mirror of https://github.com/schoebel/mars
43 lines
1.0 KiB
C
43 lines
1.0 KiB
C
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// (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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int mars_limit(struct mars_limiter *lim, int amount)
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{
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int res = 0;
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unsigned long long now;
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now = cpu_clock(raw_smp_processor_id());
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if (lim->lim_max_rate > 0 && likely(lim->lim_stamp)) {
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long long elapsed = now - lim->lim_stamp;
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long long 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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lim->lim_accu += amount;
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rate = (long long)lim->lim_accu * LIMITER_TIME_RESOLUTION / elapsed;
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if (rate > lim->lim_max_rate) {
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res = 1001 - lim->lim_max_rate * 1000 / rate;
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}
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elapsed -= LIMITER_TIME_RESOLUTION * 2;
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if (elapsed > LIMITER_TIME_RESOLUTION) {
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lim->lim_stamp += elapsed;
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if (lim->lim_accu > 0)
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lim->lim_accu -= (long long)lim->lim_max_rate * elapsed / LIMITER_TIME_RESOLUTION;
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}
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} else {
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lim->lim_accu = amount;
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lim->lim_stamp = now;
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}
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return res;
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}
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EXPORT_SYMBOL_GPL(mars_limit);
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