# HG changeset patch # User ysr # Date 1233002841 28800 # Node ID 5cfd8d19e54697f32355997a06c6abb59a08e1d8 # Parent 2b1de1db9a9d5147c93302f6262da6a238942a7e 6786503: Overflow list performance can be improved Summary: Avoid overflow list walk in CMS & ParNew when it is unnecessary. Fix a couple of correctness issues, including a C-heap leak, in ParNew at the intersection of promotion failure, work queue overflow and object array chunking. Add stress testing option and related assertion checking. Reviewed-by: jmasa diff -r 2b1de1db9a9d -r 5cfd8d19e546 src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp --- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp Wed Jan 21 13:40:10 2009 -0800 +++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp Mon Jan 26 12:47:21 2009 -0800 @@ -8508,7 +8508,7 @@ size_t i = num; oop cur = _overflow_list; const markOop proto = markOopDesc::prototype(); - NOT_PRODUCT(size_t n = 0;) + NOT_PRODUCT(ssize_t n = 0;) for (oop next; i > 0 && cur != NULL; cur = next, i--) { next = oop(cur->mark()); cur->set_mark(proto); // until proven otherwise @@ -8525,45 +8525,131 @@ return !stack->isEmpty(); } -// Multi-threaded; use CAS to break off a prefix +#define BUSY (oop(0x1aff1aff)) +// (MT-safe) Get a prefix of at most "num" from the list. +// The overflow list is chained through the mark word of +// each object in the list. We fetch the entire list, +// break off a prefix of the right size and return the +// remainder. If other threads try to take objects from +// the overflow list at that time, they will wait for +// some time to see if data becomes available. If (and +// only if) another thread places one or more object(s) +// on the global list before we have returned the suffix +// to the global list, we will walk down our local list +// to find its end and append the global list to +// our suffix before returning it. This suffix walk can +// prove to be expensive (quadratic in the amount of traffic) +// when there are many objects in the overflow list and +// there is much producer-consumer contention on the list. +// *NOTE*: The overflow list manipulation code here and +// in ParNewGeneration:: are very similar in shape, +// except that in the ParNew case we use the old (from/eden) +// copy of the object to thread the list via its klass word. +// Because of the common code, if you make any changes in +// the code below, please check the ParNew version to see if +// similar changes might be needed. +// CR 6797058 has been filed to consolidate the common code. bool CMSCollector::par_take_from_overflow_list(size_t num, OopTaskQueue* work_q) { - assert(work_q->size() == 0, "That's the current policy"); + assert(work_q->size() == 0, "First empty local work queue"); assert(num < work_q->max_elems(), "Can't bite more than we can chew"); if (_overflow_list == NULL) { return false; } // Grab the entire list; we'll put back a suffix - oop prefix = (oop)Atomic::xchg_ptr(NULL, &_overflow_list); - if (prefix == NULL) { // someone grabbed it before we did ... - // ... we could spin for a short while, but for now we don't - return false; - } + oop prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); + Thread* tid = Thread::current(); + size_t CMSOverflowSpinCount = (size_t)ParallelGCThreads; + size_t sleep_time_millis = MAX2((size_t)1, num/100); + // If the list is busy, we spin for a short while, + // sleeping between attempts to get the list. + for (size_t spin = 0; prefix == BUSY && spin < CMSOverflowSpinCount; spin++) { + os::sleep(tid, sleep_time_millis, false); + if (_overflow_list == NULL) { + // Nothing left to take + return false; + } else if (_overflow_list != BUSY) { + // Try and grab the prefix + prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); + } + } + // If the list was found to be empty, or we spun long + // enough, we give up and return empty-handed. If we leave + // the list in the BUSY state below, it must be the case that + // some other thread holds the overflow list and will set it + // to a non-BUSY state in the future. + if (prefix == NULL || prefix == BUSY) { + // Nothing to take or waited long enough + if (prefix == NULL) { + // Write back the NULL in case we overwrote it with BUSY above + // and it is still the same value. + (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); + } + return false; + } + assert(prefix != NULL && prefix != BUSY, "Error"); size_t i = num; oop cur = prefix; + // Walk down the first "num" objects, unless we reach the end. for (; i > 1 && cur->mark() != NULL; cur = oop(cur->mark()), i--); - if (cur->mark() != NULL) { + if (cur->mark() == NULL) { + // We have "num" or fewer elements in the list, so there + // is nothing to return to the global list. + // Write back the NULL in lieu of the BUSY we wrote + // above, if it is still the same value. + if (_overflow_list == BUSY) { + (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); + } + } else { + // Chop off the suffix and rerturn it to the global list. + assert(cur->mark() != BUSY, "Error"); oop suffix_head = cur->mark(); // suffix will be put back on global list cur->set_mark(NULL); // break off suffix - // Find tail of suffix so we can prepend suffix to global list - for (cur = suffix_head; cur->mark() != NULL; cur = (oop)(cur->mark())); - oop suffix_tail = cur; - assert(suffix_tail != NULL && suffix_tail->mark() == NULL, - "Tautology"); + // It's possible that the list is still in the empty(busy) state + // we left it in a short while ago; in that case we may be + // able to place back the suffix without incurring the cost + // of a walk down the list. oop observed_overflow_list = _overflow_list; - do { - cur = observed_overflow_list; - suffix_tail->set_mark(markOop(cur)); + oop cur_overflow_list = observed_overflow_list; + bool attached = false; + while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { observed_overflow_list = - (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur); - } while (cur != observed_overflow_list); + (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); + if (cur_overflow_list == observed_overflow_list) { + attached = true; + break; + } else cur_overflow_list = observed_overflow_list; + } + if (!attached) { + // Too bad, someone else sneaked in (at least) an element; we'll need + // to do a splice. Find tail of suffix so we can prepend suffix to global + // list. + for (cur = suffix_head; cur->mark() != NULL; cur = (oop)(cur->mark())); + oop suffix_tail = cur; + assert(suffix_tail != NULL && suffix_tail->mark() == NULL, + "Tautology"); + observed_overflow_list = _overflow_list; + do { + cur_overflow_list = observed_overflow_list; + if (cur_overflow_list != BUSY) { + // Do the splice ... + suffix_tail->set_mark(markOop(cur_overflow_list)); + } else { // cur_overflow_list == BUSY + suffix_tail->set_mark(NULL); + } + // ... and try to place spliced list back on overflow_list ... + observed_overflow_list = + (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); + } while (cur_overflow_list != observed_overflow_list); + // ... until we have succeeded in doing so. + } } // Push the prefix elements on work_q assert(prefix != NULL, "control point invariant"); const markOop proto = markOopDesc::prototype(); oop next; - NOT_PRODUCT(size_t n = 0;) + NOT_PRODUCT(ssize_t n = 0;) for (cur = prefix; cur != NULL; cur = next) { next = oop(cur->mark()); cur->set_mark(proto); // until proven otherwise @@ -8597,11 +8683,16 @@ oop cur_overflow_list; do { cur_overflow_list = observed_overflow_list; - p->set_mark(markOop(cur_overflow_list)); + if (cur_overflow_list != BUSY) { + p->set_mark(markOop(cur_overflow_list)); + } else { + p->set_mark(NULL); + } observed_overflow_list = (oop) Atomic::cmpxchg_ptr(p, &_overflow_list, cur_overflow_list); } while (cur_overflow_list != observed_overflow_list); } +#undef BUSY // Single threaded // General Note on GrowableArray: pushes may silently fail @@ -8610,7 +8701,7 @@ // a lot of code in the JVM. The prudent thing for GrowableArray // to do (for now) is to exit with an error. However, that may // be too draconian in some cases because the caller may be -// able to recover without much harm. For suych cases, we +// able to recover without much harm. For such cases, we // should probably introduce a "soft_push" method which returns // an indication of success or failure with the assumption that // the caller may be able to recover from a failure; code in @@ -8618,8 +8709,6 @@ // failures where possible, thus, incrementally hardening the VM // in such low resource situations. void CMSCollector::preserve_mark_work(oop p, markOop m) { - int PreserveMarkStackSize = 128; - if (_preserved_oop_stack == NULL) { assert(_preserved_mark_stack == NULL, "bijection with preserved_oop_stack"); diff -r 2b1de1db9a9d -r 5cfd8d19e546 src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp --- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp Wed Jan 21 13:40:10 2009 -0800 +++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp Mon Jan 26 12:47:21 2009 -0800 @@ -595,7 +595,7 @@ size_t _ser_kac_preclean_ovflw; size_t _ser_kac_ovflw; size_t _par_kac_ovflw; - NOT_PRODUCT(size_t _num_par_pushes;) + NOT_PRODUCT(ssize_t _num_par_pushes;) // ("Weak") Reference processing support ReferenceProcessor* _ref_processor; diff -r 2b1de1db9a9d -r 5cfd8d19e546 src/share/vm/gc_implementation/includeDB_gc_parNew --- a/src/share/vm/gc_implementation/includeDB_gc_parNew Wed Jan 21 13:40:10 2009 -0800 +++ b/src/share/vm/gc_implementation/includeDB_gc_parNew Mon Jan 26 12:47:21 2009 -0800 @@ -77,6 +77,7 @@ parNewGeneration.cpp sharedHeap.hpp parNewGeneration.cpp space.hpp parNewGeneration.cpp spaceDecorator.hpp +parNewGeneration.cpp thread.hpp parNewGeneration.cpp workgroup.hpp parNewGeneration.hpp defNewGeneration.hpp diff -r 2b1de1db9a9d -r 5cfd8d19e546 src/share/vm/gc_implementation/parNew/parNewGeneration.cpp --- a/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp Wed Jan 21 13:40:10 2009 -0800 +++ b/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp Mon Jan 26 12:47:21 2009 -0800 @@ -404,6 +404,8 @@ if (terminator()->offer_termination()) break; par_scan_state()->end_term_time(); } + assert(par_gen()->_overflow_list == NULL && par_gen()->_num_par_pushes == 0, + "Broken overflow list?"); // Finish the last termination pause. par_scan_state()->end_term_time(); } @@ -456,6 +458,8 @@ _is_alive_closure(this), _plab_stats(YoungPLABSize, PLABWeight) { + NOT_PRODUCT(_overflow_counter = ParGCWorkQueueOverflowInterval;) + NOT_PRODUCT(_num_par_pushes = 0;) _task_queues = new ObjToScanQueueSet(ParallelGCThreads); guarantee(_task_queues != NULL, "task_queues allocation failure."); @@ -993,12 +997,19 @@ "push forwarded object"); } // Push it on one of the queues of to-be-scanned objects. - if (!par_scan_state->work_queue()->push(obj_to_push)) { + bool simulate_overflow = false; + NOT_PRODUCT( + if (ParGCWorkQueueOverflowALot && should_simulate_overflow()) { + // simulate a stack overflow + simulate_overflow = true; + } + ) + if (simulate_overflow || !par_scan_state->work_queue()->push(obj_to_push)) { // Add stats for overflow pushes. if (Verbose && PrintGCDetails) { gclog_or_tty->print("queue overflow!\n"); } - push_on_overflow_list(old); + push_on_overflow_list(old, par_scan_state); par_scan_state->note_overflow_push(); } par_scan_state->note_push(); @@ -1110,9 +1121,16 @@ "push forwarded object"); } // Push it on one of the queues of to-be-scanned objects. - if (!par_scan_state->work_queue()->push(obj_to_push)) { + bool simulate_overflow = false; + NOT_PRODUCT( + if (ParGCWorkQueueOverflowALot && should_simulate_overflow()) { + // simulate a stack overflow + simulate_overflow = true; + } + ) + if (simulate_overflow || !par_scan_state->work_queue()->push(obj_to_push)) { // Add stats for overflow pushes. - push_on_overflow_list(old); + push_on_overflow_list(old, par_scan_state); par_scan_state->note_overflow_push(); } par_scan_state->note_push(); @@ -1135,89 +1153,190 @@ return forward_ptr; } -void ParNewGeneration::push_on_overflow_list(oop from_space_obj) { - oop cur_overflow_list = _overflow_list; +#ifndef PRODUCT +// It's OK to call this multi-threaded; the worst thing +// that can happen is that we'll get a bunch of closely +// spaced simulated oveflows, but that's OK, in fact +// probably good as it would exercise the overflow code +// under contention. +bool ParNewGeneration::should_simulate_overflow() { + if (_overflow_counter-- <= 0) { // just being defensive + _overflow_counter = ParGCWorkQueueOverflowInterval; + return true; + } else { + return false; + } +} +#endif + +#define BUSY (oop(0x1aff1aff)) +void ParNewGeneration::push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state) { // if the object has been forwarded to itself, then we cannot // use the klass pointer for the linked list. Instead we have // to allocate an oopDesc in the C-Heap and use that for the linked list. + // XXX This is horribly inefficient when a promotion failure occurs + // and should be fixed. XXX FIX ME !!! +#ifndef PRODUCT + Atomic::inc_ptr(&_num_par_pushes); + assert(_num_par_pushes > 0, "Tautology"); +#endif if (from_space_obj->forwardee() == from_space_obj) { oopDesc* listhead = NEW_C_HEAP_ARRAY(oopDesc, 1); listhead->forward_to(from_space_obj); from_space_obj = listhead; } - while (true) { - from_space_obj->set_klass_to_list_ptr(cur_overflow_list); - oop observed_overflow_list = + oop observed_overflow_list = _overflow_list; + oop cur_overflow_list; + do { + cur_overflow_list = observed_overflow_list; + if (cur_overflow_list != BUSY) { + from_space_obj->set_klass_to_list_ptr(cur_overflow_list); + } else { + from_space_obj->set_klass_to_list_ptr(NULL); + } + observed_overflow_list = (oop)Atomic::cmpxchg_ptr(from_space_obj, &_overflow_list, cur_overflow_list); - if (observed_overflow_list == cur_overflow_list) break; - // Otherwise... - cur_overflow_list = observed_overflow_list; - } + } while (cur_overflow_list != observed_overflow_list); } +// *NOTE*: The overflow list manipulation code here and +// in CMSCollector:: are very similar in shape, +// except that in the CMS case we thread the objects +// directly into the list via their mark word, and do +// not need to deal with special cases below related +// to chunking of object arrays and promotion failure +// handling. +// CR 6797058 has been filed to attempt consolidation of +// the common code. +// Because of the common code, if you make any changes in +// the code below, please check the CMS version to see if +// similar changes might be needed. +// See CMSCollector::par_take_from_overflow_list() for +// more extensive documentation comments. bool ParNewGeneration::take_from_overflow_list(ParScanThreadState* par_scan_state) { ObjToScanQueue* work_q = par_scan_state->work_queue(); + assert(work_q->size() == 0, "Should first empty local work queue"); // How many to take? - int objsFromOverflow = MIN2(work_q->max_elems()/4, - (juint)ParGCDesiredObjsFromOverflowList); + size_t objsFromOverflow = MIN2((size_t)work_q->max_elems()/4, + (size_t)ParGCDesiredObjsFromOverflowList); if (_overflow_list == NULL) return false; // Otherwise, there was something there; try claiming the list. - oop prefix = (oop)Atomic::xchg_ptr(NULL, &_overflow_list); - - if (prefix == NULL) { - return false; + oop prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); + // Trim off a prefix of at most objsFromOverflow items + Thread* tid = Thread::current(); + size_t spin_count = (size_t)ParallelGCThreads; + size_t sleep_time_millis = MAX2((size_t)1, objsFromOverflow/100); + for (size_t spin = 0; prefix == BUSY && spin < spin_count; spin++) { + // someone grabbed it before we did ... + // ... we spin for a short while... + os::sleep(tid, sleep_time_millis, false); + if (_overflow_list == NULL) { + // nothing left to take + return false; + } else if (_overflow_list != BUSY) { + // try and grab the prefix + prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); + } } - // Trim off a prefix of at most objsFromOverflow items - int i = 1; + if (prefix == NULL || prefix == BUSY) { + // Nothing to take or waited long enough + if (prefix == NULL) { + // Write back the NULL in case we overwrote it with BUSY above + // and it is still the same value. + (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); + } + return false; + } + assert(prefix != NULL && prefix != BUSY, "Error"); + size_t i = 1; oop cur = prefix; while (i < objsFromOverflow && cur->klass_or_null() != NULL) { i++; cur = oop(cur->klass()); } // Reattach remaining (suffix) to overflow list - if (cur->klass_or_null() != NULL) { - oop suffix = oop(cur->klass()); - cur->set_klass_to_list_ptr(NULL); - - // Find last item of suffix list - oop last = suffix; - while (last->klass_or_null() != NULL) { - last = oop(last->klass()); + if (cur->klass_or_null() == NULL) { + // Write back the NULL in lieu of the BUSY we wrote + // above and it is still the same value. + if (_overflow_list == BUSY) { + (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); } - // Atomically prepend suffix to current overflow list - oop cur_overflow_list = _overflow_list; - while (true) { - last->set_klass_to_list_ptr(cur_overflow_list); - oop observed_overflow_list = - (oop)Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); - if (observed_overflow_list == cur_overflow_list) break; - // Otherwise... - cur_overflow_list = observed_overflow_list; + } else { + assert(cur->klass_or_null() != BUSY, "Error"); + oop suffix = oop(cur->klass()); // suffix will be put back on global list + cur->set_klass_to_list_ptr(NULL); // break off suffix + // It's possible that the list is still in the empty(busy) state + // we left it in a short while ago; in that case we may be + // able to place back the suffix. + oop observed_overflow_list = _overflow_list; + oop cur_overflow_list = observed_overflow_list; + bool attached = false; + while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { + observed_overflow_list = + (oop) Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); + if (cur_overflow_list == observed_overflow_list) { + attached = true; + break; + } else cur_overflow_list = observed_overflow_list; + } + if (!attached) { + // Too bad, someone else got in in between; we'll need to do a splice. + // Find the last item of suffix list + oop last = suffix; + while (last->klass_or_null() != NULL) { + last = oop(last->klass()); + } + // Atomically prepend suffix to current overflow list + observed_overflow_list = _overflow_list; + do { + cur_overflow_list = observed_overflow_list; + if (cur_overflow_list != BUSY) { + // Do the splice ... + last->set_klass_to_list_ptr(cur_overflow_list); + } else { // cur_overflow_list == BUSY + last->set_klass_to_list_ptr(NULL); + } + observed_overflow_list = + (oop)Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); + } while (cur_overflow_list != observed_overflow_list); } } // Push objects on prefix list onto this thread's work queue - assert(cur != NULL, "program logic"); + assert(prefix != NULL && prefix != BUSY, "program logic"); cur = prefix; - int n = 0; + ssize_t n = 0; while (cur != NULL) { oop obj_to_push = cur->forwardee(); oop next = oop(cur->klass_or_null()); cur->set_klass(obj_to_push->klass()); - if (par_scan_state->should_be_partially_scanned(obj_to_push, cur)) { - obj_to_push = cur; + // This may be an array object that is self-forwarded. In that case, the list pointer + // space, cur, is not in the Java heap, but rather in the C-heap and should be freed. + if (!is_in_reserved(cur)) { + // This can become a scaling bottleneck when there is work queue overflow coincident + // with promotion failure. + oopDesc* f = cur; + FREE_C_HEAP_ARRAY(oopDesc, f); + } else if (par_scan_state->should_be_partially_scanned(obj_to_push, cur)) { assert(arrayOop(cur)->length() == 0, "entire array remaining to be scanned"); + obj_to_push = cur; } - work_q->push(obj_to_push); + bool ok = work_q->push(obj_to_push); + assert(ok, "Should have succeeded"); cur = next; n++; } par_scan_state->note_overflow_refill(n); +#ifndef PRODUCT + assert(_num_par_pushes >= n, "Too many pops?"); + Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); +#endif return true; } +#undef BUSY void ParNewGeneration::ref_processor_init() { diff -r 2b1de1db9a9d -r 5cfd8d19e546 src/share/vm/gc_implementation/parNew/parNewGeneration.hpp --- a/src/share/vm/gc_implementation/parNew/parNewGeneration.hpp Wed Jan 21 13:40:10 2009 -0800 +++ b/src/share/vm/gc_implementation/parNew/parNewGeneration.hpp Mon Jan 26 12:47:21 2009 -0800 @@ -278,6 +278,7 @@ friend class ParNewRefProcTask; friend class ParNewRefProcTaskExecutor; friend class ParScanThreadStateSet; + friend class ParEvacuateFollowersClosure; private: // XXX use a global constant instead of 64! @@ -296,6 +297,7 @@ // klass-pointers (klass information already copied to the forwarded // image.) Manipulated with CAS. oop _overflow_list; + NOT_PRODUCT(ssize_t _num_par_pushes;) // If true, older generation does not support promotion undo, so avoid. static bool _avoid_promotion_undo; @@ -372,8 +374,12 @@ oop copy_to_survivor_space_with_undo(ParScanThreadState* par_scan_state, oop obj, size_t obj_sz, markOop m); + // in support of testing overflow code + NOT_PRODUCT(int _overflow_counter;) + NOT_PRODUCT(bool should_simulate_overflow();) + // Push the given (from-space) object on the global overflow list. - void push_on_overflow_list(oop from_space_obj); + void push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state); // If the global overflow list is non-empty, move some tasks from it // onto "work_q" (which must be empty). No more than 1/4 of the diff -r 2b1de1db9a9d -r 5cfd8d19e546 src/share/vm/memory/referenceProcessor.cpp --- a/src/share/vm/memory/referenceProcessor.cpp Wed Jan 21 13:40:10 2009 -0800 +++ b/src/share/vm/memory/referenceProcessor.cpp Mon Jan 26 12:47:21 2009 -0800 @@ -721,12 +721,6 @@ iter.obj(), iter.obj()->blueprint()->internal_name()); } assert(iter.obj()->is_oop(UseConcMarkSweepGC), "Adding a bad reference"); - // If discovery is concurrent, we may have objects with null referents, - // being those that were concurrently cleared after they were discovered - // (and not subsequently precleaned). - assert( (discovery_is_atomic() && iter.referent()->is_oop()) - || (!discovery_is_atomic() && iter.referent()->is_oop_or_null(UseConcMarkSweepGC)), - "Adding a bad referent"); iter.next(); } // Remember to keep sentinel pointer around diff -r 2b1de1db9a9d -r 5cfd8d19e546 src/share/vm/runtime/globals.hpp --- a/src/share/vm/runtime/globals.hpp Wed Jan 21 13:40:10 2009 -0800 +++ b/src/share/vm/runtime/globals.hpp Mon Jan 26 12:47:21 2009 -0800 @@ -1307,7 +1307,14 @@ product(intx, ParGCArrayScanChunk, 50, \ "Scan a subset and push remainder, if array is bigger than this") \ \ - product(intx, ParGCDesiredObjsFromOverflowList, 20, \ + notproduct(bool, ParGCWorkQueueOverflowALot, false, \ + "Whether we should simulate work queue overflow in ParNew") \ + \ + notproduct(uintx, ParGCWorkQueueOverflowInterval, 1000, \ + "An `interval' counter that determines how frequently" \ + " we simulate overflow; a smaller number increases frequency") \ + \ + product(uintx, ParGCDesiredObjsFromOverflowList, 20, \ "The desired number of objects to claim from the overflow list") \ \ product(uintx, CMSParPromoteBlocksToClaim, 50, \ @@ -1429,8 +1436,8 @@ "Whether we should simulate frequent marking stack / work queue" \ " overflow") \ \ - notproduct(intx, CMSMarkStackOverflowInterval, 1000, \ - "A per-thread `interval' counter that determines how frequently" \ + notproduct(uintx, CMSMarkStackOverflowInterval, 1000, \ + "An `interval' counter that determines how frequently" \ " we simulate overflow; a smaller number increases frequency") \ \ product(uintx, CMSMaxAbortablePrecleanLoops, 0, \ @@ -1648,7 +1655,7 @@ develop(uintx, WorkStealingYieldsBeforeSleep, 1000, \ "Number of yields before a sleep is done during workstealing") \ \ - product(uintx, PreserveMarkStackSize, 40, \ + product(uintx, PreserveMarkStackSize, 1024, \ "Size for stack used in promotion failure handling") \ \ product_pd(bool, UseTLAB, "Use thread-local object allocation") \