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MEDIUM: freq_ctr: reimplement freq_ctr_remain_period() from freq_ctr_total()

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Now the function becomes an inline one and only contains a divide and
a max. The divide will automatically go away with constant periods.
This commit is contained in:
Willy Tarreau 2021-04-11 10:42:28 +02:00
parent a7a31b2602
commit 607be24a85
2 changed files with 14 additions and 52 deletions
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16
include/haproxy/freq_ctr.h
View File

@ -148,6 +148,20 @@ static inline uint read_freq_ctr_period(struct freq_ctr_period *ctr, uint period
*/ */
unsigned int freq_ctr_remain(struct freq_ctr *ctr, unsigned int freq, unsigned int pend); unsigned int freq_ctr_remain(struct freq_ctr *ctr, unsigned int freq, unsigned int pend);
/* Returns the number of remaining events that can occur on this freq counter
* while respecting <freq> events per period, and taking into account that
* <pend> events are already known to be pending. Returns 0 if limit was reached.
*/
static inline uint freq_ctr_remain_period(struct freq_ctr_period *ctr, uint period, uint freq, uint pend)
{
ullong total = freq_ctr_total(ctr, period, pend);
uint avg = div64_32(total, period);
if (avg > freq)
avg = freq;
return freq - avg;
}
/* return the expected wait time in ms before the next event may occur, /* return the expected wait time in ms before the next event may occur,
* respecting frequency <freq>, and assuming there may already be some pending * respecting frequency <freq>, and assuming there may already be some pending
* events. It returns zero if we can proceed immediately, otherwise the wait * events. It returns zero if we can proceed immediately, otherwise the wait
@ -158,8 +172,6 @@ unsigned int next_event_delay(struct freq_ctr *ctr, unsigned int freq, unsigned
/* process freq counters over configurable periods */ /* process freq counters over configurable periods */
unsigned int read_freq_ctr_period(struct freq_ctr_period *ctr, unsigned int period); unsigned int read_freq_ctr_period(struct freq_ctr_period *ctr, unsigned int period);
unsigned int freq_ctr_remain_period(struct freq_ctr_period *ctr, unsigned int period,
unsigned int freq, unsigned int pend);
/* While the functions above report average event counts per period, we are /* While the functions above report average event counts per period, we are
* also interested in average values per event. For this we use a different * also interested in average values per event. For this we use a different

50
src/freq_ctr.c
View File

@ -166,56 +166,6 @@ unsigned int next_event_delay(struct freq_ctr *ctr, unsigned int freq, unsigned
return MAX(wait, 1); return MAX(wait, 1);
} }
/* Returns the number of remaining events that can occur on this freq counter
* while respecting <freq> events per period, and taking into account that
* <pend> events are already known to be pending. Returns 0 if limit was reached.
*/
unsigned int freq_ctr_remain_period(struct freq_ctr_period *ctr, unsigned int period,
unsigned int freq, unsigned int pend)
{
unsigned int _curr, _past, curr, past;
unsigned int remain, _curr_tick, curr_tick;
while (1) {
_curr = ctr->curr_ctr;
__ha_compiler_barrier();
_past = ctr->prev_ctr;
__ha_compiler_barrier();
_curr_tick = ctr->curr_tick;
__ha_compiler_barrier();
if (_curr_tick & 0x1)
continue;
curr = ctr->curr_ctr;
__ha_compiler_barrier();
past = ctr->prev_ctr;
__ha_compiler_barrier();
curr_tick = ctr->curr_tick;
__ha_compiler_barrier();
if (_curr == curr && _past == past && _curr_tick == curr_tick)
break;
};
remain = curr_tick + period - global_now_ms;
if (likely((int)remain < 0)) {
/* We're past the first period, check if we can still report a
* part of last period or if we're too far away.
*/
past = curr;
curr = 0;
remain += period;
if ((int)remain < 0)
past = 0;
}
if (likely(past))
curr += div64_32((unsigned long long)past * remain, period);
curr += pend;
freq -= curr;
if ((int)freq < 0)
freq = 0;
return freq;
}
/* Returns the total number of events over the current + last period, including /* Returns the total number of events over the current + last period, including
* a number of already pending events <pend>. The average frequency will be * a number of already pending events <pend>. The average frequency will be
* obtained by dividing the output by <period>. This is essentially made to * obtained by dividing the output by <period>. This is essentially made to