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Merge branch 'dev' into dev-slice

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This commit is contained in:
daan 2020-09-05 18:17:22 -07:00
commit 36da7e91c5
5 changed files with 49 additions and 30 deletions
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18
src/segment.c
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@ -897,6 +897,10 @@ static mi_decl_cache_align _Atomic(mi_segment_t*) abandoned_visited; // =
// The abandoned page list (tagged as it supports pop)
static mi_decl_cache_align _Atomic(mi_tagged_segment_t) abandoned; // = NULL
// Maintain these for debug purposes (these counts may be a bit off)
static mi_decl_cache_align _Atomic(uintptr_t) abandoned_count;
static mi_decl_cache_align _Atomic(uintptr_t) abandoned_visited_count;
// We also maintain a count of current readers of the abandoned list
// in order to prevent resetting/decommitting segment memory if it might
// still be read.
@ -912,6 +916,7 @@ static void mi_abandoned_visited_push(mi_segment_t* segment) {
do {
mi_atomic_store_ptr_release(mi_segment_t, &segment->abandoned_next, anext);
} while (!mi_atomic_cas_ptr_weak_release(mi_segment_t, &abandoned_visited, &anext, segment));
mi_atomic_increment_relaxed(&abandoned_visited_count);
}
// Move the visited list to the abandoned list.
@ -928,8 +933,13 @@ static bool mi_abandoned_visited_revisit(void)
mi_tagged_segment_t afirst;
mi_tagged_segment_t ts = mi_atomic_load_relaxed(&abandoned);
if (mi_tagged_segment_ptr(ts)==NULL) {
uintptr_t count = mi_atomic_load_relaxed(&abandoned_visited_count);
afirst = mi_tagged_segment(first, ts);
if (mi_atomic_cas_strong_acq_rel(&abandoned, &ts, afirst)) return true;
if (mi_atomic_cas_strong_acq_rel(&abandoned, &ts, afirst)) {
mi_atomic_add_relaxed(&abandoned_count, count);
mi_atomic_sub_relaxed(&abandoned_visited_count, count);
return true;
}
}
// find the last element of the visited list: O(n)
@ -942,10 +952,14 @@ static bool mi_abandoned_visited_revisit(void)
// and atomically prepend to the abandoned list
// (no need to increase the readers as we don't access the abandoned segments)
mi_tagged_segment_t anext = mi_atomic_load_relaxed(&abandoned);
uintptr_t count;
do {
count = mi_atomic_load_relaxed(&abandoned_visited_count);
mi_atomic_store_ptr_release(mi_segment_t, &last->abandoned_next, mi_tagged_segment_ptr(anext));
afirst = mi_tagged_segment(first, anext);
} while (!mi_atomic_cas_weak_release(&abandoned, &anext, afirst));
mi_atomic_add_relaxed(&abandoned_count, count);
mi_atomic_sub_relaxed(&abandoned_visited_count, count);
return true;
}
@ -961,6 +975,7 @@ static void mi_abandoned_push(mi_segment_t* segment) {
mi_atomic_store_ptr_release(mi_segment_t, &segment->abandoned_next, mi_tagged_segment_ptr(ts));
next = mi_tagged_segment(segment, ts);
} while (!mi_atomic_cas_weak_release(&abandoned, &ts, next));
mi_atomic_increment_relaxed(&abandoned_count);
}
// Wait until there are no more pending reads on segments that used to be in the abandoned list
@ -1002,6 +1017,7 @@ static mi_segment_t* mi_abandoned_pop(void) {
mi_atomic_decrement_relaxed(&abandoned_readers); // release reader lock
if (segment != NULL) {
mi_atomic_store_ptr_release(mi_segment_t, &segment->abandoned_next, NULL);
mi_atomic_decrement_relaxed(&abandoned_count);
}
return segment;
}