server-skynet-source-3rd-je.../include/jemalloc/internal/rtree.h
David Goldblatt 79ae7f9211 Rtree: Remove the per-field accessors.
We instead split things into "edata" and "metadata".
2020-04-10 13:12:47 -07:00

425 lines
13 KiB
C

#ifndef JEMALLOC_INTERNAL_RTREE_H
#define JEMALLOC_INTERNAL_RTREE_H
#include "jemalloc/internal/atomic.h"
#include "jemalloc/internal/mutex.h"
#include "jemalloc/internal/rtree_tsd.h"
#include "jemalloc/internal/sc.h"
#include "jemalloc/internal/tsd.h"
/*
* This radix tree implementation is tailored to the singular purpose of
* associating metadata with extents that are currently owned by jemalloc.
*
*******************************************************************************
*/
/* Number of high insignificant bits. */
#define RTREE_NHIB ((1U << (LG_SIZEOF_PTR+3)) - LG_VADDR)
/* Number of low insigificant bits. */
#define RTREE_NLIB LG_PAGE
/* Number of significant bits. */
#define RTREE_NSB (LG_VADDR - RTREE_NLIB)
/* Number of levels in radix tree. */
#if RTREE_NSB <= 10
# define RTREE_HEIGHT 1
#elif RTREE_NSB <= 36
# define RTREE_HEIGHT 2
#elif RTREE_NSB <= 52
# define RTREE_HEIGHT 3
#else
# error Unsupported number of significant virtual address bits
#endif
/* Use compact leaf representation if virtual address encoding allows. */
#if RTREE_NHIB >= LG_CEIL(SC_NSIZES)
# define RTREE_LEAF_COMPACT
#endif
/* Needed for initialization only. */
#define RTREE_LEAFKEY_INVALID ((uintptr_t)1)
typedef struct rtree_node_elm_s rtree_node_elm_t;
struct rtree_node_elm_s {
atomic_p_t child; /* (rtree_{node,leaf}_elm_t *) */
};
typedef struct rtree_metadata_s rtree_metadata_t;
struct rtree_metadata_s {
szind_t szind;
bool slab;
};
typedef struct rtree_contents_s rtree_contents_t;
struct rtree_contents_s {
edata_t *edata;
rtree_metadata_t metadata;
};
struct rtree_leaf_elm_s {
#ifdef RTREE_LEAF_COMPACT
/*
* Single pointer-width field containing all three leaf element fields.
* For example, on a 64-bit x64 system with 48 significant virtual
* memory address bits, the index, edata, and slab fields are packed as
* such:
*
* x: index
* e: edata
* b: slab
*
* 00000000 xxxxxxxx eeeeeeee [...] eeeeeeee eeee000b
*/
atomic_p_t le_bits;
#else
atomic_p_t le_edata; /* (edata_t *) */
/*
* slab is stored in the low bit; szind is stored in the next lowest
* bits.
*/
atomic_u_t le_metadata;
#endif
};
typedef struct rtree_level_s rtree_level_t;
struct rtree_level_s {
/* Number of key bits distinguished by this level. */
unsigned bits;
/*
* Cumulative number of key bits distinguished by traversing to
* corresponding tree level.
*/
unsigned cumbits;
};
typedef struct rtree_s rtree_t;
struct rtree_s {
base_t *base;
malloc_mutex_t init_lock;
/* Number of elements based on rtree_levels[0].bits. */
#if RTREE_HEIGHT > 1
rtree_node_elm_t root[1U << (RTREE_NSB/RTREE_HEIGHT)];
#else
rtree_leaf_elm_t root[1U << (RTREE_NSB/RTREE_HEIGHT)];
#endif
};
/*
* Split the bits into one to three partitions depending on number of
* significant bits. It the number of bits does not divide evenly into the
* number of levels, place one remainder bit per level starting at the leaf
* level.
*/
static const rtree_level_t rtree_levels[] = {
#if RTREE_HEIGHT == 1
{RTREE_NSB, RTREE_NHIB + RTREE_NSB}
#elif RTREE_HEIGHT == 2
{RTREE_NSB/2, RTREE_NHIB + RTREE_NSB/2},
{RTREE_NSB/2 + RTREE_NSB%2, RTREE_NHIB + RTREE_NSB}
#elif RTREE_HEIGHT == 3
{RTREE_NSB/3, RTREE_NHIB + RTREE_NSB/3},
{RTREE_NSB/3 + RTREE_NSB%3/2,
RTREE_NHIB + RTREE_NSB/3*2 + RTREE_NSB%3/2},
{RTREE_NSB/3 + RTREE_NSB%3 - RTREE_NSB%3/2, RTREE_NHIB + RTREE_NSB}
#else
# error Unsupported rtree height
#endif
};
bool rtree_new(rtree_t *rtree, base_t *base, bool zeroed);
rtree_leaf_elm_t *rtree_leaf_elm_lookup_hard(tsdn_t *tsdn, rtree_t *rtree,
rtree_ctx_t *rtree_ctx, uintptr_t key, bool dependent, bool init_missing);
JEMALLOC_ALWAYS_INLINE uintptr_t
rtree_leafkey(uintptr_t key) {
unsigned ptrbits = ZU(1) << (LG_SIZEOF_PTR+3);
unsigned cumbits = (rtree_levels[RTREE_HEIGHT-1].cumbits -
rtree_levels[RTREE_HEIGHT-1].bits);
unsigned maskbits = ptrbits - cumbits;
uintptr_t mask = ~((ZU(1) << maskbits) - 1);
return (key & mask);
}
JEMALLOC_ALWAYS_INLINE size_t
rtree_cache_direct_map(uintptr_t key) {
unsigned ptrbits = ZU(1) << (LG_SIZEOF_PTR+3);
unsigned cumbits = (rtree_levels[RTREE_HEIGHT-1].cumbits -
rtree_levels[RTREE_HEIGHT-1].bits);
unsigned maskbits = ptrbits - cumbits;
return (size_t)((key >> maskbits) & (RTREE_CTX_NCACHE - 1));
}
JEMALLOC_ALWAYS_INLINE uintptr_t
rtree_subkey(uintptr_t key, unsigned level) {
unsigned ptrbits = ZU(1) << (LG_SIZEOF_PTR+3);
unsigned cumbits = rtree_levels[level].cumbits;
unsigned shiftbits = ptrbits - cumbits;
unsigned maskbits = rtree_levels[level].bits;
uintptr_t mask = (ZU(1) << maskbits) - 1;
return ((key >> shiftbits) & mask);
}
/*
* Atomic getters.
*
* dependent: Reading a value on behalf of a pointer to a valid allocation
* is guaranteed to be a clean read even without synchronization,
* because the rtree update became visible in memory before the
* pointer came into existence.
* !dependent: An arbitrary read, e.g. on behalf of ivsalloc(), may not be
* dependent on a previous rtree write, which means a stale read
* could result if synchronization were omitted here.
*/
# ifdef RTREE_LEAF_COMPACT
JEMALLOC_ALWAYS_INLINE uintptr_t
rtree_leaf_elm_bits_read(tsdn_t *tsdn, rtree_t *rtree,
rtree_leaf_elm_t *elm, bool dependent) {
return (uintptr_t)atomic_load_p(&elm->le_bits, dependent
? ATOMIC_RELAXED : ATOMIC_ACQUIRE);
}
JEMALLOC_ALWAYS_INLINE uintptr_t
rtree_leaf_elm_bits_encode(rtree_contents_t contents) {
uintptr_t edata_bits = (uintptr_t)contents.edata
& (((uintptr_t)1 << LG_VADDR) - 1);
uintptr_t szind_bits = (uintptr_t)contents.metadata.szind << LG_VADDR;
/*
* Slab shares the low bit of edata; we know edata is on an even address
* (in fact, it's 128 bytes on 64-bit systems; we can enforce this
* alignment if we want to steal 6 extra rtree leaf bits someday.
*/
uintptr_t slab_bits = (uintptr_t)contents.metadata.slab;
return szind_bits | edata_bits | slab_bits;
}
JEMALLOC_ALWAYS_INLINE rtree_contents_t
rtree_leaf_elm_bits_decode(uintptr_t bits) {
rtree_contents_t contents;
/* Do the easy things first. */
contents.metadata.szind = bits >> LG_VADDR;
contents.metadata.slab = (bool)(bits & 1);
# ifdef __aarch64__
/*
* aarch64 doesn't sign extend the highest virtual address bit to set
* the higher ones. Instead, the high bits get zeroed.
*/
uintptr_t high_bit_mask = ((uintptr_t)1 << LG_VADDR) - 1;
/* Mask off the slab bit. */
uintptr_t low_bit_mask = ~(uintptr_t)1;
uintptr_t mask = high_bit_mask & low_bit_mask;
contents.edata = (edata_t *)(bits & mask);
# else
/* Restore sign-extended high bits, mask slab bit. */
contents.edata = (edata_t *)((uintptr_t)((intptr_t)(bits << RTREE_NHIB)
>> RTREE_NHIB) & ~((uintptr_t)0x1));
# endif
return contents;
}
# endif /* RTREE_LEAF_COMPACT */
JEMALLOC_ALWAYS_INLINE rtree_contents_t
rtree_leaf_elm_read(tsdn_t *tsdn, rtree_t *rtree, rtree_leaf_elm_t *elm,
bool dependent) {
#ifdef RTREE_LEAF_COMPACT
uintptr_t bits = rtree_leaf_elm_bits_read(tsdn, rtree, elm, dependent);
rtree_contents_t contents = rtree_leaf_elm_bits_decode(bits);
return contents;
#else
rtree_contents_t contents;
unsigned metadata_bits = atomic_load_u(&elm->le_metadata, dependent
? ATOMIC_RELAXED : ATOMIC_ACQUIRE);
contents.metadata.slab = (bool)(metadata_bits & 1);
contents.metadata.szind = (metadata_bits >> 1);
contents.edata = (edata_t *)atomic_load_p(&elm->le_edata, dependent
? ATOMIC_RELAXED : ATOMIC_ACQUIRE);
return contents;
#endif
}
static inline void
rtree_leaf_elm_write(tsdn_t *tsdn, rtree_t *rtree,
rtree_leaf_elm_t *elm, rtree_contents_t contents) {
#ifdef RTREE_LEAF_COMPACT
uintptr_t bits = rtree_leaf_elm_bits_encode(contents);
atomic_store_p(&elm->le_bits, (void *)bits, ATOMIC_RELEASE);
#else
unsigned metadata_bits = ((unsigned)contents.metadata.slab
| ((unsigned)contents.metadata.szind << 1));
atomic_store_u(&elm->le_metadata, metadata_bits, ATOMIC_RELEASE);
/*
* Write edata last, since the element is atomically considered valid
* as soon as the edata field is non-NULL.
*/
atomic_store_p(&elm->le_edata, contents.edata, ATOMIC_RELEASE);
#endif
}
/*
* Tries to look up the key in the L1 cache, returning it if there's a hit, or
* NULL if there's a miss.
* Key is allowed to be NULL; returns NULL in this case.
*/
JEMALLOC_ALWAYS_INLINE rtree_leaf_elm_t *
rtree_leaf_elm_lookup_fast(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key) {
rtree_leaf_elm_t *elm;
size_t slot = rtree_cache_direct_map(key);
uintptr_t leafkey = rtree_leafkey(key);
assert(leafkey != RTREE_LEAFKEY_INVALID);
if (likely(rtree_ctx->cache[slot].leafkey == leafkey)) {
rtree_leaf_elm_t *leaf = rtree_ctx->cache[slot].leaf;
assert(leaf != NULL);
uintptr_t subkey = rtree_subkey(key, RTREE_HEIGHT-1);
elm = &leaf[subkey];
return elm;
} else {
return NULL;
}
}
JEMALLOC_ALWAYS_INLINE rtree_leaf_elm_t *
rtree_leaf_elm_lookup(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key, bool dependent, bool init_missing) {
assert(key != 0);
assert(!dependent || !init_missing);
size_t slot = rtree_cache_direct_map(key);
uintptr_t leafkey = rtree_leafkey(key);
assert(leafkey != RTREE_LEAFKEY_INVALID);
/* Fast path: L1 direct mapped cache. */
if (likely(rtree_ctx->cache[slot].leafkey == leafkey)) {
rtree_leaf_elm_t *leaf = rtree_ctx->cache[slot].leaf;
assert(leaf != NULL);
uintptr_t subkey = rtree_subkey(key, RTREE_HEIGHT-1);
return &leaf[subkey];
}
/*
* Search the L2 LRU cache. On hit, swap the matching element into the
* slot in L1 cache, and move the position in L2 up by 1.
*/
#define RTREE_CACHE_CHECK_L2(i) do { \
if (likely(rtree_ctx->l2_cache[i].leafkey == leafkey)) { \
rtree_leaf_elm_t *leaf = rtree_ctx->l2_cache[i].leaf; \
assert(leaf != NULL); \
if (i > 0) { \
/* Bubble up by one. */ \
rtree_ctx->l2_cache[i].leafkey = \
rtree_ctx->l2_cache[i - 1].leafkey; \
rtree_ctx->l2_cache[i].leaf = \
rtree_ctx->l2_cache[i - 1].leaf; \
rtree_ctx->l2_cache[i - 1].leafkey = \
rtree_ctx->cache[slot].leafkey; \
rtree_ctx->l2_cache[i - 1].leaf = \
rtree_ctx->cache[slot].leaf; \
} else { \
rtree_ctx->l2_cache[0].leafkey = \
rtree_ctx->cache[slot].leafkey; \
rtree_ctx->l2_cache[0].leaf = \
rtree_ctx->cache[slot].leaf; \
} \
rtree_ctx->cache[slot].leafkey = leafkey; \
rtree_ctx->cache[slot].leaf = leaf; \
uintptr_t subkey = rtree_subkey(key, RTREE_HEIGHT-1); \
return &leaf[subkey]; \
} \
} while (0)
/* Check the first cache entry. */
RTREE_CACHE_CHECK_L2(0);
/* Search the remaining cache elements. */
for (unsigned i = 1; i < RTREE_CTX_NCACHE_L2; i++) {
RTREE_CACHE_CHECK_L2(i);
}
#undef RTREE_CACHE_CHECK_L2
return rtree_leaf_elm_lookup_hard(tsdn, rtree, rtree_ctx, key,
dependent, init_missing);
}
/*
* Returns true on lookup failure.
*/
static inline bool
rtree_read_independent(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key, rtree_contents_t *r_contents) {
rtree_leaf_elm_t *elm = rtree_leaf_elm_lookup(tsdn, rtree, rtree_ctx,
key, /* dependent */ false, /* init_missing */ false);
if (elm == NULL) {
return true;
}
*r_contents = rtree_leaf_elm_read(tsdn, rtree, elm,
/* dependent */ false);
return false;
}
static inline rtree_contents_t
rtree_read(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key) {
rtree_leaf_elm_t *elm = rtree_leaf_elm_lookup(tsdn, rtree, rtree_ctx,
key, /* dependent */ true, /* init_missing */ false);
assert(elm != NULL);
return rtree_leaf_elm_read(tsdn, rtree, elm, /* dependent */ true);
}
static inline rtree_metadata_t
rtree_metadata_read(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key) {
rtree_leaf_elm_t *elm = rtree_leaf_elm_lookup(tsdn, rtree, rtree_ctx,
key, /* dependent */ true, /* init_missing */ false);
assert(elm != NULL);
return rtree_leaf_elm_read(tsdn, rtree, elm,
/* dependent */ true).metadata;
}
/*
* Returns true on error.
*/
static inline bool
rtree_metadata_try_read_fast(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key, rtree_metadata_t *r_rtree_metadata) {
rtree_leaf_elm_t *elm = rtree_leaf_elm_lookup_fast(tsdn, rtree, rtree_ctx,
key);
if (elm == NULL) {
return true;
}
*r_rtree_metadata = rtree_leaf_elm_read(tsdn, rtree, elm,
/* dependent */ true).metadata;
return false;
}
static inline bool
rtree_write(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx, uintptr_t key,
rtree_contents_t contents) {
rtree_leaf_elm_t *elm = rtree_leaf_elm_lookup(tsdn, rtree, rtree_ctx,
key, /* dependent */ false, /* init_missing */ true);
if (elm == NULL) {
return true;
}
rtree_leaf_elm_write(tsdn, rtree, elm, contents);
return false;
}
static inline void
rtree_clear(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key) {
rtree_leaf_elm_t *elm = rtree_leaf_elm_lookup(tsdn, rtree, rtree_ctx,
key, /* dependent */ true, /* init_missing */ false);
assert(elm != NULL);
assert(rtree_leaf_elm_read(tsdn, rtree, elm,
/* dependent */ true).edata != NULL);
rtree_contents_t contents;
contents.edata = NULL;
contents.metadata.szind = SC_NSIZES;
contents.metadata.slab = false;
rtree_leaf_elm_write(tsdn, rtree, elm, contents);
}
#endif /* JEMALLOC_INTERNAL_RTREE_H */