--- a/src/hotspot/share/gc/g1/collectionSetChooser.hpp Fri Feb 08 12:55:20 2019 +0100
+++ b/src/hotspot/share/gc/g1/collectionSetChooser.hpp Fri Feb 08 12:55:20 2019 +0100
@@ -26,177 +26,35 @@
#define SHARE_GC_G1_COLLECTIONSETCHOOSER_HPP
#include "gc/g1/heapRegion.hpp"
-#include "utilities/growableArray.hpp"
-
-class CollectionSetChooser: public CHeapObj<mtGC> {
-
- GrowableArray<HeapRegion*> _regions;
-
- // Unfortunately, GrowableArray uses ints for length and indexes. To
- // avoid excessive casting in the rest of the class the following
- // wrapper methods are provided that use uints.
+#include "memory/allocation.hpp"
+#include "runtime/globals.hpp"
- uint regions_length() { return (uint) _regions.length(); }
- HeapRegion* regions_at(uint i) { return _regions.at((int) i); }
- void regions_at_put(uint i, HeapRegion* hr) {
- _regions.at_put((int) i, hr);
- }
- void regions_at_put_grow(uint i, HeapRegion* hr) {
- _regions.at_put_grow((int) i, hr);
- }
- void regions_trunc_to(uint i) { _regions.trunc_to((uint) i); }
-
- // The index of the next candidate old region to be considered for
- // addition to the CSet.
- uint _front;
-
- // The index of the last candidate old region
- uint _end;
-
- // Keeps track of the start of the next array chunk to be claimed by
- // parallel GC workers.
- uint _first_par_unreserved_idx;
-
- // If a region has more live bytes than this threshold, it will not
- // be added to the CSet chooser and will not be a candidate for
- // collection.
- size_t _region_live_threshold_bytes;
+class G1CollectionSetCandidates;
+class WorkGang;
- // The sum of reclaimable bytes over all the regions in the CSet chooser.
- size_t _remaining_reclaimable_bytes;
-
- // Calculate and return chunk size (in number of regions) for parallel
- // addition of regions
- uint calculate_parallel_work_chunk_size(uint n_workers, uint n_regions) const;
+// Helper class to calculate collection set candidates, and containing some related
+// methods.
+class CollectionSetChooser : public AllStatic {
+ static uint calculate_work_chunk_size(uint num_workers, uint num_regions);
public:
- // Return the current candidate region to be considered for
- // collection without removing it from the CSet chooser.
- HeapRegion* peek() {
- HeapRegion* res = NULL;
- if (_front < _end) {
- res = regions_at(_front);
- assert(res != NULL, "Unexpected NULL hr in _regions at index %u", _front);
- }
- return res;
- }
-
- // Remove the given region from the CSet chooser and move to the
- // next one.
- HeapRegion* pop() {
- HeapRegion* hr = regions_at(_front);
- assert(hr != NULL, "pre-condition");
- assert(_front < _end, "pre-condition");
- regions_at_put(_front, NULL);
- assert(hr->reclaimable_bytes() <= _remaining_reclaimable_bytes,
- "remaining reclaimable bytes inconsistent "
- "from region: " SIZE_FORMAT " remaining: " SIZE_FORMAT,
- hr->reclaimable_bytes(), _remaining_reclaimable_bytes);
- _remaining_reclaimable_bytes -= hr->reclaimable_bytes();
- _front += 1;
- return hr;
- }
-
- void push(HeapRegion* hr);
-
- CollectionSetChooser();
-
static size_t mixed_gc_live_threshold_bytes() {
return HeapRegion::GrainBytes * (size_t) G1MixedGCLiveThresholdPercent / 100;
}
- static bool region_occupancy_low_enough_for_evac(size_t live_bytes);
+ static bool region_occupancy_low_enough_for_evac(size_t live_bytes) {
+ return live_bytes < mixed_gc_live_threshold_bytes();
+ }
- void sort_regions();
-
- // Determine whether to add the given region to the CSet chooser or
+ // Determine whether to add the given region to the collection set candidates or
// not. Currently, we skip pinned regions and regions whose live
// bytes are over the threshold. Humongous regions may be reclaimed during cleanup.
// Regions also need a complete remembered set to be a candidate.
- bool should_add(HeapRegion* hr) const;
-
- // Returns the number candidate old regions added
- uint length() { return _end; }
-
- // Serial version.
- void add_region(HeapRegion *hr);
-
- // Must be called before calls to claim_array_chunk().
- // n_regions is the number of regions, chunk_size the chunk size.
- void prepare_for_par_region_addition(uint n_threads, uint n_regions, uint chunk_size);
- // Returns the first index in a contiguous chunk of chunk_size indexes
- // that the calling thread has reserved. These must be set by the
- // calling thread using set_region() (to NULL if necessary).
- uint claim_array_chunk(uint chunk_size);
- // Set the marked array entry at index to hr. Careful to claim the index
- // first if in parallel.
- void set_region(uint index, HeapRegion* hr);
- // Atomically increment the number of added regions by region_num
- // and the amount of reclaimable bytes by reclaimable_bytes.
- void update_totals(uint region_num, size_t reclaimable_bytes);
-
- // Iterate over all collection set candidate regions.
- void iterate(HeapRegionClosure* cl);
-
- void clear();
-
- void rebuild(WorkGang* workers, uint n_regions);
-
- // Return the number of candidate regions that remain to be collected.
- uint remaining_regions() { return _end - _front; }
-
- // Determine whether the CSet chooser has more candidate regions or not.
- bool is_empty() { return remaining_regions() == 0; }
-
- // Return the reclaimable bytes that remain to be collected on
- // all the candidate regions in the CSet chooser.
- size_t remaining_reclaimable_bytes() { return _remaining_reclaimable_bytes; }
+ static bool should_add(HeapRegion* hr);
- // Returns true if the used portion of "_regions" is properly
- // sorted, otherwise asserts false.
- void verify() PRODUCT_RETURN;
-};
-
-class CSetChooserParUpdater : public StackObj {
-private:
- CollectionSetChooser* _chooser;
- bool _parallel;
- uint _chunk_size;
- uint _cur_chunk_idx;
- uint _cur_chunk_end;
- uint _regions_added;
- size_t _reclaimable_bytes_added;
-
-public:
- CSetChooserParUpdater(CollectionSetChooser* chooser,
- bool parallel, uint chunk_size) :
- _chooser(chooser), _parallel(parallel), _chunk_size(chunk_size),
- _cur_chunk_idx(0), _cur_chunk_end(0),
- _regions_added(0), _reclaimable_bytes_added(0) { }
-
- ~CSetChooserParUpdater() {
- if (_parallel && _regions_added > 0) {
- _chooser->update_totals(_regions_added, _reclaimable_bytes_added);
- }
- }
-
- void add_region(HeapRegion* hr) {
- if (_parallel) {
- if (_cur_chunk_idx == _cur_chunk_end) {
- _cur_chunk_idx = _chooser->claim_array_chunk(_chunk_size);
- _cur_chunk_end = _cur_chunk_idx + _chunk_size;
- }
- assert(_cur_chunk_idx < _cur_chunk_end, "invariant");
- _chooser->set_region(_cur_chunk_idx, hr);
- _cur_chunk_idx += 1;
- } else {
- _chooser->add_region(hr);
- }
- _regions_added += 1;
- _reclaimable_bytes_added += hr->reclaimable_bytes();
- }
-
- bool should_add(HeapRegion* hr) { return _chooser->should_add(hr); }
+ // Build and return set of collection set candidates sorted by decreasing gc
+ // efficiency.
+ static G1CollectionSetCandidates* build(WorkGang* workers, uint max_num_regions);
};
#endif // SHARE_GC_G1_COLLECTIONSETCHOOSER_HPP