--- a/hotspot/src/share/vm/gc_implementation/g1/collectionSetChooser.cpp Wed Jan 18 09:50:16 2012 -0800
+++ b/hotspot/src/share/vm/gc_implementation/g1/collectionSetChooser.cpp Wed Feb 15 13:06:53 2012 -0500
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -48,6 +48,8 @@
#ifndef PRODUCT
bool CSetChooserCache::verify() {
+ guarantee(false, "CSetChooserCache::verify(): don't call this any more");
+
int index = _first;
HeapRegion *prev = NULL;
for (int i = 0; i < _occupancy; ++i) {
@@ -75,6 +77,8 @@
#endif // PRODUCT
void CSetChooserCache::insert(HeapRegion *hr) {
+ guarantee(false, "CSetChooserCache::insert(): don't call this any more");
+
assert(!is_full(), "cache should not be empty");
hr->calc_gc_efficiency();
@@ -104,6 +108,9 @@
}
HeapRegion *CSetChooserCache::remove_first() {
+ guarantee(false, "CSetChooserCache::remove_first(): "
+ "don't call this any more");
+
if (_occupancy > 0) {
assert(_cache[_first] != NULL, "cache should have at least one region");
HeapRegion *ret = _cache[_first];
@@ -118,16 +125,35 @@
}
}
-static inline int orderRegions(HeapRegion* hr1, HeapRegion* hr2) {
+// Even though we don't use the GC efficiency in our heuristics as
+// much as we used to, we still order according to GC efficiency. This
+// will cause regions with a lot of live objects and large RSets to
+// end up at the end of the array. Given that we might skip collecting
+// the last few old regions, if after a few mixed GCs the remaining
+// have reclaimable bytes under a certain threshold, the hope is that
+// the ones we'll skip are ones with both large RSets and a lot of
+// live objects, not the ones with just a lot of live objects if we
+// ordered according to the amount of reclaimable bytes per region.
+static int orderRegions(HeapRegion* hr1, HeapRegion* hr2) {
if (hr1 == NULL) {
- if (hr2 == NULL) return 0;
- else return 1;
+ if (hr2 == NULL) {
+ return 0;
+ } else {
+ return 1;
+ }
} else if (hr2 == NULL) {
return -1;
}
- if (hr2->gc_efficiency() < hr1->gc_efficiency()) return -1;
- else if (hr1->gc_efficiency() < hr2->gc_efficiency()) return 1;
- else return 0;
+
+ double gc_eff1 = hr1->gc_efficiency();
+ double gc_eff2 = hr2->gc_efficiency();
+ if (gc_eff1 > gc_eff2) {
+ return -1;
+ } if (gc_eff1 < gc_eff2) {
+ return 1;
+ } else {
+ return 0;
+ }
}
static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {
@@ -151,51 +177,61 @@
//
_markedRegions((ResourceObj::set_allocation_type((address)&_markedRegions,
ResourceObj::C_HEAP),
- 100),
- true),
- _curMarkedIndex(0),
- _numMarkedRegions(0),
- _unmarked_age_1_returned_as_new(false),
- _first_par_unreserved_idx(0)
-{}
-
-
+ 100), true /* C_Heap */),
+ _curr_index(0), _length(0),
+ _regionLiveThresholdBytes(0), _remainingReclaimableBytes(0),
+ _first_par_unreserved_idx(0) {
+ _regionLiveThresholdBytes =
+ HeapRegion::GrainBytes * (size_t) G1OldCSetRegionLiveThresholdPercent / 100;
+}
#ifndef PRODUCT
bool CollectionSetChooser::verify() {
+ guarantee(_length >= 0, err_msg("_length: %d", _length));
+ guarantee(0 <= _curr_index && _curr_index <= _length,
+ err_msg("_curr_index: %d _length: %d", _curr_index, _length));
int index = 0;
- guarantee(_curMarkedIndex <= _numMarkedRegions,
- "_curMarkedIndex should be within bounds");
- while (index < _curMarkedIndex) {
- guarantee(_markedRegions.at(index++) == NULL,
- "all entries before _curMarkedIndex should be NULL");
+ size_t sum_of_reclaimable_bytes = 0;
+ while (index < _curr_index) {
+ guarantee(_markedRegions.at(index) == NULL,
+ "all entries before _curr_index should be NULL");
+ index += 1;
}
HeapRegion *prev = NULL;
- while (index < _numMarkedRegions) {
+ while (index < _length) {
HeapRegion *curr = _markedRegions.at(index++);
guarantee(curr != NULL, "Regions in _markedRegions array cannot be NULL");
int si = curr->sort_index();
guarantee(!curr->is_young(), "should not be young!");
+ guarantee(!curr->isHumongous(), "should not be humongous!");
guarantee(si > -1 && si == (index-1), "sort index invariant");
if (prev != NULL) {
- guarantee(orderRegions(prev, curr) != 1, "regions should be sorted");
+ guarantee(orderRegions(prev, curr) != 1,
+ err_msg("GC eff prev: %1.4f GC eff curr: %1.4f",
+ prev->gc_efficiency(), curr->gc_efficiency()));
}
+ sum_of_reclaimable_bytes += curr->reclaimable_bytes();
prev = curr;
}
- return _cache.verify();
+ guarantee(sum_of_reclaimable_bytes == _remainingReclaimableBytes,
+ err_msg("reclaimable bytes inconsistent, "
+ "remaining: "SIZE_FORMAT" sum: "SIZE_FORMAT,
+ _remainingReclaimableBytes, sum_of_reclaimable_bytes));
+ return true;
}
#endif
-void
-CollectionSetChooser::fillCache() {
- while (!_cache.is_full() && (_curMarkedIndex < _numMarkedRegions)) {
- HeapRegion* hr = _markedRegions.at(_curMarkedIndex);
+void CollectionSetChooser::fillCache() {
+ guarantee(false, "fillCache: don't call this any more");
+
+ while (!_cache.is_full() && (_curr_index < _length)) {
+ HeapRegion* hr = _markedRegions.at(_curr_index);
assert(hr != NULL,
err_msg("Unexpected NULL hr in _markedRegions at index %d",
- _curMarkedIndex));
- _curMarkedIndex += 1;
+ _curr_index));
+ _curr_index += 1;
assert(!hr->is_young(), "should not be young!");
- assert(hr->sort_index() == _curMarkedIndex-1, "sort_index invariant");
+ assert(hr->sort_index() == _curr_index-1, "sort_index invariant");
_markedRegions.at_put(hr->sort_index(), NULL);
_cache.insert(hr);
assert(!_cache.is_empty(), "cache should not be empty");
@@ -203,9 +239,7 @@
assert(verify(), "cache should be consistent");
}
-void
-CollectionSetChooser::sortMarkedHeapRegions() {
- guarantee(_cache.is_empty(), "cache should be empty");
+void CollectionSetChooser::sortMarkedHeapRegions() {
// First trim any unused portion of the top in the parallel case.
if (_first_par_unreserved_idx > 0) {
if (G1PrintParCleanupStats) {
@@ -217,43 +251,78 @@
_markedRegions.trunc_to(_first_par_unreserved_idx);
}
_markedRegions.sort(orderRegions);
- assert(_numMarkedRegions <= _markedRegions.length(), "Requirement");
- assert(_numMarkedRegions == 0
- || _markedRegions.at(_numMarkedRegions-1) != NULL,
- "Testing _numMarkedRegions");
- assert(_numMarkedRegions == _markedRegions.length()
- || _markedRegions.at(_numMarkedRegions) == NULL,
- "Testing _numMarkedRegions");
+ assert(_length <= _markedRegions.length(), "Requirement");
+ assert(_length == 0 || _markedRegions.at(_length - 1) != NULL,
+ "Testing _length");
+ assert(_length == _markedRegions.length() ||
+ _markedRegions.at(_length) == NULL, "Testing _length");
if (G1PrintParCleanupStats) {
- gclog_or_tty->print_cr(" Sorted %d marked regions.", _numMarkedRegions);
+ gclog_or_tty->print_cr(" Sorted %d marked regions.", _length);
}
- for (int i = 0; i < _numMarkedRegions; i++) {
+ for (int i = 0; i < _length; i++) {
assert(_markedRegions.at(i) != NULL, "Should be true by sorting!");
_markedRegions.at(i)->set_sort_index(i);
}
if (G1PrintRegionLivenessInfo) {
G1PrintRegionLivenessInfoClosure cl(gclog_or_tty, "Post-Sorting");
- for (int i = 0; i < _numMarkedRegions; ++i) {
+ for (int i = 0; i < _length; ++i) {
HeapRegion* r = _markedRegions.at(i);
cl.doHeapRegion(r);
}
}
- assert(verify(), "should now be sorted");
+ assert(verify(), "CSet chooser verification");
}
-void
-CollectionSetChooser::addMarkedHeapRegion(HeapRegion* hr) {
+size_t CollectionSetChooser::calcMinOldCSetLength() {
+ // The min old CSet region bound is based on the maximum desired
+ // number of mixed GCs after a cycle. I.e., even if some old regions
+ // look expensive, we should add them to the CSet anyway to make
+ // sure we go through the available old regions in no more than the
+ // maximum desired number of mixed GCs.
+ //
+ // The calculation is based on the number of marked regions we added
+ // to the CSet chooser in the first place, not how many remain, so
+ // that the result is the same during all mixed GCs that follow a cycle.
+
+ const size_t region_num = (size_t) _length;
+ const size_t gc_num = (size_t) G1MaxMixedGCNum;
+ size_t result = region_num / gc_num;
+ // emulate ceiling
+ if (result * gc_num < region_num) {
+ result += 1;
+ }
+ return result;
+}
+
+size_t CollectionSetChooser::calcMaxOldCSetLength() {
+ // The max old CSet region bound is based on the threshold expressed
+ // as a percentage of the heap size. I.e., it should bound the
+ // number of old regions added to the CSet irrespective of how many
+ // of them are available.
+
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+ const size_t region_num = g1h->n_regions();
+ const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
+ size_t result = region_num * perc / 100;
+ // emulate ceiling
+ if (100 * result < region_num * perc) {
+ result += 1;
+ }
+ return result;
+}
+
+void CollectionSetChooser::addMarkedHeapRegion(HeapRegion* hr) {
assert(!hr->isHumongous(),
"Humongous regions shouldn't be added to the collection set");
assert(!hr->is_young(), "should not be young!");
_markedRegions.append(hr);
- _numMarkedRegions++;
+ _length++;
+ _remainingReclaimableBytes += hr->reclaimable_bytes();
hr->calc_gc_efficiency();
}
-void
-CollectionSetChooser::
-prepareForAddMarkedHeapRegionsPar(size_t n_regions, size_t chunkSize) {
+void CollectionSetChooser::prepareForAddMarkedHeapRegionsPar(size_t n_regions,
+ size_t chunkSize) {
_first_par_unreserved_idx = 0;
int n_threads = ParallelGCThreads;
if (UseDynamicNumberOfGCThreads) {
@@ -274,8 +343,7 @@
_markedRegions.at_put_grow((int)(aligned_n_regions + max_waste - 1), NULL);
}
-jint
-CollectionSetChooser::getParMarkedHeapRegionChunk(jint n_regions) {
+jint CollectionSetChooser::getParMarkedHeapRegionChunk(jint n_regions) {
// Don't do this assert because this can be called at a point
// where the loop up stream will not execute again but might
// try to claim more chunks (loop test has not been done yet).
@@ -287,83 +355,37 @@
return res - n_regions;
}
-void
-CollectionSetChooser::setMarkedHeapRegion(jint index, HeapRegion* hr) {
+void CollectionSetChooser::setMarkedHeapRegion(jint index, HeapRegion* hr) {
assert(_markedRegions.at(index) == NULL, "precondition");
assert(!hr->is_young(), "should not be young!");
_markedRegions.at_put(index, hr);
hr->calc_gc_efficiency();
}
-void
-CollectionSetChooser::incNumMarkedHeapRegions(jint inc_by) {
- (void)Atomic::add(inc_by, &_numMarkedRegions);
-}
-
-void
-CollectionSetChooser::clearMarkedHeapRegions(){
- for (int i = 0; i < _markedRegions.length(); i++) {
- HeapRegion* r = _markedRegions.at(i);
- if (r != NULL) r->set_sort_index(-1);
+void CollectionSetChooser::updateTotals(jint region_num,
+ size_t reclaimable_bytes) {
+ // Only take the lock if we actually need to update the totals.
+ if (region_num > 0) {
+ assert(reclaimable_bytes > 0, "invariant");
+ // We could have just used atomics instead of taking the
+ // lock. However, we currently don't have an atomic add for size_t.
+ MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
+ _length += (int) region_num;
+ _remainingReclaimableBytes += reclaimable_bytes;
+ } else {
+ assert(reclaimable_bytes == 0, "invariant");
}
- _markedRegions.clear();
- _curMarkedIndex = 0;
- _numMarkedRegions = 0;
- _cache.clear();
-};
-
-void
-CollectionSetChooser::updateAfterFullCollection() {
- clearMarkedHeapRegions();
}
-// if time_remaining < 0.0, then this method should try to return
-// a region, whether it fits within the remaining time or not
-HeapRegion*
-CollectionSetChooser::getNextMarkedRegion(double time_remaining,
- double avg_prediction) {
- G1CollectedHeap* g1h = G1CollectedHeap::heap();
- G1CollectorPolicy* g1p = g1h->g1_policy();
- fillCache();
- if (_cache.is_empty()) {
- assert(_curMarkedIndex == _numMarkedRegions,
- "if cache is empty, list should also be empty");
- ergo_verbose0(ErgoCSetConstruction,
- "stop adding old regions to CSet",
- ergo_format_reason("cache is empty"));
- return NULL;
- }
-
- HeapRegion *hr = _cache.get_first();
- assert(hr != NULL, "if cache not empty, first entry should be non-null");
- double predicted_time = g1h->predict_region_elapsed_time_ms(hr, false);
-
- if (g1p->adaptive_young_list_length()) {
- if (time_remaining - predicted_time < 0.0) {
- g1h->check_if_region_is_too_expensive(predicted_time);
- ergo_verbose2(ErgoCSetConstruction,
- "stop adding old regions to CSet",
- ergo_format_reason("predicted old region time higher than remaining time")
- ergo_format_ms("predicted old region time")
- ergo_format_ms("remaining time"),
- predicted_time, time_remaining);
- return NULL;
- }
- } else {
- double threshold = 2.0 * avg_prediction;
- if (predicted_time > threshold) {
- ergo_verbose2(ErgoCSetConstruction,
- "stop adding old regions to CSet",
- ergo_format_reason("predicted old region time higher than threshold")
- ergo_format_ms("predicted old region time")
- ergo_format_ms("threshold"),
- predicted_time, threshold);
- return NULL;
+void CollectionSetChooser::clearMarkedHeapRegions() {
+ for (int i = 0; i < _markedRegions.length(); i++) {
+ HeapRegion* r = _markedRegions.at(i);
+ if (r != NULL) {
+ r->set_sort_index(-1);
}
}
-
- HeapRegion *hr2 = _cache.remove_first();
- assert(hr == hr2, "cache contents should not have changed");
-
- return hr;
-}
+ _markedRegions.clear();
+ _curr_index = 0;
+ _length = 0;
+ _remainingReclaimableBytes = 0;
+};