truffle: src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp comparison

comparison src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp @ 636:6c4cea9bfa11

6604422: G1: re-use half-promoted regions 6728271: G1: Cleanup G1CollectedHeap::get_gc_alloc_regions() Summary: It allows the last half-full region to be allocated to during a GC to be reused during the next GC. Reviewed-by: apetrusenko, jcoomes

author	tonyp
date	Sun, 15 Mar 2009 22:03:38 -0400
parents	87fa6e083d82
children	25e146966e7c

comparison

equal deleted inserted replaced

-:fe2441500281
+:6c4cea9bfa11
 }
 _cur_alloc_region = NULL;
 }
 }
+void G1CollectedHeap::abandon_gc_alloc_regions() {
+// first, make sure that the GC alloc region list is empty (it should!)
+assert(_gc_alloc_region_list == NULL, "invariant");
+release_gc_alloc_regions(true /* totally */);
+}
 class PostMCRemSetClearClosure: public HeapRegionClosure {
 ModRefBarrierSet* _mr_bs;
 public:
 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
 bool doHeapRegion(HeapRegion* r) {
 // refinement, if any are in progress.
 concurrent_mark()->abort();
 // Make sure we'll choose a new allocation region afterwards.
 abandon_cur_alloc_region();
+abandon_gc_alloc_regions();
 assert(_cur_alloc_region == NULL, "Invariant.");
 g1_rem_set()->as_HRInto_G1RemSet()->cleanupHRRS();
 tear_down_region_lists();
 set_used_regions_to_need_zero_fill();
 if (g1_policy()->in_young_gc_mode()) {
 new_mem_size/K);
 }
 }
 void G1CollectedHeap::shrink(size_t shrink_bytes) {
-release_gc_alloc_regions();
+release_gc_alloc_regions(true /* totally */);
 tear_down_region_lists();  // We will rebuild them in a moment.
 shrink_helper(shrink_bytes);
 rebuild_region_lists();
 }
 _unclean_regions_coming(false),
 _young_list(new YoungList(this)),
 _gc_time_stamp(0),
 _surviving_young_words(NULL),
 _in_cset_fast_test(NULL),
-_in_cset_fast_test_base(NULL)
+_in_cset_fast_test_base(NULL) {
-{
 _g1h = this; // To catch bugs.
 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
 vm_exit_during_initialization("Failed necessary allocation.");
 }
 int n_queues = MAX2((int)ParallelGCThreads, 1);
 q->initialize();
 _task_queues->register_queue(i, q);
 }
 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
-_gc_alloc_regions[ap]       = NULL;
+_gc_alloc_regions[ap]          = NULL;
-_gc_alloc_region_counts[ap] = 0;
+_gc_alloc_region_counts[ap]    = 0;
-}
+_retained_gc_alloc_regions[ap] = NULL;
+// by default, we do not retain a GC alloc region for each ap;
+// we'll override this, when appropriate, below
+_retain_gc_alloc_region[ap]    = false;
+}
+// We will try to remember the last half-full tenured region we
+// allocated to at the end of a collection so that we can re-use it
+// during the next collection.
+_retain_gc_alloc_region[GCAllocForTenured]  = true;
 guarantee(_task_queues != NULL, "task_queues allocation failure.");
 }
 jint G1CollectedHeap::initialize() {
 os::enable_vtime();
 // We have to wait until now, because we don't want the region to
 // be rescheduled for pop-evac during RS update.
 popular_region->set_popular_pending(false);
 }
-release_gc_alloc_regions();
+release_gc_alloc_regions(false /* totally */);
 cleanup_surviving_young_words();
 if (g1_policy()->in_young_gc_mode()) {
 _young_list->reset_sampled_info();
 }
 }
 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
+// make sure we don't call set_gc_alloc_region() multiple times on
+// the same region
+assert(r == NULL || !r->is_gc_alloc_region(),
+"shouldn't already be a GC alloc region");
 HeapWord* original_top = NULL;
 if (r != NULL)
 original_top = r->top();
 // We will want to record the used space in r as being there before gc.
 // TODO: allocation regions check
 return true;
 }
 void G1CollectedHeap::get_gc_alloc_regions() {
+// First, let's check that the GC alloc region list is empty (it should)
+assert(_gc_alloc_region_list == NULL, "invariant");
 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
+assert(_gc_alloc_regions[ap] == NULL, "invariant");
 // Create new GC alloc regions.
-HeapRegion* alloc_region = _gc_alloc_regions[ap];
+HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
-// Clear this alloc region, so that in case it turns out to be
+_retained_gc_alloc_regions[ap] = NULL;
-// unacceptable, we end up with no allocation region, rather than a bad
-// one.
+if (alloc_region != NULL) {
-_gc_alloc_regions[ap] = NULL;
+assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
-if (alloc_region == NULL || alloc_region->in_collection_set()) {
-// Can't re-use old one.  Allocate a new one.
+// let's make sure that the GC alloc region is not tagged as such
+// outside a GC operation
+assert(!alloc_region->is_gc_alloc_region(), "sanity");
+if (alloc_region->in_collection_set() ||
+alloc_region->top() == alloc_region->end() ||
+alloc_region->top() == alloc_region->bottom()) {
+// we will discard the current GC alloc region if it's in the
+// collection set (it can happen!), if it's already full (no
+// point in using it), or if it's empty (this means that it
+// was emptied during a cleanup and it should be on the free
+// list now).
+alloc_region = NULL;
+}
+}
+if (alloc_region == NULL) {
+// we will get a new GC alloc region
 alloc_region = newAllocRegionWithExpansion(ap, 0);
 }
 if (alloc_region != NULL) {
+assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
 set_gc_alloc_region(ap, alloc_region);
 }
+assert(_gc_alloc_regions[ap] == NULL ||
+_gc_alloc_regions[ap]->is_gc_alloc_region(),
+"the GC alloc region should be tagged as such");
+assert(_gc_alloc_regions[ap] == NULL ||
+_gc_alloc_regions[ap] == _gc_alloc_region_list,
+"the GC alloc region should be the same as the GC alloc list head");
 }
 // Set alternative regions for allocation purposes that have reached
-// thier limit.
+// their limit.
 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
 }
 }
 assert(check_gc_alloc_regions(), "alloc regions messed up");
 }
-void G1CollectedHeap::release_gc_alloc_regions() {
+void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
 // We keep a separate list of all regions that have been alloc regions in
-// the current collection pause.  Forget that now.
+// the current collection pause. Forget that now. This method will
+// untag the GC alloc regions and tear down the GC alloc region
+// list. It's desirable that no regions are tagged as GC alloc
+// outside GCs.
 forget_alloc_region_list();
 // The current alloc regions contain objs that have survived
 // collection. Make them no longer GC alloc regions.
 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
 HeapRegion* r = _gc_alloc_regions[ap];
-if (r != NULL && r->is_empty()) {
+_retained_gc_alloc_regions[ap] = NULL;
-{
+if (r != NULL) {
+// we retain nothing on _gc_alloc_regions between GCs
+set_gc_alloc_region(ap, NULL);
+_gc_alloc_region_counts[ap] = 0;
+if (r->is_empty()) {
+// we didn't actually allocate anything in it; let's just put
+// it on the free list
 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
 r->set_zero_fill_complete();
 put_free_region_on_list_locked(r);
+} else if (_retain_gc_alloc_region[ap] && !totally) {
+// retain it so that we can use it at the beginning of the next GC
+_retained_gc_alloc_regions[ap] = r;
 }
 }
-// set_gc_alloc_region will also NULLify all aliases to the region
+}
-set_gc_alloc_region(ap, NULL);
+}
-_gc_alloc_region_counts[ap] = 0;
-}
+#ifndef PRODUCT
-}
+// Useful for debugging
+void G1CollectedHeap::print_gc_alloc_regions() {
+gclog_or_tty->print_cr("GC alloc regions");
+for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
+HeapRegion* r = _gc_alloc_regions[ap];
+if (r == NULL) {
+gclog_or_tty->print_cr("  %2d : "PTR_FORMAT, ap, NULL);
+} else {
+gclog_or_tty->print_cr("  %2d : "PTR_FORMAT" "SIZE_FORMAT,
+ap, r->bottom(), r->used());
+}
+}
+}
+#endif // PRODUCT
 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
 _drain_in_progress = false;
 set_evac_failure_closure(cl);
 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);

Mercurial > hg > truffle

comparison src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp @ 636:6c4cea9bfa11