mirror of https://github.com/schoebel/mars
101 lines
2.9 KiB
C
101 lines
2.9 KiB
C
// (c) 2012 Thomas Schoebel-Theuer / 1&1 Internet AG
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#include "lib_limiter.h"
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#include <linux/kernel.h>
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#include <linux/module.h>
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#define LIMITER_TIME_RESOLUTION NSEC_PER_SEC
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int mars_limit(struct mars_limiter *lim, int amount)
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{
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int delay = 0;
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long long now;
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now = cpu_clock(raw_smp_processor_id());
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/* Compute the maximum delay along the path
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* down to the root of the hierarchy tree.
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*/
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while (lim != NULL) {
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long long window = now - lim->lim_stamp;
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/* Sometimes, raw CPU clocks may do weired things...
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* Smaller windows in the denominator than 1s could fake unrealistic rates.
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*/
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if (unlikely(lim->lim_min_window <= 0))
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lim->lim_min_window = 1000;
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if (unlikely(lim->lim_max_window <= lim->lim_min_window))
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lim->lim_max_window = lim->lim_min_window + 8000;
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if (unlikely(window < (long long)lim->lim_min_window * (LIMITER_TIME_RESOLUTION / 1000)))
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window = (long long)lim->lim_min_window * (LIMITER_TIME_RESOLUTION / 1000);
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/* Only use incremental accumulation at repeated calls, but
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* never after longer pauses.
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*/
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if (likely(lim->lim_stamp &&
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window < (long long)lim->lim_max_window * (LIMITER_TIME_RESOLUTION / 1000))) {
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long long rate_raw;
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int rate;
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/* Races are possible, but taken into account.
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* There is no real harm from rarely lost updates.
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*/
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if (likely(amount > 0)) {
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lim->lim_accu += amount;
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lim->lim_cumul += amount;
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lim->lim_count++;
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}
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rate_raw = lim->lim_accu * LIMITER_TIME_RESOLUTION / window;
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rate = rate_raw;
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if (unlikely(rate_raw > INT_MAX)) {
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rate = INT_MAX;
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}
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lim->lim_rate = rate;
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// limit exceeded?
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if (lim->lim_max_rate > 0 && rate > lim->lim_max_rate) {
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int this_delay = (window * rate / lim->lim_max_rate - window) / (LIMITER_TIME_RESOLUTION / 1000);
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// compute maximum
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if (this_delay > delay && this_delay > 0)
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delay = this_delay;
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}
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/* Try to keep the next window below min_window
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*/
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window -= lim->lim_min_window * (LIMITER_TIME_RESOLUTION / 1000);
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if (window > 0) {
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long long used_up = (long long)lim->lim_rate * window / LIMITER_TIME_RESOLUTION;
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if (used_up > 0) {
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lim->lim_stamp += window;
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lim->lim_accu -= used_up;
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if (unlikely(lim->lim_accu < 0))
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lim->lim_accu = 0;
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}
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}
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} else { // reset, start over with new measurement cycle
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if (unlikely(amount < 0))
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amount = 0;
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lim->lim_accu = amount;
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lim->lim_stamp = now - lim->lim_min_window * (LIMITER_TIME_RESOLUTION / 1000);
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lim->lim_rate = 0;
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}
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lim = lim->lim_father;
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}
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return delay;
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}
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EXPORT_SYMBOL_GPL(mars_limit);
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void mars_limit_sleep(struct mars_limiter *lim, int amount)
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{
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int sleep = mars_limit(lim, amount);
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if (sleep > 0) {
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if (unlikely(lim->lim_max_delay <= 0))
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lim->lim_max_delay = 1000;
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if (sleep > lim->lim_max_delay)
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sleep = lim->lim_max_delay;
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brick_msleep(sleep);
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}
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}
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EXPORT_SYMBOL_GPL(mars_limit_sleep);
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