diff options
Diffstat (limited to 'deps/jemalloc/src/extent_dss.c')
| -rw-r--r-- | deps/jemalloc/src/extent_dss.c | 277 |
1 files changed, 277 insertions, 0 deletions
diff --git a/deps/jemalloc/src/extent_dss.c b/deps/jemalloc/src/extent_dss.c new file mode 100644 index 0000000..9a35bac --- /dev/null +++ b/deps/jemalloc/src/extent_dss.c @@ -0,0 +1,277 @@ +#include "jemalloc/internal/jemalloc_preamble.h" +#include "jemalloc/internal/jemalloc_internal_includes.h" + +#include "jemalloc/internal/assert.h" +#include "jemalloc/internal/extent_dss.h" +#include "jemalloc/internal/spin.h" + +/******************************************************************************/ +/* Data. */ + +const char *opt_dss = DSS_DEFAULT; + +const char *dss_prec_names[] = { + "disabled", + "primary", + "secondary", + "N/A" +}; + +/* + * Current dss precedence default, used when creating new arenas. NB: This is + * stored as unsigned rather than dss_prec_t because in principle there's no + * guarantee that sizeof(dss_prec_t) is the same as sizeof(unsigned), and we use + * atomic operations to synchronize the setting. + */ +static atomic_u_t dss_prec_default = ATOMIC_INIT( + (unsigned)DSS_PREC_DEFAULT); + +/* Base address of the DSS. */ +static void *dss_base; +/* Atomic boolean indicating whether a thread is currently extending DSS. */ +static atomic_b_t dss_extending; +/* Atomic boolean indicating whether the DSS is exhausted. */ +static atomic_b_t dss_exhausted; +/* Atomic current upper limit on DSS addresses. */ +static atomic_p_t dss_max; + +/******************************************************************************/ + +static void * +extent_dss_sbrk(intptr_t increment) { +#ifdef JEMALLOC_DSS + return sbrk(increment); +#else + not_implemented(); + return NULL; +#endif +} + +dss_prec_t +extent_dss_prec_get(void) { + dss_prec_t ret; + + if (!have_dss) { + return dss_prec_disabled; + } + ret = (dss_prec_t)atomic_load_u(&dss_prec_default, ATOMIC_ACQUIRE); + return ret; +} + +bool +extent_dss_prec_set(dss_prec_t dss_prec) { + if (!have_dss) { + return (dss_prec != dss_prec_disabled); + } + atomic_store_u(&dss_prec_default, (unsigned)dss_prec, ATOMIC_RELEASE); + return false; +} + +static void +extent_dss_extending_start(void) { + spin_t spinner = SPIN_INITIALIZER; + while (true) { + bool expected = false; + if (atomic_compare_exchange_weak_b(&dss_extending, &expected, + true, ATOMIC_ACQ_REL, ATOMIC_RELAXED)) { + break; + } + spin_adaptive(&spinner); + } +} + +static void +extent_dss_extending_finish(void) { + assert(atomic_load_b(&dss_extending, ATOMIC_RELAXED)); + + atomic_store_b(&dss_extending, false, ATOMIC_RELEASE); +} + +static void * +extent_dss_max_update(void *new_addr) { + /* + * Get the current end of the DSS as max_cur and assure that dss_max is + * up to date. + */ + void *max_cur = extent_dss_sbrk(0); + if (max_cur == (void *)-1) { + return NULL; + } + atomic_store_p(&dss_max, max_cur, ATOMIC_RELEASE); + /* Fixed new_addr can only be supported if it is at the edge of DSS. */ + if (new_addr != NULL && max_cur != new_addr) { + return NULL; + } + return max_cur; +} + +void * +extent_alloc_dss(tsdn_t *tsdn, arena_t *arena, void *new_addr, size_t size, + size_t alignment, bool *zero, bool *commit) { + edata_t *gap; + + cassert(have_dss); + assert(size > 0); + assert(alignment == ALIGNMENT_CEILING(alignment, PAGE)); + + /* + * sbrk() uses a signed increment argument, so take care not to + * interpret a large allocation request as a negative increment. + */ + if ((intptr_t)size < 0) { + return NULL; + } + + gap = edata_cache_get(tsdn, &arena->pa_shard.edata_cache); + if (gap == NULL) { + return NULL; + } + + extent_dss_extending_start(); + if (!atomic_load_b(&dss_exhausted, ATOMIC_ACQUIRE)) { + /* + * The loop is necessary to recover from races with other + * threads that are using the DSS for something other than + * malloc. + */ + while (true) { + void *max_cur = extent_dss_max_update(new_addr); + if (max_cur == NULL) { + goto label_oom; + } + + bool head_state = opt_retain ? EXTENT_IS_HEAD : + EXTENT_NOT_HEAD; + /* + * Compute how much page-aligned gap space (if any) is + * necessary to satisfy alignment. This space can be + * recycled for later use. + */ + void *gap_addr_page = (void *)(PAGE_CEILING( + (uintptr_t)max_cur)); + void *ret = (void *)ALIGNMENT_CEILING( + (uintptr_t)gap_addr_page, alignment); + size_t gap_size_page = (uintptr_t)ret - + (uintptr_t)gap_addr_page; + if (gap_size_page != 0) { + edata_init(gap, arena_ind_get(arena), + gap_addr_page, gap_size_page, false, + SC_NSIZES, extent_sn_next( + &arena->pa_shard.pac), + extent_state_active, false, true, + EXTENT_PAI_PAC, head_state); + } + /* + * Compute the address just past the end of the desired + * allocation space. + */ + void *dss_next = (void *)((uintptr_t)ret + size); + if ((uintptr_t)ret < (uintptr_t)max_cur || + (uintptr_t)dss_next < (uintptr_t)max_cur) { + goto label_oom; /* Wrap-around. */ + } + /* Compute the increment, including subpage bytes. */ + void *gap_addr_subpage = max_cur; + size_t gap_size_subpage = (uintptr_t)ret - + (uintptr_t)gap_addr_subpage; + intptr_t incr = gap_size_subpage + size; + + assert((uintptr_t)max_cur + incr == (uintptr_t)ret + + size); + + /* Try to allocate. */ + void *dss_prev = extent_dss_sbrk(incr); + if (dss_prev == max_cur) { + /* Success. */ + atomic_store_p(&dss_max, dss_next, + ATOMIC_RELEASE); + extent_dss_extending_finish(); + + if (gap_size_page != 0) { + ehooks_t *ehooks = arena_get_ehooks( + arena); + extent_dalloc_gap(tsdn, + &arena->pa_shard.pac, ehooks, gap); + } else { + edata_cache_put(tsdn, + &arena->pa_shard.edata_cache, gap); + } + if (!*commit) { + *commit = pages_decommit(ret, size); + } + if (*zero && *commit) { + edata_t edata = {0}; + ehooks_t *ehooks = arena_get_ehooks( + arena); + + edata_init(&edata, + arena_ind_get(arena), ret, size, + size, false, SC_NSIZES, + extent_state_active, false, true, + EXTENT_PAI_PAC, head_state); + if (extent_purge_forced_wrapper(tsdn, + ehooks, &edata, 0, size)) { + memset(ret, 0, size); + } + } + return ret; + } + /* + * Failure, whether due to OOM or a race with a raw + * sbrk() call from outside the allocator. + */ + if (dss_prev == (void *)-1) { + /* OOM. */ + atomic_store_b(&dss_exhausted, true, + ATOMIC_RELEASE); + goto label_oom; + } + } + } +label_oom: + extent_dss_extending_finish(); + edata_cache_put(tsdn, &arena->pa_shard.edata_cache, gap); + return NULL; +} + +static bool +extent_in_dss_helper(void *addr, void *max) { + return ((uintptr_t)addr >= (uintptr_t)dss_base && (uintptr_t)addr < + (uintptr_t)max); +} + +bool +extent_in_dss(void *addr) { + cassert(have_dss); + + return extent_in_dss_helper(addr, atomic_load_p(&dss_max, + ATOMIC_ACQUIRE)); +} + +bool +extent_dss_mergeable(void *addr_a, void *addr_b) { + void *max; + + cassert(have_dss); + + if ((uintptr_t)addr_a < (uintptr_t)dss_base && (uintptr_t)addr_b < + (uintptr_t)dss_base) { + return true; + } + + max = atomic_load_p(&dss_max, ATOMIC_ACQUIRE); + return (extent_in_dss_helper(addr_a, max) == + extent_in_dss_helper(addr_b, max)); +} + +void +extent_dss_boot(void) { + cassert(have_dss); + + dss_base = extent_dss_sbrk(0); + atomic_store_b(&dss_extending, false, ATOMIC_RELAXED); + atomic_store_b(&dss_exhausted, dss_base == (void *)-1, ATOMIC_RELAXED); + atomic_store_p(&dss_max, dss_base, ATOMIC_RELAXED); +} + +/******************************************************************************/ |