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Diffstat (limited to 'fluent-bit/lib/jemalloc-5.3.0/include/jemalloc/internal/ticker.h')
| -rw-r--r-- | fluent-bit/lib/jemalloc-5.3.0/include/jemalloc/internal/ticker.h | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/fluent-bit/lib/jemalloc-5.3.0/include/jemalloc/internal/ticker.h b/fluent-bit/lib/jemalloc-5.3.0/include/jemalloc/internal/ticker.h new file mode 100644 index 00000000..6b51ddec --- /dev/null +++ b/fluent-bit/lib/jemalloc-5.3.0/include/jemalloc/internal/ticker.h @@ -0,0 +1,175 @@ +#ifndef JEMALLOC_INTERNAL_TICKER_H +#define JEMALLOC_INTERNAL_TICKER_H + +#include "jemalloc/internal/prng.h" +#include "jemalloc/internal/util.h" + +/** + * A ticker makes it easy to count-down events until some limit. You + * ticker_init the ticker to trigger every nticks events. You then notify it + * that an event has occurred with calls to ticker_tick (or that nticks events + * have occurred with a call to ticker_ticks), which will return true (and reset + * the counter) if the countdown hit zero. + */ +typedef struct ticker_s ticker_t; +struct ticker_s { + int32_t tick; + int32_t nticks; +}; + +static inline void +ticker_init(ticker_t *ticker, int32_t nticks) { + ticker->tick = nticks; + ticker->nticks = nticks; +} + +static inline void +ticker_copy(ticker_t *ticker, const ticker_t *other) { + *ticker = *other; +} + +static inline int32_t +ticker_read(const ticker_t *ticker) { + return ticker->tick; +} + +/* + * Not intended to be a public API. Unfortunately, on x86, neither gcc nor + * clang seems smart enough to turn + * ticker->tick -= nticks; + * if (unlikely(ticker->tick < 0)) { + * fixup ticker + * return true; + * } + * return false; + * into + * subq %nticks_reg, (%ticker_reg) + * js fixup ticker + * + * unless we force "fixup ticker" out of line. In that case, gcc gets it right, + * but clang now does worse than before. So, on x86 with gcc, we force it out + * of line, but otherwise let the inlining occur. Ordinarily this wouldn't be + * worth the hassle, but this is on the fast path of both malloc and free (via + * tcache_event). + */ +#if defined(__GNUC__) && !defined(__clang__) \ + && (defined(__x86_64__) || defined(__i386__)) +JEMALLOC_NOINLINE +#endif +static bool +ticker_fixup(ticker_t *ticker) { + ticker->tick = ticker->nticks; + return true; +} + +static inline bool +ticker_ticks(ticker_t *ticker, int32_t nticks) { + ticker->tick -= nticks; + if (unlikely(ticker->tick < 0)) { + return ticker_fixup(ticker); + } + return false; +} + +static inline bool +ticker_tick(ticker_t *ticker) { + return ticker_ticks(ticker, 1); +} + +/* + * Try to tick. If ticker would fire, return true, but rely on + * slowpath to reset ticker. + */ +static inline bool +ticker_trytick(ticker_t *ticker) { + --ticker->tick; + if (unlikely(ticker->tick < 0)) { + return true; + } + return false; +} + +/* + * The ticker_geom_t is much like the ticker_t, except that instead of ticker + * having a constant countdown, it has an approximate one; each tick has + * approximately a 1/nticks chance of triggering the count. + * + * The motivation is in triggering arena decay. With a naive strategy, each + * thread would maintain a ticker per arena, and check if decay is necessary + * each time that the arena's ticker fires. This has two costs: + * - Since under reasonable assumptions both threads and arenas can scale + * linearly with the number of CPUs, maintaining per-arena data in each thread + * scales quadratically with the number of CPUs. + * - These tickers are often a cache miss down tcache flush pathways. + * + * By giving each tick a 1/nticks chance of firing, we still maintain the same + * average number of ticks-until-firing per arena, with only a single ticker's + * worth of metadata. + */ + +/* See ticker.c for an explanation of these constants. */ +#define TICKER_GEOM_NBITS 6 +#define TICKER_GEOM_MUL 61 +extern const uint8_t ticker_geom_table[1 << TICKER_GEOM_NBITS]; + +/* Not actually any different from ticker_t; just for type safety. */ +typedef struct ticker_geom_s ticker_geom_t; +struct ticker_geom_s { + int32_t tick; + int32_t nticks; +}; + +/* + * Just pick the average delay for the first counter. We're more concerned with + * the behavior over long periods of time rather than the exact timing of the + * initial ticks. + */ +#define TICKER_GEOM_INIT(nticks) {nticks, nticks} + +static inline void +ticker_geom_init(ticker_geom_t *ticker, int32_t nticks) { + /* + * Make sure there's no overflow possible. This shouldn't really be a + * problem for reasonable nticks choices, which are all static and + * relatively small. + */ + assert((uint64_t)nticks * (uint64_t)255 / (uint64_t)TICKER_GEOM_MUL + <= (uint64_t)INT32_MAX); + ticker->tick = nticks; + ticker->nticks = nticks; +} + +static inline int32_t +ticker_geom_read(const ticker_geom_t *ticker) { + return ticker->tick; +} + +/* Same deal as above. */ +#if defined(__GNUC__) && !defined(__clang__) \ + && (defined(__x86_64__) || defined(__i386__)) +JEMALLOC_NOINLINE +#endif +static bool +ticker_geom_fixup(ticker_geom_t *ticker, uint64_t *prng_state) { + uint64_t idx = prng_lg_range_u64(prng_state, TICKER_GEOM_NBITS); + ticker->tick = (uint32_t)( + (uint64_t)ticker->nticks * (uint64_t)ticker_geom_table[idx] + / (uint64_t)TICKER_GEOM_MUL); + return true; +} + +static inline bool +ticker_geom_ticks(ticker_geom_t *ticker, uint64_t *prng_state, int32_t nticks) { + ticker->tick -= nticks; + if (unlikely(ticker->tick < 0)) { + return ticker_geom_fixup(ticker, prng_state); + } + return false; +} + +static inline bool +ticker_geom_tick(ticker_geom_t *ticker, uint64_t *prng_state) { + return ticker_geom_ticks(ticker, prng_state, 1); +} + +#endif /* JEMALLOC_INTERNAL_TICKER_H */ |