changeset 2153:a7214d79fcf1

6896603: CMS/GCH: collection_attempt_is_safe() ergo should use more recent data Summary: Deprecated HandlePromotionFailure, removing the ability to turn off that feature, did away with one epoch look-ahead when deciding if a scavenge is likely to fail, relying on current data. Reviewed-by: jmasa, johnc, poonam
author ysr
date Sat, 23 Oct 2010 23:03:49 -0700
parents cd3ef3fd20dd
children c766bae6c14d
files src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp src/share/vm/gc_implementation/parNew/parNewGeneration.cpp src/share/vm/memory/collectorPolicy.cpp src/share/vm/memory/defNewGeneration.cpp src/share/vm/memory/defNewGeneration.hpp src/share/vm/memory/genCollectedHeap.cpp src/share/vm/memory/genCollectedHeap.hpp src/share/vm/memory/generation.cpp src/share/vm/memory/generation.hpp src/share/vm/memory/tenuredGeneration.cpp src/share/vm/memory/tenuredGeneration.hpp src/share/vm/runtime/arguments.cpp src/share/vm/runtime/globals.hpp
diffstat 14 files changed, 103 insertions(+), 224 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Sat Oct 23 23:03:49 2010 -0700
@@ -354,12 +354,8 @@
 double CMSStats::time_until_cms_gen_full() const {
   size_t cms_free = _cms_gen->cmsSpace()->free();
   GenCollectedHeap* gch = GenCollectedHeap::heap();
-  size_t expected_promotion = gch->get_gen(0)->capacity();
-  if (HandlePromotionFailure) {
-    expected_promotion = MIN2(
-        (size_t) _cms_gen->gc_stats()->avg_promoted()->padded_average(),
-        expected_promotion);
-  }
+  size_t expected_promotion = MIN2(gch->get_gen(0)->capacity(),
+                                   (size_t) _cms_gen->gc_stats()->avg_promoted()->padded_average());
   if (cms_free > expected_promotion) {
     // Start a cms collection if there isn't enough space to promote
     // for the next minor collection.  Use the padded average as
@@ -865,57 +861,18 @@
   return free() + _virtual_space.uncommitted_size();
 }
 
-bool ConcurrentMarkSweepGeneration::promotion_attempt_is_safe(
-    size_t max_promotion_in_bytes,
-    bool younger_handles_promotion_failure) const {
-
-  // This is the most conservative test.  Full promotion is
-  // guaranteed if this is used. The multiplicative factor is to
-  // account for the worst case "dilatation".
-  double adjusted_max_promo_bytes = _dilatation_factor * max_promotion_in_bytes;
-  if (adjusted_max_promo_bytes > (double)max_uintx) { // larger than size_t
-    adjusted_max_promo_bytes = (double)max_uintx;
-  }
-  bool result = (max_contiguous_available() >= (size_t)adjusted_max_promo_bytes);
-
-  if (younger_handles_promotion_failure && !result) {
-    // Full promotion is not guaranteed because fragmentation
-    // of the cms generation can prevent the full promotion.
-    result = (max_available() >= (size_t)adjusted_max_promo_bytes);
-
-    if (!result) {
-      // With promotion failure handling the test for the ability
-      // to support the promotion does not have to be guaranteed.
-      // Use an average of the amount promoted.
-      result = max_available() >= (size_t)
-        gc_stats()->avg_promoted()->padded_average();
-      if (PrintGC && Verbose && result) {
-        gclog_or_tty->print_cr(
-          "\nConcurrentMarkSweepGeneration::promotion_attempt_is_safe"
-          " max_available: " SIZE_FORMAT
-          " avg_promoted: " SIZE_FORMAT,
-          max_available(), (size_t)
-          gc_stats()->avg_promoted()->padded_average());
-      }
-    } else {
-      if (PrintGC && Verbose) {
-        gclog_or_tty->print_cr(
-          "\nConcurrentMarkSweepGeneration::promotion_attempt_is_safe"
-          " max_available: " SIZE_FORMAT
-          " adj_max_promo_bytes: " SIZE_FORMAT,
-          max_available(), (size_t)adjusted_max_promo_bytes);
-      }
-    }
-  } else {
-    if (PrintGC && Verbose) {
-      gclog_or_tty->print_cr(
-        "\nConcurrentMarkSweepGeneration::promotion_attempt_is_safe"
-        " contiguous_available: " SIZE_FORMAT
-        " adj_max_promo_bytes: " SIZE_FORMAT,
-        max_contiguous_available(), (size_t)adjusted_max_promo_bytes);
-    }
-  }
-  return result;
+bool ConcurrentMarkSweepGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
+  size_t available = max_available();
+  size_t av_promo  = (size_t)gc_stats()->avg_promoted()->padded_average();
+  bool   res = (available >= av_promo) || (available >= max_promotion_in_bytes);
+  if (PrintGC && Verbose) {
+    gclog_or_tty->print_cr(
+      "CMS: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT"),"
+      "max_promo("SIZE_FORMAT")",
+      res? "":" not", available, res? ">=":"<",
+      av_promo, max_promotion_in_bytes);
+  }
+  return res;
 }
 
 // At a promotion failure dump information on block layout in heap
@@ -6091,23 +6048,14 @@
   assert(_collectorState == Resizing, "Change of collector state to"
     " Resizing must be done under the freelistLocks (plural)");
 
-  // Now that sweeping has been completed, if the GCH's
-  // incremental_collection_will_fail flag is set, clear it,
+  // Now that sweeping has been completed, we clear
+  // the incremental_collection_failed flag,
   // thus inviting a younger gen collection to promote into
   // this generation. If such a promotion may still fail,
   // the flag will be set again when a young collection is
   // attempted.
-  // I think the incremental_collection_will_fail flag's use
-  // is specific to a 2 generation collection policy, so i'll
-  // assert that that's the configuration we are operating within.
-  // The use of the flag can and should be generalized appropriately
-  // in the future to deal with a general n-generation system.
-
   GenCollectedHeap* gch = GenCollectedHeap::heap();
-  assert(gch->collector_policy()->is_two_generation_policy(),
-         "Resetting of incremental_collection_will_fail flag"
-         " may be incorrect otherwise");
-  gch->clear_incremental_collection_will_fail();
+  gch->clear_incremental_collection_failed();  // Worth retrying as fresh space may have been freed up
   gch->update_full_collections_completed(_collection_count_start);
 }
 
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp	Sat Oct 23 23:03:49 2010 -0700
@@ -1185,8 +1185,7 @@
   virtual void par_promote_alloc_done(int thread_num);
   virtual void par_oop_since_save_marks_iterate_done(int thread_num);
 
-  virtual bool promotion_attempt_is_safe(size_t promotion_in_bytes,
-    bool younger_handles_promotion_failure) const;
+  virtual bool promotion_attempt_is_safe(size_t promotion_in_bytes) const;
 
   // Inform this (non-young) generation that a promotion failure was
   // encountered during a collection of a younger generation that
--- a/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp	Sat Oct 23 23:03:49 2010 -0700
@@ -846,7 +846,7 @@
   // from this generation, pass on collection; let the next generation
   // do it.
   if (!collection_attempt_is_safe()) {
-    gch->set_incremental_collection_will_fail();
+    gch->set_incremental_collection_failed();  // slight lie, in that we did not even attempt one
     return;
   }
   assert(to()->is_empty(), "Else not collection_attempt_is_safe");
@@ -935,8 +935,6 @@
 
     assert(to()->is_empty(), "to space should be empty now");
   } else {
-    assert(HandlePromotionFailure,
-      "Should only be here if promotion failure handling is on");
     assert(_promo_failure_scan_stack.is_empty(), "post condition");
     _promo_failure_scan_stack.clear(true); // Clear cached segments.
 
@@ -947,7 +945,7 @@
     // All the spaces are in play for mark-sweep.
     swap_spaces();  // Make life simpler for CMS || rescan; see 6483690.
     from()->set_next_compaction_space(to());
-    gch->set_incremental_collection_will_fail();
+    gch->set_incremental_collection_failed();
     // Inform the next generation that a promotion failure occurred.
     _next_gen->promotion_failure_occurred();
 
@@ -1092,11 +1090,6 @@
                                        old, m, sz);
 
     if (new_obj == NULL) {
-      if (!HandlePromotionFailure) {
-        // A failed promotion likely means the MaxLiveObjectEvacuationRatio flag
-        // is incorrectly set. In any case, its seriously wrong to be here!
-        vm_exit_out_of_memory(sz*wordSize, "promotion");
-      }
       // promotion failed, forward to self
       _promotion_failed = true;
       new_obj = old;
@@ -1206,12 +1199,6 @@
                                        old, m, sz);
 
     if (new_obj == NULL) {
-      if (!HandlePromotionFailure) {
-        // A failed promotion likely means the MaxLiveObjectEvacuationRatio
-        // flag is incorrectly set. In any case, its seriously wrong to be
-        // here!
-        vm_exit_out_of_memory(sz*wordSize, "promotion");
-      }
       // promotion failed, forward to self
       forward_ptr = old->forward_to_atomic(old);
       new_obj = old;
--- a/src/share/vm/memory/collectorPolicy.cpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/memory/collectorPolicy.cpp	Sat Oct 23 23:03:49 2010 -0700
@@ -659,9 +659,6 @@
     }
     return result;   // could be null if we are out of space
   } else if (!gch->incremental_collection_will_fail()) {
-    // The gc_prologues have not executed yet.  The value
-    // for incremental_collection_will_fail() is the remanent
-    // of the last collection.
     // Do an incremental collection.
     gch->do_collection(false            /* full */,
                        false            /* clear_all_soft_refs */,
@@ -739,9 +736,8 @@
   GenCollectedHeap* gch = GenCollectedHeap::heap();
   size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc();
   return    (word_size > heap_word_size(gen0_capacity))
-         || (GC_locker::is_active_and_needs_gc())
-         || (   gch->last_incremental_collection_failed()
-             && gch->incremental_collection_will_fail());
+         || GC_locker::is_active_and_needs_gc()
+         || gch->incremental_collection_failed();
 }
 
 
--- a/src/share/vm/memory/defNewGeneration.cpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/memory/defNewGeneration.cpp	Sat Oct 23 23:03:49 2010 -0700
@@ -510,7 +510,7 @@
   // from this generation, pass on collection; let the next generation
   // do it.
   if (!collection_attempt_is_safe()) {
-    gch->set_incremental_collection_will_fail();
+    gch->set_incremental_collection_failed(); // Slight lie: we did not even attempt one
     return;
   }
   assert(to()->is_empty(), "Else not collection_attempt_is_safe");
@@ -596,9 +596,8 @@
     if (PrintGC && !PrintGCDetails) {
       gch->print_heap_change(gch_prev_used);
     }
+    assert(!gch->incremental_collection_failed(), "Should be clear");
   } else {
-    assert(HandlePromotionFailure,
-      "Should not be here unless promotion failure handling is on");
     assert(_promo_failure_scan_stack.is_empty(), "post condition");
     _promo_failure_scan_stack.clear(true); // Clear cached segments.
 
@@ -613,7 +612,7 @@
     // and from-space.
     swap_spaces();   // For uniformity wrt ParNewGeneration.
     from()->set_next_compaction_space(to());
-    gch->set_incremental_collection_will_fail();
+    gch->set_incremental_collection_failed();
 
     // Inform the next generation that a promotion failure occurred.
     _next_gen->promotion_failure_occurred();
@@ -700,12 +699,6 @@
   if (obj == NULL) {
     obj = _next_gen->promote(old, s);
     if (obj == NULL) {
-      if (!HandlePromotionFailure) {
-        // A failed promotion likely means the MaxLiveObjectEvacuationRatio flag
-        // is incorrectly set. In any case, its seriously wrong to be here!
-        vm_exit_out_of_memory(s*wordSize, "promotion");
-      }
-
       handle_promotion_failure(old);
       return old;
     }
@@ -812,31 +805,7 @@
     assert(_next_gen != NULL,
            "This must be the youngest gen, and not the only gen");
   }
-
-  // Decide if there's enough room for a full promotion
-  // When using extremely large edens, we effectively lose a
-  // large amount of old space.  Use the "MaxLiveObjectEvacuationRatio"
-  // flag to reduce the minimum evacuation space requirements. If
-  // there is not enough space to evacuate eden during a scavenge,
-  // the VM will immediately exit with an out of memory error.
-  // This flag has not been tested
-  // with collectors other than simple mark & sweep.
-  //
-  // Note that with the addition of promotion failure handling, the
-  // VM will not immediately exit but will undo the young generation
-  // collection.  The parameter is left here for compatibility.
-  const double evacuation_ratio = MaxLiveObjectEvacuationRatio / 100.0;
-
-  // worst_case_evacuation is based on "used()".  For the case where this
-  // method is called after a collection, this is still appropriate because
-  // the case that needs to be detected is one in which a full collection
-  // has been done and has overflowed into the young generation.  In that
-  // case a minor collection will fail (the overflow of the full collection
-  // means there is no space in the old generation for any promotion).
-  size_t worst_case_evacuation = (size_t)(used() * evacuation_ratio);
-
-  return _next_gen->promotion_attempt_is_safe(worst_case_evacuation,
-                                              HandlePromotionFailure);
+  return _next_gen->promotion_attempt_is_safe(used());
 }
 
 void DefNewGeneration::gc_epilogue(bool full) {
@@ -845,14 +814,17 @@
   // a minimum at the end of a collection.  If it is not, then
   // the heap is approaching full.
   GenCollectedHeap* gch = GenCollectedHeap::heap();
-  clear_should_allocate_from_space();
-  if (collection_attempt_is_safe()) {
-    gch->clear_incremental_collection_will_fail();
+  if (full) {
+    assert(!GC_locker::is_active(), "We should not be executing here");
+    if (!collection_attempt_is_safe()) {
+      gch->set_incremental_collection_failed(); // Slight lie: a full gc left us in that state
+      set_should_allocate_from_space(); // we seem to be running out of space
+    } else {
+      gch->clear_incremental_collection_failed(); // We just did a full collection
+      clear_should_allocate_from_space(); // if set
+    }
   } else {
-    gch->set_incremental_collection_will_fail();
-    if (full) { // we seem to be running out of space
-      set_should_allocate_from_space();
-    }
+    assert(!gch->incremental_collection_failed(), "Error");
   }
 
   if (ZapUnusedHeapArea) {
--- a/src/share/vm/memory/defNewGeneration.hpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/memory/defNewGeneration.hpp	Sat Oct 23 23:03:49 2010 -0700
@@ -82,12 +82,6 @@
   Stack<oop>     _objs_with_preserved_marks;
   Stack<markOop> _preserved_marks_of_objs;
 
-  // Returns true if the collection can be safely attempted.
-  // If this method returns false, a collection is not
-  // guaranteed to fail but the system may not be able
-  // to recover from the failure.
-  bool collection_attempt_is_safe();
-
   // Promotion failure handling
   OopClosure *_promo_failure_scan_stack_closure;
   void set_promo_failure_scan_stack_closure(OopClosure *scan_stack_closure) {
@@ -304,6 +298,14 @@
 
   // GC support
   virtual void compute_new_size();
+
+  // Returns true if the collection is likely to be safely
+  // completed. Even if this method returns true, a collection
+  // may not be guaranteed to succeed, and the system should be
+  // able to safely unwind and recover from that failure, albeit
+  // at some additional cost. Override superclass's implementation.
+  virtual bool collection_attempt_is_safe();
+
   virtual void collect(bool   full,
                        bool   clear_all_soft_refs,
                        size_t size,
--- a/src/share/vm/memory/genCollectedHeap.cpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/memory/genCollectedHeap.cpp	Sat Oct 23 23:03:49 2010 -0700
@@ -142,8 +142,7 @@
   }
   _perm_gen = perm_gen_spec->init(heap_rs, PermSize, rem_set());
 
-  clear_incremental_collection_will_fail();
-  clear_last_incremental_collection_failed();
+  clear_incremental_collection_failed();
 
 #ifndef SERIALGC
   // If we are running CMS, create the collector responsible
@@ -1347,17 +1346,6 @@
 };
 
 void GenCollectedHeap::gc_epilogue(bool full) {
-  // Remember if a partial collection of the heap failed, and
-  // we did a complete collection.
-  if (full && incremental_collection_will_fail()) {
-    set_last_incremental_collection_failed();
-  } else {
-    clear_last_incremental_collection_failed();
-  }
-  // Clear the flag, if set; the generation gc_epilogues will set the
-  // flag again if the condition persists despite the collection.
-  clear_incremental_collection_will_fail();
-
 #ifdef COMPILER2
   assert(DerivedPointerTable::is_empty(), "derived pointer present");
   size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
--- a/src/share/vm/memory/genCollectedHeap.hpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/memory/genCollectedHeap.hpp	Sat Oct 23 23:03:49 2010 -0700
@@ -62,11 +62,10 @@
   // The generational collector policy.
   GenCollectorPolicy* _gen_policy;
 
-  // If a generation would bail out of an incremental collection,
-  // it sets this flag.  If the flag is set, satisfy_failed_allocation
-  // will attempt allocating in all generations before doing a full GC.
-  bool _incremental_collection_will_fail;
-  bool _last_incremental_collection_failed;
+  // Indicates that the most recent previous incremental collection failed.
+  // The flag is cleared when an action is taken that might clear the
+  // condition that caused that incremental collection to fail.
+  bool _incremental_collection_failed;
 
   // In support of ExplicitGCInvokesConcurrent functionality
   unsigned int _full_collections_completed;
@@ -469,26 +468,26 @@
   // call to "save_marks".
   bool no_allocs_since_save_marks(int level);
 
+  // Returns true if an incremental collection is likely to fail.
+  bool incremental_collection_will_fail() {
+    // Assumes a 2-generation system; the first disjunct remembers if an
+    // incremental collection failed, even when we thought (second disjunct)
+    // that it would not.
+    assert(heap()->collector_policy()->is_two_generation_policy(),
+           "the following definition may not be suitable for an n(>2)-generation system");
+    return incremental_collection_failed() || !get_gen(0)->collection_attempt_is_safe();
+  }
+
   // If a generation bails out of an incremental collection,
   // it sets this flag.
-  bool incremental_collection_will_fail() {
-    return _incremental_collection_will_fail;
+  bool incremental_collection_failed() const {
+    return _incremental_collection_failed;
   }
-  void set_incremental_collection_will_fail() {
-    _incremental_collection_will_fail = true;
+  void set_incremental_collection_failed() {
+    _incremental_collection_failed = true;
   }
-  void clear_incremental_collection_will_fail() {
-    _incremental_collection_will_fail = false;
-  }
-
-  bool last_incremental_collection_failed() const {
-    return _last_incremental_collection_failed;
-  }
-  void set_last_incremental_collection_failed() {
-    _last_incremental_collection_failed = true;
-  }
-  void clear_last_incremental_collection_failed() {
-    _last_incremental_collection_failed = false;
+  void clear_incremental_collection_failed() {
+    _incremental_collection_failed = false;
   }
 
   // Promotion of obj into gen failed.  Try to promote obj to higher non-perm
--- a/src/share/vm/memory/generation.cpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/memory/generation.cpp	Sat Oct 23 23:03:49 2010 -0700
@@ -165,15 +165,16 @@
   return max;
 }
 
-bool Generation::promotion_attempt_is_safe(size_t promotion_in_bytes,
-                                           bool not_used) const {
+bool Generation::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
+  size_t available = max_contiguous_available();
+  bool   res = (available >= max_promotion_in_bytes);
   if (PrintGC && Verbose) {
-    gclog_or_tty->print_cr("Generation::promotion_attempt_is_safe"
-                " contiguous_available: " SIZE_FORMAT
-                " promotion_in_bytes: " SIZE_FORMAT,
-                max_contiguous_available(), promotion_in_bytes);
+    gclog_or_tty->print_cr(
+      "Generation: promo attempt is%s safe: available("SIZE_FORMAT") %s max_promo("SIZE_FORMAT")",
+      res? "":" not", available, res? ">=":"<",
+      max_promotion_in_bytes);
   }
-  return max_contiguous_available() >= promotion_in_bytes;
+  return res;
 }
 
 // Ignores "ref" and calls allocate().
--- a/src/share/vm/memory/generation.hpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/memory/generation.hpp	Sat Oct 23 23:03:49 2010 -0700
@@ -173,15 +173,11 @@
   // The largest number of contiguous free bytes in this or any higher generation.
   virtual size_t max_contiguous_available() const;
 
-  // Returns true if promotions of the specified amount can
-  // be attempted safely (without a vm failure).
+  // Returns true if promotions of the specified amount are
+  // likely to succeed without a promotion failure.
   // Promotion of the full amount is not guaranteed but
-  // can be attempted.
-  //   younger_handles_promotion_failure
-  // is true if the younger generation handles a promotion
-  // failure.
-  virtual bool promotion_attempt_is_safe(size_t promotion_in_bytes,
-    bool younger_handles_promotion_failure) const;
+  // might be attempted in the worst case.
+  virtual bool promotion_attempt_is_safe(size_t max_promotion_in_bytes) const;
 
   // For a non-young generation, this interface can be used to inform a
   // generation that a promotion attempt into that generation failed.
@@ -358,6 +354,16 @@
     return (full || should_allocate(word_size, is_tlab));
   }
 
+  // Returns true if the collection is likely to be safely
+  // completed. Even if this method returns true, a collection
+  // may not be guaranteed to succeed, and the system should be
+  // able to safely unwind and recover from that failure, albeit
+  // at some additional cost.
+  virtual bool collection_attempt_is_safe() {
+    guarantee(false, "Are you sure you want to call this method?");
+    return true;
+  }
+
   // Perform a garbage collection.
   // If full is true attempt a full garbage collection of this generation.
   // Otherwise, attempting to (at least) free enough space to support an
--- a/src/share/vm/memory/tenuredGeneration.cpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/memory/tenuredGeneration.cpp	Sat Oct 23 23:03:49 2010 -0700
@@ -419,29 +419,16 @@
 void TenuredGeneration::verify_alloc_buffers_clean() {}
 #endif // SERIALGC
 
-bool TenuredGeneration::promotion_attempt_is_safe(
-    size_t max_promotion_in_bytes,
-    bool younger_handles_promotion_failure) const {
-
-  bool result = max_contiguous_available() >= max_promotion_in_bytes;
-
-  if (younger_handles_promotion_failure && !result) {
-    result = max_contiguous_available() >=
-      (size_t) gc_stats()->avg_promoted()->padded_average();
-    if (PrintGC && Verbose && result) {
-      gclog_or_tty->print_cr("TenuredGeneration::promotion_attempt_is_safe"
-                  " contiguous_available: " SIZE_FORMAT
-                  " avg_promoted: " SIZE_FORMAT,
-                  max_contiguous_available(),
-                  gc_stats()->avg_promoted()->padded_average());
-    }
-  } else {
-    if (PrintGC && Verbose) {
-      gclog_or_tty->print_cr("TenuredGeneration::promotion_attempt_is_safe"
-                  " contiguous_available: " SIZE_FORMAT
-                  " promotion_in_bytes: " SIZE_FORMAT,
-                  max_contiguous_available(), max_promotion_in_bytes);
-    }
+bool TenuredGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
+  size_t available = max_contiguous_available();
+  size_t av_promo  = (size_t)gc_stats()->avg_promoted()->padded_average();
+  bool   res = (available >= av_promo) || (available >= max_promotion_in_bytes);
+  if (PrintGC && Verbose) {
+    gclog_or_tty->print_cr(
+      "Tenured: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT"),"
+      "max_promo("SIZE_FORMAT")",
+      res? "":" not", available, res? ">=":"<",
+      av_promo, max_promotion_in_bytes);
   }
-  return result;
+  return res;
 }
--- a/src/share/vm/memory/tenuredGeneration.hpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/memory/tenuredGeneration.hpp	Sat Oct 23 23:03:49 2010 -0700
@@ -101,8 +101,7 @@
 
   virtual void update_gc_stats(int level, bool full);
 
-  virtual bool promotion_attempt_is_safe(size_t max_promoted_in_bytes,
-    bool younger_handles_promotion_failure) const;
+  virtual bool promotion_attempt_is_safe(size_t max_promoted_in_bytes) const;
 
   void verify_alloc_buffers_clean();
 };
--- a/src/share/vm/runtime/arguments.cpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/runtime/arguments.cpp	Sat Oct 23 23:03:49 2010 -0700
@@ -185,6 +185,10 @@
                            JDK_Version::jdk_update(6,18), JDK_Version::jdk(7) },
   { "UseDepthFirstScavengeOrder",
                            JDK_Version::jdk_update(6,22), JDK_Version::jdk(7) },
+  { "HandlePromotionFailure",
+                           JDK_Version::jdk_update(6,24), JDK_Version::jdk(8) },
+  { "MaxLiveObjectEvacuationRatio",
+                           JDK_Version::jdk_update(6,24), JDK_Version::jdk(8) },
   { NULL, JDK_Version(0), JDK_Version(0) }
 };
 
@@ -1722,8 +1726,6 @@
     status = false;
   }
 
-  status = status && verify_percentage(MaxLiveObjectEvacuationRatio,
-                              "MaxLiveObjectEvacuationRatio");
   status = status && verify_percentage(AdaptiveSizePolicyWeight,
                               "AdaptiveSizePolicyWeight");
   status = status && verify_percentage(AdaptivePermSizeWeight, "AdaptivePermSizeWeight");
--- a/src/share/vm/runtime/globals.hpp	Thu Oct 21 17:29:24 2010 -0700
+++ b/src/share/vm/runtime/globals.hpp	Sat Oct 23 23:03:49 2010 -0700
@@ -1786,10 +1786,6 @@
   notproduct(bool, GCALotAtAllSafepoints, false,                            \
           "Enforce ScavengeALot/GCALot at all potential safepoints")        \
                                                                             \
-  product(bool, HandlePromotionFailure, true,                               \
-          "The youngest generation collection does not require "            \
-          "a guarantee of full promotion of all live objects.")             \
-                                                                            \
   product(bool, PrintPromotionFailure, false,                               \
           "Print additional diagnostic information following "              \
           " promotion failure")                                             \
@@ -3003,9 +2999,6 @@
   product(intx, NewRatio, 2,                                                \
           "Ratio of new/old generation sizes")                              \
                                                                             \
-  product(uintx, MaxLiveObjectEvacuationRatio, 100,                         \
-          "Max percent of eden objects that will be live at scavenge")      \
-                                                                            \
   product_pd(uintx, NewSizeThreadIncrease,                                  \
           "Additional size added to desired new generation size per "       \
           "non-daemon thread (in bytes)")                                   \