUTION NSEC_PER_SEC
struct mars_limiter {
/* tunables */
int lim_max_rate;
/* internal */
int lim_accu;
unsigned long long lim_stamp;
};
extern inline
int mars_limit(struct mars_limiter *lim, int amount)
{
int res = 0;
unsigned long long now;
now = cpu_clock(raw_smp_processor_id());
if (lim->lim_max_rate > 0 && likely(lim->lim_stamp)) {
long long elapsed = now - lim->lim_stamp;
long long rate;
/* Races are possible, but taken into account.
* There is no real harm from rarely lost updates.
*/
lim->lim_accu += amount;
rate = (long long)lim->lim_accu * LIMITER_TIME_RESOLUTION / elapsed;
if (rate > lim->lim_max_rate) {
res = 1001 - lim->lim_max_rate * 1000 / rate;
}
elapsed -= LIMITER_TIME_RESOLUTION * 2;
if (elapsed > LIMITER_TIME_RESOLUTION) {
lim->lim_stamp += elapsed;
if (lim->lim_accu > 0)
lim->lim_accu -= (long long)lim->lim_max_rate * elapsed / LIMITER_TIME_RESOLUTION;
}
} else {
lim->lim_accu = amount;
lim->lim_stamp = now;
}
return res;
}
extern inline
void mars_limit_sleep(struct mars_limiter *lim, int amount)
{
int sleep = mars_limit(lim, amount);
if (sleep > 0) {
if (sleep > 1000)
sleep = 1000;
brick_msleep(sleep);
}
}
#endif