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Refactor arena_mapbits unzeroed flag management.

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Only set the unzeroed flag when initializing the entire mapbits entry,
rather than mutating just the unzeroed bit.  This simplifies the
possible mapbits state transitions.
This commit is contained in:
Jason Evans 2015-08-10 23:03:34 -07:00
parent de249c8679
commit 45186f0c07
4 changed files with 35 additions and 37 deletions
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25
include/jemalloc/internal/arena.h
View File

@ -534,14 +534,14 @@ void arena_mapbits_unallocated_set(arena_chunk_t *chunk, size_t pageind,
size_t size, size_t flags);
void arena_mapbits_unallocated_size_set(arena_chunk_t *chunk, size_t pageind,
size_t size);
void arena_mapbits_internal_set(arena_chunk_t *chunk, size_t pageind,
size_t flags);
void arena_mapbits_large_set(arena_chunk_t *chunk, size_t pageind,
size_t size, size_t flags);
void arena_mapbits_large_binind_set(arena_chunk_t *chunk, size_t pageind,
index_t binind);
void arena_mapbits_small_set(arena_chunk_t *chunk, size_t pageind,
size_t runind, index_t binind, size_t flags);
void arena_mapbits_unzeroed_set(arena_chunk_t *chunk, size_t pageind,
size_t unzeroed);
void arena_metadata_allocated_add(arena_t *arena, size_t size);
void arena_metadata_allocated_sub(arena_t *arena, size_t size);
size_t arena_metadata_allocated_get(arena_t *arena);
@ -783,6 +783,15 @@ arena_mapbits_unallocated_size_set(arena_chunk_t *chunk, size_t pageind,
& ~CHUNK_MAP_SIZE_MASK));
}
JEMALLOC_ALWAYS_INLINE void
arena_mapbits_internal_set(arena_chunk_t *chunk, size_t pageind, size_t flags)
{
size_t *mapbitsp = arena_mapbitsp_get(chunk, pageind);
assert((flags & CHUNK_MAP_UNZEROED) == flags);
arena_mapbitsp_write(mapbitsp, flags);
}
JEMALLOC_ALWAYS_INLINE void
arena_mapbits_large_set(arena_chunk_t *chunk, size_t pageind, size_t size,
size_t flags)
@ -831,18 +840,6 @@ arena_mapbits_small_set(arena_chunk_t *chunk, size_t pageind, size_t runind,
CHUNK_MAP_ALLOCATED);
}
JEMALLOC_ALWAYS_INLINE void
arena_mapbits_unzeroed_set(arena_chunk_t *chunk, size_t pageind,
size_t unzeroed)
{
size_t *mapbitsp = arena_mapbitsp_get(chunk, pageind);
size_t mapbits = arena_mapbitsp_read(mapbitsp);
assert((mapbits & CHUNK_MAP_DECOMMITTED) == 0 || !unzeroed);
arena_mapbitsp_write(mapbitsp, (mapbits & ~CHUNK_MAP_UNZEROED) |
unzeroed);
}
JEMALLOC_INLINE void
arena_metadata_allocated_add(arena_t *arena, size_t size)
{

2
include/jemalloc/internal/private_symbols.txt
View File

@ -42,6 +42,7 @@ arena_mapbits_binind_get
arena_mapbits_decommitted_get
arena_mapbits_dirty_get
arena_mapbits_get
arena_mapbits_internal_set
arena_mapbits_large_binind_set
arena_mapbits_large_get
arena_mapbits_large_set
@ -52,7 +53,6 @@ arena_mapbits_unallocated_set
arena_mapbits_unallocated_size_get
arena_mapbits_unallocated_size_set
arena_mapbits_unzeroed_get
arena_mapbits_unzeroed_set
arena_mapbitsp_get
arena_mapbitsp_read
arena_mapbitsp_write

43
src/arena.c
View File

@ -642,7 +642,7 @@ arena_chunk_init_hard(arena_t *arena)
{
arena_chunk_t *chunk;
bool zero, commit;
size_t unzeroed, decommitted, i;
size_t flag_unzeroed, flag_decommitted, i;
assert(arena->spare == NULL);
@ -657,10 +657,10 @@ arena_chunk_init_hard(arena_t *arena)
* the pages as zeroed if chunk_alloc() returned a zeroed or decommitted
* chunk.
*/
unzeroed = (zero || !commit) ? 0 : CHUNK_MAP_UNZEROED;
decommitted = commit ? 0 : CHUNK_MAP_DECOMMITTED;
arena_mapbits_unallocated_set(chunk, map_bias, arena_maxrun, unzeroed |
decommitted);
flag_unzeroed = (zero || !commit) ? 0 : CHUNK_MAP_UNZEROED;
flag_decommitted = commit ? 0 : CHUNK_MAP_DECOMMITTED;
arena_mapbits_unallocated_set(chunk, map_bias, arena_maxrun,
flag_unzeroed | flag_decommitted);
/*
* There is no need to initialize the internal page map entries unless
* the chunk is not zeroed.
@ -672,7 +672,7 @@ arena_chunk_init_hard(arena_t *arena)
chunk_npages-1) - (uintptr_t)arena_bitselm_get(chunk,
map_bias+1)));
for (i = map_bias+1; i < chunk_npages-1; i++)
arena_mapbits_unzeroed_set(chunk, i, unzeroed);
arena_mapbits_internal_set(chunk, i, flag_unzeroed);
} else {
JEMALLOC_VALGRIND_MAKE_MEM_DEFINED((void
*)arena_bitselm_get(chunk, map_bias+1), (size_t)((uintptr_t)
@ -681,12 +681,12 @@ arena_chunk_init_hard(arena_t *arena)
if (config_debug) {
for (i = map_bias+1; i < chunk_npages-1; i++) {
assert(arena_mapbits_unzeroed_get(chunk, i) ==
unzeroed);
flag_unzeroed);
}
}
}
arena_mapbits_unallocated_set(chunk, chunk_npages-1, arena_maxrun,
unzeroed);
flag_unzeroed);
return (chunk);
}
@ -1391,8 +1391,8 @@ arena_purge_stashed(arena_t *arena, chunk_hooks_t *chunk_hooks,
npages = size >> LG_PAGE;
chunkselm = qr_next(chunkselm, cc_link);
} else {
size_t pageind, run_size, flag_unzeroed, i;
bool unzeroed, decommitted;
size_t pageind, run_size, flag_unzeroed, flags, i;
bool decommitted;
arena_chunk_t *chunk =
(arena_chunk_t *)CHUNK_ADDR2BASE(rdelm);
arena_chunk_map_misc_t *miscelm =
@ -1408,20 +1408,21 @@ arena_purge_stashed(arena_t *arena, chunk_hooks_t *chunk_hooks,
decommitted = !chunk_hooks->decommit(chunk, chunksize,
pageind << LG_PAGE, npages << LG_PAGE, arena->ind);
if (decommitted) {
arena_mapbits_large_set(chunk, pageind+npages-1,
0, CHUNK_MAP_DECOMMITTED);
arena_mapbits_large_set(chunk, pageind,
run_size, CHUNK_MAP_DECOMMITTED);
unzeroed = false;
flag_unzeroed = 0;
flags = CHUNK_MAP_DECOMMITTED;
} else {
unzeroed = chunk_purge_wrapper(arena,
flag_unzeroed = chunk_purge_wrapper(arena,
chunk_hooks, chunk, chunksize, pageind <<
LG_PAGE, run_size);
LG_PAGE, run_size) ? CHUNK_MAP_UNZEROED : 0;
flags = flag_unzeroed;
}
flag_unzeroed = unzeroed ? CHUNK_MAP_UNZEROED : 0;
arena_mapbits_large_set(chunk, pageind+npages-1, 0,
flags);
arena_mapbits_large_set(chunk, pageind, run_size,
flags);
/*
* Set the unzeroed flag for all pages, now that
* Set the unzeroed flag for internal pages, now that
* chunk_purge_wrapper() has returned whether the pages
* were zeroed as a side effect of purging. This chunk
* map modification is safe even though the arena mutex
@ -1431,8 +1432,8 @@ arena_purge_stashed(arena_t *arena, chunk_hooks_t *chunk_hooks,
* writes don't perturb the first and last elements'
* CHUNK_MAP_ALLOCATED bits, behavior is well defined.
*/
for (i = 0; i < npages; i++) {
arena_mapbits_unzeroed_set(chunk, pageind+i,
for (i = 1; i < npages-1; i++) {
arena_mapbits_internal_set(chunk, pageind+i,
flag_unzeroed);
}
}

2
src/pages.c
View File

@ -102,7 +102,7 @@ pages_commit_impl(void *addr, size_t size, bool commit)
{
#ifndef _WIN32
if (config_debug) {
if (false &&/*XXX*/ config_debug) {
int prot = commit ? (PROT_READ | PROT_WRITE) : PROT_NONE;
void *result = mmap(addr, size, prot, MAP_PRIVATE | MAP_ANON |
MAP_FIXED, -1, 0);