83 lines
2.2 KiB
C
83 lines
2.2 KiB
C
|
#ifndef JEMALLOC_INTERNAL_CACHE_BIN_H
|
||
|
|
#define JEMALLOC_INTERNAL_CACHE_BIN_H
|
||
|
|
|
||
|
|
/*
|
||
|
|
* The count of the number of cached allocations in a bin. We make this signed
|
||
|
|
* so that negative numbers can encode "invalid" states (e.g. a low water mark
|
||
|
|
* for a bin that has never been filled).
|
||
|
|
*/
|
||
|
|
typedef int32_t cache_bin_sz_t;
|
||
|
|
|
||
|
|
typedef struct cache_bin_stats_s cache_bin_stats_t;
|
||
|
|
struct cache_bin_stats_s {
|
||
|
|
/*
|
||
|
|
* Number of allocation requests that corresponded to the size of this
|
||
|
|
* bin.
|
||
|
|
*/
|
||
|
|
uint64_t nrequests;
|
||
|
|
};
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Read-only information associated with each element of tcache_t's tbins array
|
||
|
|
* is stored separately, mainly to reduce memory usage.
|
||
|
|
*/
|
||
|
|
typedef struct cache_bin_info_s cache_bin_info_t;
|
||
|
|
struct cache_bin_info_s {
|
||
|
|
/* Upper limit on ncached. */
|
||
|
|
cache_bin_sz_t ncached_max;
|
||
|
|
};
|
||
|
|
|
||
|
|
typedef struct cache_bin_s cache_bin_t;
|
||
|
|
struct cache_bin_s {
|
||
|
|
/* Min # cached since last GC. */
|
||
|
|
cache_bin_sz_t low_water;
|
||
|
|
/* # of cached objects. */
|
||
|
|
cache_bin_sz_t ncached;
|
||
|
|
/*
|
||
|
|
* ncached and stats are both modified frequently. Let's keep them
|
||
|
|
* close so that they have a higher chance of being on the same
|
||
|
|
* cacheline, thus less write-backs.
|
||
|
|
*/
|
||
|
|
cache_bin_stats_t tstats;
|
||
|
|
/*
|
||
|
|
* Stack of available objects.
|
||
|
|
*
|
||
|
|
* To make use of adjacent cacheline prefetch, the items in the avail
|
||
|
|
* stack goes to higher address for newer allocations. avail points
|
||
|
|
* just above the available space, which means that
|
||
|
|
* avail[-ncached, ... -1] are available items and the lowest item will
|
||
|
|
* be allocated first.
|
||
|
|
*/
|
||
|
|
void **avail;
|
||
|
|
};
|
||
|
|
|
||
|
|
JEMALLOC_ALWAYS_INLINE void *
|
||
|
|
cache_alloc_easy(cache_bin_t *bin, bool *success) {
|
||
|
|
void *ret;
|
||
|
|
|
||
|
|
if (unlikely(bin->ncached == 0)) {
|
||
|
|
bin->low_water = -1;
|
||
|
|
*success = false;
|
||
|
|
return NULL;
|
||
|
|
}
|
||
|
|
/*
|
||
|
|
* success (instead of ret) should be checked upon the return of this
|
||
|
|
* function. We avoid checking (ret == NULL) because there is never a
|
||
|
|
* null stored on the avail stack (which is unknown to the compiler),
|
||
|
|
* and eagerly checking ret would cause pipeline stall (waiting for the
|
||
|
|
* cacheline).
|
||
|
|
*/
|
||
|
|
*success = true;
|
||
|
|
ret = *(bin->avail - bin->ncached);
|
||
|
|
bin->ncached--;
|
||
|
|
|
||
|
|
if (unlikely(bin->ncached < bin->low_water)) {
|
||
|
|
bin->low_water = bin->ncached;
|
||
|
|
}
|
||
|
|
|
||
|
|
return ret;
|
||
|
|
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif /* JEMALLOC_INTERNAL_CACHE_BIN_H */
|