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wip: initial work on purgable arenas

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This commit is contained in:
Daan Leijen 2023-03-31 20:51:35 -07:00
parent 7cf60deb12
commit 595add5e3d
7 changed files with 65 additions and 42 deletions
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79
src/arena.c
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@ -287,14 +287,15 @@ void* _mi_arena_alloc_aligned(size_t size, size_t alignment, size_t align_offset
if (p != NULL) return p;
// otherwise, try to first eagerly reserve a new arena
size_t eager_reserve = mi_option_get_size(mi_option_arena_reserve);
eager_reserve = _mi_align_up(eager_reserve, MI_ARENA_BLOCK_SIZE);
if (eager_reserve > 0 && eager_reserve >= size && // eager reserve enabled and large enough?
size_t arena_reserve = mi_option_get_size(mi_option_arena_reserve);
arena_reserve = _mi_align_up(arena_reserve, MI_ARENA_BLOCK_SIZE);
if (arena_reserve > 0 && arena_reserve >= size && // eager reserve enabled and large enough?
req_arena_id == _mi_arena_id_none() && // not exclusive?
mi_atomic_load_relaxed(&mi_arena_count) < 3*(MI_MAX_ARENAS/4) ) // not too many arenas already?
{
mi_arena_id_t arena_id = 0;
if (mi_reserve_os_memory_ex(eager_reserve, false /* commit */, *large /* allow large*/, false /* exclusive */, &arena_id) == 0) {
const bool arena_commit = _mi_os_has_overcommit();
if (mi_reserve_os_memory_ex(arena_reserve, arena_commit /* commit */, *large /* allow large*/, false /* exclusive */, &arena_id) == 0) {
p = mi_arena_alloc_in(arena_id, numa_node, size, alignment, commit, large, is_pinned, is_zero, req_arena_id, memid, tld);
if (p != NULL) return p;
}
@ -383,7 +384,7 @@ static void mi_arena_schedule_purge(mi_arena_t* arena, size_t bitmap_idx, size_t
}
}
// return true if the full range was purged
// return true if the full range was purged.
static bool mi_arena_purge_range(mi_arena_t* arena, size_t idx, size_t startidx, size_t bitlen, size_t purge, mi_stats_t* stats) {
const size_t endidx = startidx + bitlen;
size_t bitidx = startidx;
@ -401,12 +402,12 @@ static bool mi_arena_purge_range(mi_arena_t* arena, size_t idx, size_t startidx,
all_purged = true;
}
}
bitidx += (count+1);
bitidx += (count+1); // +1 to skip the zero bit (or end)
}
return all_purged;
}
// returns true if anything was decommitted
// returns true if anything was purged
static bool mi_arena_try_purge(mi_arena_t* arena, mi_msecs_t now, bool force, mi_stats_t* stats)
{
if (!arena->allow_decommit || arena->blocks_purge == NULL) return false;
@ -425,35 +426,33 @@ static bool mi_arena_try_purge(mi_arena_t* arena, mi_msecs_t now, bool force, mi
if (purge != 0) {
size_t bitidx = 0;
while (bitidx < MI_BITMAP_FIELD_BITS) {
size_t bitlen = 1;
if ((purge & ((size_t)1 << bitidx)) != 0) {
while ((bitidx + bitlen < MI_BITMAP_FIELD_BITS) &&
((purge & ((size_t)1 << (bitidx + bitlen))) != 0)) { bitlen++; }
// found range of purgeable blocks
// try to claim the longest range of corresponding in_use bits
const mi_bitmap_index_t bitmap_index = mi_bitmap_index_create(i, bitidx);
while( bitlen > 0 ) {
if (_mi_bitmap_try_claim(arena->blocks_inuse, arena->field_count, bitlen, bitmap_index)) {
break;
}
bitlen--;
}
// claimed count bits at in_use
if (bitlen > 0) {
// read purge again now that we have the in_use bits
purge = mi_atomic_load_acquire(&arena->blocks_purge[i]);
if (!mi_arena_purge_range(arena, i, bitidx, bitlen, purge, stats)) {
full_purge = false;
}
any_purged = true;
}
else {
bitlen = 1; // make progress
}
// find length 1 bit range
size_t bitlen = 0;
while (bitidx + bitlen < MI_BITMAP_FIELD_BITS && (purge & ((size_t)1 << (bitidx + bitlen))) != 0) {
bitlen++;
}
bitidx += bitlen;
}
}
// try to claim the longest range of corresponding in_use bits
const mi_bitmap_index_t bitmap_index = mi_bitmap_index_create(i, bitidx);
while( bitlen > 0 ) {
if (_mi_bitmap_try_claim(arena->blocks_inuse, arena->field_count, bitlen, bitmap_index)) {
break;
}
bitlen--;
}
// claimed count bits at in_use
if (bitlen > 0) {
// read purge again now that we have the in_use bits
purge = mi_atomic_load_acquire(&arena->blocks_purge[i]);
if (!mi_arena_purge_range(arena, i, bitidx, bitlen, purge, stats)) {
full_purge = false;
}
any_purged = true;
// release claimed in_use bits again
_mi_bitmap_unclaim(arena->blocks_inuse, arena->field_count, bitlen, bitmap_index);
}
bitidx += (bitlen+1); // +1 to skip the zero (or end)
} // while bitidx
} // purge != 0
}
return any_purged;
}
@ -532,9 +531,17 @@ void _mi_arena_free(void* p, size_t size, size_t alignment, size_t align_offset,
return;
};
}
// purge expired decommits
mi_arenas_try_purge(false, false, stats);
}
void _mi_arena_collect(bool free_arenas, bool force_decommit, mi_stats_t* stats) {
MI_UNUSED(free_arenas); // todo
mi_arenas_try_purge(force_decommit, true, stats);
}
/* -----------------------------------------------------------
Add an arena.
----------------------------------------------------------- */
@ -566,7 +573,7 @@ bool mi_manage_os_memory_ex(void* start, size_t size, bool is_committed, bool is
is_committed = true;
}
const bool allow_decommit = !is_large && !is_committed; // only allow decommit for initially uncommitted memory
const bool allow_decommit = !is_large; // && !is_committed; // only allow decommit for initially uncommitted memory
const size_t bcount = size / MI_ARENA_BLOCK_SIZE;
const size_t fields = _mi_divide_up(bcount, MI_BITMAP_FIELD_BITS);