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add abandoned counter for debug purposes

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daan 2020-09-05 18:17:07 -07:00
parent aec70a04a6
commit f3f8afb580
1 changed files with 17 additions and 1 deletions
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18
src/segment.c
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@ -882,6 +882,10 @@ static mi_decl_cache_align _Atomic(mi_segment_t*) abandoned_visited; // =
// The abandoned page list (tagged as it supports pop) // The abandoned page list (tagged as it supports pop)
static mi_decl_cache_align _Atomic(mi_tagged_segment_t) abandoned; // = NULL 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 // We also maintain a count of current readers of the abandoned list
// in order to prevent resetting/decommitting segment memory if it might // in order to prevent resetting/decommitting segment memory if it might
// still be read. // still be read.
@ -897,6 +901,7 @@ static void mi_abandoned_visited_push(mi_segment_t* segment) {
do { do {
mi_atomic_store_ptr_release(mi_segment_t, &segment->abandoned_next, anext); 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)); } 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. // Move the visited list to the abandoned list.
@ -913,8 +918,13 @@ static bool mi_abandoned_visited_revisit(void)
mi_tagged_segment_t afirst; mi_tagged_segment_t afirst;
mi_tagged_segment_t ts = mi_atomic_load_relaxed(&abandoned); mi_tagged_segment_t ts = mi_atomic_load_relaxed(&abandoned);
if (mi_tagged_segment_ptr(ts)==NULL) { if (mi_tagged_segment_ptr(ts)==NULL) {
uintptr_t count = mi_atomic_load_relaxed(&abandoned_visited_count);
afirst = mi_tagged_segment(first, ts); 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) // find the last element of the visited list: O(n)
@ -927,10 +937,14 @@ static bool mi_abandoned_visited_revisit(void)
// and atomically prepend to the abandoned list // and atomically prepend to the abandoned list
// (no need to increase the readers as we don't access the abandoned segments) // (no need to increase the readers as we don't access the abandoned segments)
mi_tagged_segment_t anext = mi_atomic_load_relaxed(&abandoned); mi_tagged_segment_t anext = mi_atomic_load_relaxed(&abandoned);
uintptr_t count;
do { 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)); mi_atomic_store_ptr_release(mi_segment_t, &last->abandoned_next, mi_tagged_segment_ptr(anext));
afirst = mi_tagged_segment(first, anext); afirst = mi_tagged_segment(first, anext);
} while (!mi_atomic_cas_weak_release(&abandoned, &anext, afirst)); } 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; return true;
} }
@ -946,6 +960,7 @@ 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)); mi_atomic_store_ptr_release(mi_segment_t, &segment->abandoned_next, mi_tagged_segment_ptr(ts));
next = mi_tagged_segment(segment, ts); next = mi_tagged_segment(segment, ts);
} while (!mi_atomic_cas_weak_release(&abandoned, &ts, next)); } 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 // Wait until there are no more pending reads on segments that used to be in the abandoned list
@ -986,6 +1001,7 @@ static mi_segment_t* mi_abandoned_pop(void) {
mi_atomic_decrement_relaxed(&abandoned_readers); // release reader lock mi_atomic_decrement_relaxed(&abandoned_readers); // release reader lock
if (segment != NULL) { if (segment != NULL) {
mi_atomic_store_ptr_release(mi_segment_t, &segment->abandoned_next, NULL); mi_atomic_store_ptr_release(mi_segment_t, &segment->abandoned_next, NULL);
mi_atomic_decrement_relaxed(&abandoned_count);
} }
return segment; return segment;
} }