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LFU: make counter log factor and decay time configurable.

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This commit is contained in:
antirez
2016-07-20 15:00:35 +02:00
parent 6416ab19d0
commit 6854c7b9ee
5 changed files with 95 additions and 14 deletions
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5
src/evict.c
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@ -287,13 +287,12 @@ unsigned long LFUTimeElapsed(unsigned long ldt) {
/* Logarithmically increment a counter. The greater is the current counter value
* the less likely is that it gets really implemented. Saturate it at 255. */
#define LFU_LOG_FACTOR 10
uint8_t LFULogIncr(uint8_t counter) {
if (counter == 255) return 255;
double r = (double)rand()/RAND_MAX;
double baseval = counter - LFU_INIT_VAL;
if (baseval < 0) baseval = 0;
double p = 1.0/(baseval*LFU_LOG_FACTOR+1);
double p = 1.0/(baseval*server.lfu_log_factor+1);
if (r < p) counter++;
return counter;
}
@ -308,7 +307,7 @@ uint8_t LFULogIncr(uint8_t counter) {
unsigned long LFUDecrAndReturn(robj *o) {
unsigned long ldt = o->lru >> 8;
unsigned long counter = o->lru & 255;
if (LFUTimeElapsed(ldt) >= LFU_DECR_INTERVAL && counter) {
if (LFUTimeElapsed(ldt) >= server.lfu_decay_time && counter) {
if (counter > LFU_INIT_VAL*2) {
counter /= 2;
if (counter < LFU_INIT_VAL*2) counter = LFU_INIT_VAL*2;