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atomically clear purge bits when visiting

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daanx 2024-12-17 12:32:18 -08:00
parent c585753dce
commit 34d03f3981
3 changed files with 20 additions and 22 deletions
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33
src/arena.c
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@ -1392,19 +1392,21 @@ static long mi_arena_purge_delay(void) {
// reset or decommit in an arena and update the commit bitmap
// assumes we own the area (i.e. slices_free is claimed by us)
static void mi_arena_purge(mi_arena_t* arena, size_t slice_index, size_t slice_count) {
// returns if the memory is no longer committed (versus reset which keeps the commit)
static bool mi_arena_purge(mi_arena_t* arena, size_t slice_index, size_t slice_count) {
mi_assert_internal(!arena->memid.is_pinned);
mi_assert_internal(mi_bitmap_is_clearN(arena->slices_free, slice_index, slice_count));
const size_t size = mi_size_of_slices(slice_count);
void* const p = mi_arena_slice_start(arena, slice_index);
const bool all_committed = mi_bitmap_is_setN(arena->slices_committed, slice_index, slice_count);
const bool needs_recommit = _mi_os_purge_ex(p, size, all_committed);
const bool needs_recommit = _mi_os_purge_ex(p, size, all_committed /* allow reset? */);
// update committed bitmap
if (needs_recommit) {
mi_bitmap_clearN(arena->slices_committed, slice_index, slice_count);
}
return needs_recommit;
}
@ -1421,12 +1423,13 @@ static void mi_arena_schedule_purge(mi_arena_t* arena, size_t slice_index, size_
}
else {
// schedule purge
mi_msecs_t expire = mi_atomic_loadi64_relaxed(&arena->purge_expire);
if (expire == 0) {
mi_atomic_storei64_release(&arena->purge_expire, _mi_clock_now() + delay);
mi_msecs_t expire0 = 0;
if (mi_atomic_casi64_strong_acq_rel(&arena->purge_expire, &expire0, _mi_clock_now() + delay)) {
// expiration was not yet set
mi_atomic_storei64_release(&arena->purge_expire_extend, 0);
}
else if (mi_atomic_loadi64_acquire(&arena->purge_expire_extend) < 10*delay) { // limit max extension time
// already an expiration was set
mi_atomic_addi64_acq_rel(&arena->purge_expire_extend, (mi_msecs_t)(delay/10)); // add smallish extra delay
}
mi_bitmap_setN(arena->slices_purge, slice_index, slice_count, NULL);
@ -1443,8 +1446,8 @@ typedef struct mi_purge_visit_info_s {
static bool mi_arena_try_purge_range(mi_arena_t* arena, size_t slice_index, size_t slice_count) {
if (mi_bitmap_try_clearN(arena->slices_free, slice_index, slice_count)) {
// purge
mi_arena_purge(arena, slice_index, slice_count);
mi_assert_internal(mi_bitmap_is_clearN(arena->slices_committed, slice_index, slice_count));
bool decommitted = mi_arena_purge(arena, slice_index, slice_count); MI_UNUSED(decommitted);
mi_assert_internal(!decommitted || mi_bitmap_is_clearN(arena->slices_committed, slice_index, slice_count));
// and reset the free range
mi_bitmap_setN(arena->slices_free, slice_index, slice_count, NULL);
return true;
@ -1470,8 +1473,8 @@ static bool mi_arena_try_purge_visitor(size_t slice_index, size_t slice_count, m
vinfo->all_purged = vinfo->all_purged && purged;
}
}
// done: clear the purge bits
mi_bitmap_clearN(arena->slices_purge, slice_index, slice_count);
// don't clear the purge bits as that is done atomically be the _bitmap_forall_set_ranges
// mi_bitmap_clearN(arena->slices_purge, slice_index, slice_count);
return true; // continue
}
@ -1495,17 +1498,11 @@ static bool mi_arena_try_purge(mi_arena_t* arena, mi_msecs_t now, bool force)
_mi_stat_counter_increase(&_mi_stats_main.arena_purges, 1);
// go through all purge info's (with max MI_BFIELD_BITS ranges at a time)
// this also clears those ranges atomically (so any newly freed blocks will get purged next
// time around)
mi_purge_visit_info_t vinfo = { now, mi_arena_purge_delay(), true /*all?*/, false /*any?*/};
_mi_bitmap_forall_set_ranges(arena->slices_purge, &mi_arena_try_purge_visitor, arena, &vinfo);
_mi_bitmap_forall_setc_ranges(arena->slices_purge, &mi_arena_try_purge_visitor, arena, &vinfo);
// if not fully purged, make sure to purge again in the future
if (!vinfo.all_purged) {
const long delay = mi_arena_purge_delay();
mi_msecs_t expected = 0;
if (mi_atomic_casi64_strong_acq_rel(&arena->purge_expire, &expected, _mi_clock_now() + delay)) {
mi_atomic_storei64_release(&arena->purge_expire_extend, (mi_msecs_t)0);
}
}
return vinfo.any_purged;
}