changeset 4050:cea242198338

7200261: G1: Liveness counting inconsistencies during marking verification Summary: The clipping code in the routine that sets the bits for a range of cards, in the liveness accounting verification code was incorrect. It set all the bits in the card bitmap from the given starting index which would lead to spurious marking verification failures. Reviewed-by: brutisso, jwilhelm
author johnc
date Tue, 30 Oct 2012 11:45:51 -0700
parents a6f5d539ced4
children 1e5b6a49c06d
files src/share/vm/gc_implementation/g1/concurrentMark.cpp src/share/vm/gc_implementation/g1/concurrentMark.hpp src/share/vm/gc_implementation/g1/concurrentMark.inline.hpp
diffstat 3 files changed, 160 insertions(+), 87 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Tue Nov 06 15:16:32 2012 -0800
+++ b/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Tue Oct 30 11:45:51 2012 -0700
@@ -1190,28 +1190,14 @@
 // liveness counting data.
 class CMCountDataClosureBase: public HeapRegionClosure {
 protected:
+  G1CollectedHeap* _g1h;
   ConcurrentMark* _cm;
+  CardTableModRefBS* _ct_bs;
+
   BitMap* _region_bm;
   BitMap* _card_bm;
 
-  void set_card_bitmap_range(BitMap::idx_t start_idx, BitMap::idx_t last_idx) {
-    assert(start_idx <= last_idx, "sanity");
-
-    // Set the inclusive bit range [start_idx, last_idx].
-    // For small ranges (up to 8 cards) use a simple loop; otherwise
-    // use par_at_put_range.
-    if ((last_idx - start_idx) < 8) {
-      for (BitMap::idx_t i = start_idx; i <= last_idx; i += 1) {
-        _card_bm->par_set_bit(i);
-      }
-    } else {
-      assert(last_idx < _card_bm->size(), "sanity");
-      // Note BitMap::par_at_put_range() is exclusive.
-      _card_bm->par_at_put_range(start_idx, last_idx+1, true);
-    }
-  }
-
-  // It takes a region that's not empty (i.e., it has at least one
+  // Takes a region that's not empty (i.e., it has at least one
   // live object in it and sets its corresponding bit on the region
   // bitmap to 1. If the region is "starts humongous" it will also set
   // to 1 the bits on the region bitmap that correspond to its
@@ -1232,9 +1218,11 @@
   }
 
 public:
-  CMCountDataClosureBase(ConcurrentMark *cm,
+  CMCountDataClosureBase(G1CollectedHeap* g1h,
                          BitMap* region_bm, BitMap* card_bm):
-    _cm(cm), _region_bm(region_bm), _card_bm(card_bm) { }
+    _g1h(g1h), _cm(g1h->concurrent_mark()),
+    _ct_bs((CardTableModRefBS*) (g1h->barrier_set())),
+    _region_bm(region_bm), _card_bm(card_bm) { }
 };
 
 // Closure that calculates the # live objects per region. Used
@@ -1244,9 +1232,9 @@
   size_t _region_marked_bytes;
 
 public:
-  CalcLiveObjectsClosure(CMBitMapRO *bm, ConcurrentMark *cm,
+  CalcLiveObjectsClosure(CMBitMapRO *bm, G1CollectedHeap* g1h,
                          BitMap* region_bm, BitMap* card_bm) :
-    CMCountDataClosureBase(cm, region_bm, card_bm),
+    CMCountDataClosureBase(g1h, region_bm, card_bm),
     _bm(bm), _region_marked_bytes(0) { }
 
   bool doHeapRegion(HeapRegion* hr) {
@@ -1262,44 +1250,63 @@
       return false;
     }
 
-    HeapWord* nextTop = hr->next_top_at_mark_start();
-    HeapWord* start   = hr->bottom();
-
-    assert(start <= hr->end() && start <= nextTop && nextTop <= hr->end(),
+    HeapWord* ntams = hr->next_top_at_mark_start();
+    HeapWord* start = hr->bottom();
+
+    assert(start <= hr->end() && start <= ntams && ntams <= hr->end(),
            err_msg("Preconditions not met - "
-                   "start: "PTR_FORMAT", nextTop: "PTR_FORMAT", end: "PTR_FORMAT,
-                   start, nextTop, hr->end()));
+                   "start: "PTR_FORMAT", ntams: "PTR_FORMAT", end: "PTR_FORMAT,
+                   start, ntams, hr->end()));
 
     // Find the first marked object at or after "start".
-    start = _bm->getNextMarkedWordAddress(start, nextTop);
+    start = _bm->getNextMarkedWordAddress(start, ntams);
 
     size_t marked_bytes = 0;
 
-    while (start < nextTop) {
+    while (start < ntams) {
       oop obj = oop(start);
       int obj_sz = obj->size();
-      HeapWord* obj_last = start + obj_sz - 1;
+      HeapWord* obj_end = start + obj_sz;
 
       BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
-      BitMap::idx_t last_idx = _cm->card_bitmap_index_for(obj_last);
-
-      // Set the bits in the card BM for this object (inclusive).
-      set_card_bitmap_range(start_idx, last_idx);
+      BitMap::idx_t end_idx = _cm->card_bitmap_index_for(obj_end);
+
+      // Note: if we're looking at the last region in heap - obj_end
+      // could be actually just beyond the end of the heap; end_idx
+      // will then correspond to a (non-existent) card that is also
+      // just beyond the heap.
+      if (_g1h->is_in_g1_reserved(obj_end) && !_ct_bs->is_card_aligned(obj_end)) {
+        // end of object is not card aligned - increment to cover
+        // all the cards spanned by the object
+        end_idx += 1;
+      }
+
+      // Set the bits in the card BM for the cards spanned by this object.
+      _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
 
       // Add the size of this object to the number of marked bytes.
       marked_bytes += (size_t)obj_sz * HeapWordSize;
 
       // Find the next marked object after this one.
-      start = _bm->getNextMarkedWordAddress(obj_last + 1, nextTop);
+      start = _bm->getNextMarkedWordAddress(obj_end, ntams);
     }
 
     // Mark the allocated-since-marking portion...
     HeapWord* top = hr->top();
-    if (nextTop < top) {
-      BitMap::idx_t start_idx = _cm->card_bitmap_index_for(nextTop);
-      BitMap::idx_t last_idx = _cm->card_bitmap_index_for(top - 1);
-
-      set_card_bitmap_range(start_idx, last_idx);
+    if (ntams < top) {
+      BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
+      BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
+
+      // Note: if we're looking at the last region in heap - top
+      // could be actually just beyond the end of the heap; end_idx
+      // will then correspond to a (non-existent) card that is also
+      // just beyond the heap.
+      if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) {
+        // end of object is not card aligned - increment to cover
+        // all the cards spanned by the object
+        end_idx += 1;
+      }
+      _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
 
       // This definitely means the region has live objects.
       set_bit_for_region(hr);
@@ -1326,6 +1333,7 @@
 // regions during the STW cleanup pause.
 
 class VerifyLiveObjectDataHRClosure: public HeapRegionClosure {
+  G1CollectedHeap* _g1h;
   ConcurrentMark* _cm;
   CalcLiveObjectsClosure _calc_cl;
   BitMap* _region_bm;   // Region BM to be verified
@@ -1338,14 +1346,14 @@
   int _failures;
 
 public:
-  VerifyLiveObjectDataHRClosure(ConcurrentMark* cm,
+  VerifyLiveObjectDataHRClosure(G1CollectedHeap* g1h,
                                 BitMap* region_bm,
                                 BitMap* card_bm,
                                 BitMap* exp_region_bm,
                                 BitMap* exp_card_bm,
                                 bool verbose) :
-    _cm(cm),
-    _calc_cl(_cm->nextMarkBitMap(), _cm, exp_region_bm, exp_card_bm),
+    _g1h(g1h), _cm(g1h->concurrent_mark()),
+    _calc_cl(_cm->nextMarkBitMap(), g1h, exp_region_bm, exp_card_bm),
     _region_bm(region_bm), _card_bm(card_bm), _verbose(verbose),
     _exp_region_bm(exp_region_bm), _exp_card_bm(exp_card_bm),
     _failures(0) { }
@@ -1492,7 +1500,7 @@
   void work(uint worker_id) {
     assert(worker_id < _n_workers, "invariant");
 
-    VerifyLiveObjectDataHRClosure verify_cl(_cm,
+    VerifyLiveObjectDataHRClosure verify_cl(_g1h,
                                             _actual_region_bm, _actual_card_bm,
                                             _expected_region_bm,
                                             _expected_card_bm,
@@ -1522,10 +1530,10 @@
 
 class FinalCountDataUpdateClosure: public CMCountDataClosureBase {
  public:
-  FinalCountDataUpdateClosure(ConcurrentMark* cm,
+  FinalCountDataUpdateClosure(G1CollectedHeap* g1h,
                               BitMap* region_bm,
                               BitMap* card_bm) :
-    CMCountDataClosureBase(cm, region_bm, card_bm) { }
+    CMCountDataClosureBase(g1h, region_bm, card_bm) { }
 
   bool doHeapRegion(HeapRegion* hr) {
 
@@ -1549,12 +1557,30 @@
     if (ntams < top) {
       // This definitely means the region has live objects.
       set_bit_for_region(hr);
-    }
-
-    // Now set the bits for [ntams, top]
-    BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
-    BitMap::idx_t last_idx = _cm->card_bitmap_index_for(top);
-    set_card_bitmap_range(start_idx, last_idx);
+
+      // Now set the bits in the card bitmap for [ntams, top)
+      BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
+      BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
+
+      // Note: if we're looking at the last region in heap - top
+      // could be actually just beyond the end of the heap; end_idx
+      // will then correspond to a (non-existent) card that is also
+      // just beyond the heap.
+      if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) {
+        // end of object is not card aligned - increment to cover
+        // all the cards spanned by the object
+        end_idx += 1;
+      }
+
+      assert(end_idx <= _card_bm->size(),
+             err_msg("oob: end_idx=  "SIZE_FORMAT", bitmap size= "SIZE_FORMAT,
+                     end_idx, _card_bm->size()));
+      assert(start_idx < _card_bm->size(),
+             err_msg("oob: start_idx=  "SIZE_FORMAT", bitmap size= "SIZE_FORMAT,
+                     start_idx, _card_bm->size()));
+
+      _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
+     }
 
     // Set the bit for the region if it contains live data
     if (hr->next_marked_bytes() > 0) {
@@ -1594,7 +1620,7 @@
   void work(uint worker_id) {
     assert(worker_id < _n_workers, "invariant");
 
-    FinalCountDataUpdateClosure final_update_cl(_cm,
+    FinalCountDataUpdateClosure final_update_cl(_g1h,
                                                 _actual_region_bm,
                                                 _actual_card_bm);
 
@@ -2834,20 +2860,19 @@
 // Aggregate the counting data that was constructed concurrently
 // with marking.
 class AggregateCountDataHRClosure: public HeapRegionClosure {
+  G1CollectedHeap* _g1h;
   ConcurrentMark* _cm;
+  CardTableModRefBS* _ct_bs;
   BitMap* _cm_card_bm;
   size_t _max_task_num;
 
  public:
-  AggregateCountDataHRClosure(ConcurrentMark *cm,
+  AggregateCountDataHRClosure(G1CollectedHeap* g1h,
                               BitMap* cm_card_bm,
                               size_t max_task_num) :
-    _cm(cm), _cm_card_bm(cm_card_bm),
-    _max_task_num(max_task_num) { }
-
-  bool is_card_aligned(HeapWord* p) {
-    return ((uintptr_t(p) & (CardTableModRefBS::card_size - 1)) == 0);
-  }
+    _g1h(g1h), _cm(g1h->concurrent_mark()),
+    _ct_bs((CardTableModRefBS*) (g1h->barrier_set())),
+    _cm_card_bm(cm_card_bm), _max_task_num(max_task_num) { }
 
   bool doHeapRegion(HeapRegion* hr) {
     if (hr->continuesHumongous()) {
@@ -2878,16 +2903,23 @@
       return false;
     }
 
-    assert(is_card_aligned(start), "sanity");
-    assert(is_card_aligned(end), "sanity");
+    // 'start' should be in the heap.
+    assert(_g1h->is_in_g1_reserved(start) && _ct_bs->is_card_aligned(start), "sanity");
+    // 'end' *may* be just beyone the end of the heap (if hr is the last region)
+    assert(!_g1h->is_in_g1_reserved(end) || _ct_bs->is_card_aligned(end), "sanity");
 
     BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
     BitMap::idx_t limit_idx = _cm->card_bitmap_index_for(limit);
     BitMap::idx_t end_idx = _cm->card_bitmap_index_for(end);
 
-    // If ntams is not card aligned then we bump the index for
-    // limit so that we get the card spanning ntams.
-    if (!is_card_aligned(limit)) {
+    // If ntams is not card aligned then we bump card bitmap index
+    // for limit so that we get the all the cards spanned by
+    // the object ending at ntams.
+    // Note: if this is the last region in the heap then ntams
+    // could be actually just beyond the end of the the heap;
+    // limit_idx will then  correspond to a (non-existent) card
+    // that is also outside the heap.
+    if (_g1h->is_in_g1_reserved(limit) && !_ct_bs->is_card_aligned(limit)) {
       limit_idx += 1;
     }
 
@@ -2916,7 +2948,7 @@
 
         // BitMap::get_next_one_offset() can handle the case when
         // its left_offset parameter is greater than its right_offset
-        // parameter. If does, however, have an early exit if
+        // parameter. It does, however, have an early exit if
         // left_offset == right_offset. So let's limit the value
         // passed in for left offset here.
         BitMap::idx_t next_idx = MIN2(scan_idx + 1, limit_idx);
@@ -2952,7 +2984,7 @@
     _active_workers(n_workers) { }
 
   void work(uint worker_id) {
-    AggregateCountDataHRClosure cl(_cm, _cm_card_bm, _max_task_num);
+    AggregateCountDataHRClosure cl(_g1h, _cm_card_bm, _max_task_num);
 
     if (G1CollectedHeap::use_parallel_gc_threads()) {
       _g1h->heap_region_par_iterate_chunked(&cl, worker_id,
--- a/src/share/vm/gc_implementation/g1/concurrentMark.hpp	Tue Nov 06 15:16:32 2012 -0800
+++ b/src/share/vm/gc_implementation/g1/concurrentMark.hpp	Tue Oct 30 11:45:51 2012 -0700
@@ -806,7 +806,14 @@
     return _MARKING_VERBOSE_ && _verbose_level >= high_verbose;
   }
 
-  // Counting data structure accessors
+  // Liveness counting
+
+  // Utility routine to set an exclusive range of cards on the given
+  // card liveness bitmap
+  inline void set_card_bitmap_range(BitMap* card_bm,
+                                    BitMap::idx_t start_idx,
+                                    BitMap::idx_t end_idx,
+                                    bool is_par);
 
   // Returns the card number of the bottom of the G1 heap.
   // Used in biasing indices into accounting card bitmaps.
--- a/src/share/vm/gc_implementation/g1/concurrentMark.inline.hpp	Tue Nov 06 15:16:32 2012 -0800
+++ b/src/share/vm/gc_implementation/g1/concurrentMark.inline.hpp	Tue Oct 30 11:45:51 2012 -0700
@@ -28,6 +28,42 @@
 #include "gc_implementation/g1/concurrentMark.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 
+// Utility routine to set an exclusive range of cards on the given
+// card liveness bitmap
+inline void ConcurrentMark::set_card_bitmap_range(BitMap* card_bm,
+                                                  BitMap::idx_t start_idx,
+                                                  BitMap::idx_t end_idx,
+                                                  bool is_par) {
+
+  // Set the exclusive bit range [start_idx, end_idx).
+  assert((end_idx - start_idx) > 0, "at least one card");
+  assert(end_idx <= card_bm->size(), "sanity");
+
+  // Silently clip the end index
+  end_idx = MIN2(end_idx, card_bm->size());
+
+  // For small ranges use a simple loop; otherwise use set_range or
+  // use par_at_put_range (if parallel). The range is made up of the
+  // cards that are spanned by an object/mem region so 8 cards will
+  // allow up to object sizes up to 4K to be handled using the loop.
+  if ((end_idx - start_idx) <= 8) {
+    for (BitMap::idx_t i = start_idx; i < end_idx; i += 1) {
+      if (is_par) {
+        card_bm->par_set_bit(i);
+      } else {
+        card_bm->set_bit(i);
+      }
+    }
+  } else {
+    // Note BitMap::par_at_put_range() and BitMap::set_range() are exclusive.
+    if (is_par) {
+      card_bm->par_at_put_range(start_idx, end_idx, true);
+    } else {
+      card_bm->set_range(start_idx, end_idx);
+    }
+  }
+}
+
 // Returns the index in the liveness accounting card bitmap
 // for the given address
 inline BitMap::idx_t ConcurrentMark::card_bitmap_index_for(HeapWord* addr) {
@@ -35,7 +71,6 @@
   // by the card shift -- address 0 corresponds to card number 0.  One
   // must subtract the card num of the bottom of the heap to obtain a
   // card table index.
-
   intptr_t card_num = intptr_t(uintptr_t(addr) >> CardTableModRefBS::card_shift);
   return card_num - heap_bottom_card_num();
 }
@@ -46,8 +81,10 @@
                                          size_t* marked_bytes_array,
                                          BitMap* task_card_bm) {
   G1CollectedHeap* g1h = _g1h;
+  CardTableModRefBS* ct_bs = (CardTableModRefBS*) (g1h->barrier_set());
+
   HeapWord* start = mr.start();
-  HeapWord* last = mr.last();
+  HeapWord* end = mr.end();
   size_t region_size_bytes = mr.byte_size();
   uint index = hr->hrs_index();
 
@@ -61,24 +98,21 @@
   marked_bytes_array[index] += region_size_bytes;
 
   BitMap::idx_t start_idx = card_bitmap_index_for(start);
-  BitMap::idx_t last_idx = card_bitmap_index_for(last);
+  BitMap::idx_t end_idx = card_bitmap_index_for(end);
 
-  // The card bitmap is task/worker specific => no need to use 'par' routines.
-  // Set bits in the inclusive bit range [start_idx, last_idx].
-  //
-  // For small ranges use a simple loop; otherwise use set_range
-  // The range are the cards that are spanned by the object/region
-  // so 8 cards will allow objects/regions up to 4K to be handled
-  // using the loop.
-  if ((last_idx - start_idx) <= 8) {
-    for (BitMap::idx_t i = start_idx; i <= last_idx; i += 1) {
-     task_card_bm->set_bit(i);
-    }
-  } else {
-    assert(last_idx < task_card_bm->size(), "sanity");
-    // Note: BitMap::set_range() is exclusive.
-    task_card_bm->set_range(start_idx, last_idx+1);
+  // Note: if we're looking at the last region in heap - end
+  // could be actually just beyond the end of the heap; end_idx
+  // will then correspond to a (non-existent) card that is also
+  // just beyond the heap.
+  if (g1h->is_in_g1_reserved(end) && !ct_bs->is_card_aligned(end)) {
+    // end of region is not card aligned - incremement to cover
+    // all the cards spanned by the region.
+    end_idx += 1;
   }
+  // The card bitmap is task/worker specific => no need to use
+  // the 'par' BitMap routines.
+  // Set bits in the exclusive bit range [start_idx, end_idx).
+  set_card_bitmap_range(task_card_bm, start_idx, end_idx, false /* is_par */);
 }
 
 // Counts the given memory region in the task/worker counting