[RFC] Enhanced Garbage Collection Probe Points

[Lukas Berk <lberk@redhat.com>]

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Hey,

I've been working on adding improved probe point within the garbage
collection system.  This will allow system administrators using various
tools to better analyze which garbage collection algorithms are
effective and java developers to better understand how (often) their
objects are being collected.

Specific probe points that I've aimed to include are:

- G1, concurrent mark sweep, parallel mark sweep, and tenured
  collections

- new generation definitions

- parallel scavenges

- parallel compaction

- object 'moves/resizes' between memory addresses

Please note that the attached patch should be appended to the
patch/systemtap.patch file.  Any feedback or suggestions would be
greatly appreciated.

Cheers,

Lukas

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diff -Nru openjdk.orig/hotspot/src/share/vm/memory/generation.cpp openjdk/hotspot/src/share/vm/memory/generation.cpp
--- openjdk.orig/hotspot/src/share/vm/memory/generation.cpp	2012-06-15 11:36:43.022837742 -0400
+++ openjdk/hotspot/src/share/vm/memory/generation.cpp	2012-06-15 13:35:39.714838057 -0400
@@ -40,6 +40,11 @@
 #include "runtime/java.hpp"
 #include "utilities/copy.hpp"
 #include "utilities/events.hpp"
+#include "utilities/dtrace.hpp"
+
+#ifndef USDT2
+  HS_DTRACE_PROBE_DECL4(provider, gc__collection__contig, bool, bool, size_t, bool);
+#endif /* !USDT2 */
 
 Generation::Generation(ReservedSpace rs, size_t initial_size, int level) :
   _level(level),
@@ -471,6 +476,9 @@
   ReferenceProcessorSpanMutator
     x(ref_processor(), GenCollectedHeap::heap()->reserved_region());
   GenMarkSweep::invoke_at_safepoint(_level, ref_processor(), clear_all_soft_refs);
+#ifndef USDT2
+  HS_DTRACE_PROBE4(hotspot, gc__collection__contig, full, clear_all_soft_refs, size, is_tlab);
+#endif  /* !USDT2 */
   SpecializationStats::print();
 }
 
diff -Nru openjdk.orig/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp openjdk/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp
--- openjdk.orig/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	2012-06-15 11:36:42.164837741 -0400
+++ openjdk/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	2012-06-15 13:35:45.224838227 -0400
@@ -55,6 +55,11 @@
 #include "runtime/vmThread.hpp"
 #include "services/memoryService.hpp"
 #include "services/runtimeService.hpp"
+#include "utilities/dtrace.hpp"
+
+#ifndef USDT2
+  HS_DTRACE_PROBE_DECL4(provider, gc__collection__contig, bool, bool, size_t, bool);
+#endif /* !USDT2 */
 
 // statics
 CMSCollector* ConcurrentMarkSweepGeneration::_collector = NULL;
@@ -1655,6 +1660,10 @@
                            size_t size,
                            bool   tlab)
 {
+
+#ifndef USDT2
+  HS_DTRACE_PROBE4(hotspot, gc__collection__contig, full, clear_all_soft_refs, size, tlab);
+#endif /* !USDT2 */
   if (!UseCMSCollectionPassing && _collectorState > Idling) {
     // For debugging purposes skip the collection if the state
     // is not currently idle
diff -Nru openjdk.orig/hotspot/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp openjdk/hotspot/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp
--- openjdk.orig/hotspot/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp	2012-06-15 11:36:41.816837741 -0400
+++ openjdk/hotspot/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp	2012-06-15 13:35:56.298821181 -0400
@@ -49,6 +49,11 @@
 #include "utilities/copy.hpp"
 #include "utilities/globalDefinitions.hpp"
 #include "utilities/workgroup.hpp"
+#include "utilities/dtrace.hpp"
+
+#ifndef USDT2
+  HS_DTRACE_PROBE_DECL4(provider, gc__collection__parnew, bool, bool, size_t, bool);
+#endif /* !USDT2 */
 
 #ifdef _MSC_VER
 #pragma warning( push )
@@ -878,6 +883,9 @@
                                bool   clear_all_soft_refs,
                                size_t size,
                                bool   is_tlab) {
+#ifndef USDT2
+  HS_DTRACE_PROBE4(hotspot, gc__collection__parnew, full, clear_all_soft_refs, size, is_tlab);
+#endif  /* !USDT2 */
   assert(full || size > 0, "otherwise we don't want to collect");
   GenCollectedHeap* gch = GenCollectedHeap::heap();
   assert(gch->kind() == CollectedHeap::GenCollectedHeap,
diff -Nru openjdk.orig/hotspot/src/share/vm/memory/defNewGeneration.cpp openjdk/hotspot/src/share/vm/memory/defNewGeneration.cpp
--- openjdk.orig/hotspot/src/share/vm/memory/defNewGeneration.cpp	2012-06-15 11:36:42.970837742 -0400
+++ openjdk/hotspot/src/share/vm/memory/defNewGeneration.cpp	2012-06-15 13:36:05.328838805 -0400
@@ -39,6 +39,11 @@
 #include "runtime/java.hpp"
 #include "utilities/copy.hpp"
 #include "utilities/stack.inline.hpp"
+#include "utilities/dtrace.hpp"
+
+#ifndef USDT2
+  HS_DTRACE_PROBE_DECL4(provider, gc__collection__defnew, bool, bool, size_t, bool);
+#endif /* !USDT2 */
 #ifdef TARGET_OS_FAMILY_linux
 # include "thread_linux.inline.hpp"
 #endif
@@ -528,6 +533,9 @@
                                bool   clear_all_soft_refs,
                                size_t size,
                                bool   is_tlab) {
+#ifndef USDT2
+  HS_DTRACE_PROBE4(hotspot, gc__collection__defnew, full, clear_all_soft_refs, size, is_tlab);
+#endif  /* !USDT2 */
   assert(full || size > 0, "otherwise we don't want to collect");
   GenCollectedHeap* gch = GenCollectedHeap::heap();
   _next_gen = gch->next_gen(this);
diff -Nru openjdk.orig/hotspot/src/share/vm/memory/tenuredGeneration.cpp openjdk/hotspot/src/share/vm/memory/tenuredGeneration.cpp
--- openjdk.orig/hotspot/src/share/vm/memory/tenuredGeneration.cpp	2012-06-15 11:36:43.016837742 -0400
+++ openjdk/hotspot/src/share/vm/memory/tenuredGeneration.cpp	2012-06-15 13:36:08.848839364 -0400
@@ -33,6 +33,11 @@
 #include "memory/tenuredGeneration.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/java.hpp"
+#include "utilities/dtrace.hpp"
+
+#ifndef USDT2
+  HS_DTRACE_PROBE_DECL4(provider, gc__collection__tenured, bool, bool, size_t, bool);
+#endif /* !USDT2 */
 
 TenuredGeneration::TenuredGeneration(ReservedSpace rs,
                                      size_t initial_byte_size, int level,
@@ -307,6 +312,9 @@
                                 size_t size,
                                 bool   is_tlab) {
   retire_alloc_buffers_before_full_gc();
+#ifndef USDT2
+  HS_DTRACE_PROBE4(hotspot, gc__collection__tenured, full, clear_all_soft_refs, size, is_tlab);
+#endif  /* !USDT2 */
   OneContigSpaceCardGeneration::collect(full, clear_all_soft_refs,
                                         size, is_tlab);
 }
diff -Nru openjdk.orig/hotspot/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp openjdk/hotspot/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp
--- openjdk.orig/hotspot/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp
+++ openjdk/hotspot/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp
@@ -40,8 +40,13 @@
 #include "runtime/handles.inline.hpp"
 #include "runtime/java.hpp"
 #include "runtime/vmThread.hpp"
+#include "utilities/dtrace.hpp"
 #include "utilities/vmError.hpp"
 
+#ifndef USDT2
+  HS_DTRACE_PROBE_DECL2(provider, gc__collection__parscavenge, *uintptr_t, *uintptr_t);
+#endif /* !USDT2 */
+
 PSYoungGen*  ParallelScavengeHeap::_young_gen = NULL;
 PSOldGen*    ParallelScavengeHeap::_old_gen = NULL;
 PSPermGen*   ParallelScavengeHeap::_perm_gen = NULL;
@@ -806,6 +811,9 @@
   }
 
   VM_ParallelGCSystemGC op(gc_count, full_gc_count, cause);
+#ifndef USDT2
+  HS_DTRACE_PROBE2(hotspot, gc__collection__parscavenge, &op, cause);
+#endif /* !USDT2 */
   VMThread::execute(&op);
 }

diff -Nru openjdk.orig/hotspot/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp openjdk/hotspot/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp
--- openjdk.orig/hotspot/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp	2012-06-26 09:24:22.472325287 -0400
+++ openjdk/hotspot/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp	2012-07-05 10:43:08.273800575 -0400
@@ -45,8 +45,13 @@
 #include "runtime/thread.hpp"
 #include "runtime/vmThread.hpp"
 #include "utilities/copy.hpp"
+#include "utilities/dtrace.hpp"
 #include "utilities/events.hpp"
 
+#ifndef USDT2
+  HS_DTRACE_PROBE_DECL2(provider, gc__collection__G1, *uintptr_t, *uintptr_t);
+#endif /* !USDT2 */
+
 class HeapRegion;
 
 void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp,
@@ -83,7 +88,9 @@
   // We should save the marks of the currently locked biased monitors.
   // The marking doesn't preserve the marks of biased objects.
   BiasedLocking::preserve_marks();
-
+#ifndef USDT2
+  HS_DTRACE_PROBE2(hotspot, gc__collection__G1, &sh, sh->gc_cause());
+#endif /* !USDT2 */
   mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
 
   mark_sweep_phase2();
diff -Nru openjdk.orig/hotspot/src/share/vm/compiler/oopMap.cpp openjdk/hotspot/src/share/vm/compiler/oopMap.cpp
--- openjdk.orig/hotspot/src/share/vm/compiler/oopMap.cpp	2012-06-26 09:24:22.390325184 -0400
+++ openjdk/hotspot/src/share/vm/compiler/oopMap.cpp	2012-07-06 10:12:44.981413003 -0400
@@ -33,9 +33,13 @@
 #include "memory/resourceArea.hpp"
 #include "runtime/frame.inline.hpp"
 #include "runtime/signature.hpp"
+#include "utilities/dtrace.hpp"
 #ifdef COMPILER1
 #include "c1/c1_Defs.hpp"
 #endif
+#ifndef USDT2
+  HS_DTRACE_PROBE_DECL1(provider, gc__collection__delete, *uintptr_t);
+#endif /* !USDT2 */
 
 // OopMapStream
 
@@ -677,6 +681,9 @@
                     " - Derived: " INTPTR_FORMAT "  Base: " INTPTR_FORMAT " (Offset: %d)",
           derived_loc, (address)*derived_loc, (address)base, offset);
     }
+#ifndef USDT2
+  HS_DTRACE_PROBE1(hotspot, gc__collection__delete, entry);
+#endif /* !USDT2 */
 
     // Delete entry
     delete entry;
--- openjdk.orig/hotspot/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp	2012-07-12 09:48:40.349999515 -0400
+++ openjdk/hotspot/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp	2012-07-19 18:38:07.560757426 -0400
@@ -53,11 +53,18 @@
 #include "runtime/vmThread.hpp"
 #include "services/management.hpp"
 #include "services/memoryService.hpp"
+#include "utilities/dtrace.hpp"
 #include "utilities/events.hpp"
 #include "utilities/stack.inline.hpp"
 
 #include <math.h>
 
+#ifndef USDT2
+  HS_DTRACE_PROBE_DECL2(provider, gc__collection__ParallelCompact__clear, *uintptr_t, *uintptr_t);
+  HS_DTRACE_PROBE_DECL2(provider, gc__collection__partest1, *uintptr_t, *uintptr_t);
+  HS_DTRACE_PROBE_DECL4(provider, gc__collection__move, *uintptr_t, *uintptr_t, *uintptr_t, *uintptr_t);
+#endif /* !USDT2 */
+
 // All sizes are in HeapWords.
 const size_t ParallelCompactData::Log2RegionSize  = 9; // 512 words
 const size_t ParallelCompactData::RegionSize      = (size_t)1 << Log2RegionSize;
@@ -433,6 +439,9 @@
 
 void ParallelCompactData::clear()
 {
+#ifndef USDT2
+  HS_DTRACE_PROBE2(hotspot, gc__collection__ParallelCompact__clear, &_region_data, _region_data->data_location());
+#endif /* !USDT2 */
   memset(_region_data, 0, _region_vspace->committed_size());
 }
 
@@ -1970,6 +1979,9 @@
          "should be in vm thread");
 
   ParallelScavengeHeap* heap = gc_heap();
+#ifndef USDT2
+  HS_DTRACE_PROBE2(hotspot, gc__collection__partest1, heap, heap->gc_cause());
+#endif /* !USDT2 */
   GCCause::Cause gc_cause = heap->gc_cause();
   assert(!heap->is_gc_active(), "not reentrant");
 
@@ -3376,6 +3388,9 @@
   // past the end of the partial object entering the region (if any).
   HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
   HeapWord* const new_top = _space_info[space_id].new_top();
+#ifndef USDT2
+  HS_DTRACE_PROBE4(hotspot, gc__collection__move, &beg_addr, &end_addr, &dest_addr, &new_top);
+#endif /* !USDT2 */
   assert(new_top >= dest_addr, "bad new_top value");
   const size_t words = pointer_delta(new_top, dest_addr);
 
--- openjdk.orig/hotspot/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp	2012-07-12 09:48:40.401000822 -0400
+++ openjdk/hotspot/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp	2012-07-19 18:36:43.787767399 -0400
@@ -51,8 +51,12 @@
 #include "runtime/vmThread.hpp"
 #include "runtime/vm_operations.hpp"
 #include "services/memoryService.hpp"
+#include "utilities/dtrace.hpp"
 #include "utilities/stack.inline.hpp"
 
+#ifndef USDT2
+  HS_DTRACE_PROBE_DECL2(provider, name, *uintptr_t, *uintptr_t);
+#endif /* !USDT2 */
 
 HeapWord*                  PSScavenge::_to_space_top_before_gc = NULL;
 int                        PSScavenge::_consecutive_skipped_scavenges = 0;
@@ -226,7 +230,13 @@
   PSAdaptiveSizePolicy* policy = heap->size_policy();
   IsGCActiveMark mark;
 
+#ifndef USDT2
+  HS_DTRACE_PROBE2(hotspot, gc__collection__PSScavenge__begin, *heap, heap->gc_cause());
+#endif /* !USDT2 */
   const bool scavenge_done = PSScavenge::invoke_no_policy();
+#ifndef USDT2
+  HS_DTRACE_PROBE2(hotspot, gc__collection__PSScavenge__end, *heap, heap->gc_cause());
+#endif /* !USDT2 */
   const bool need_full_gc = !scavenge_done ||
     policy->should_full_GC(heap->old_gen()->free_in_bytes());
   bool full_gc_done = false;
@@ -243,9 +253,27 @@
     const bool clear_all_softrefs = cp->should_clear_all_soft_refs();
 
     if (UseParallelOldGC) {
+#ifndef USDT2
+  HS_DTRACE_PROBE2(hotspot, gc__collection__PSParallelCompact__begin, *heap, heap->gc_cause()); 
+#endif /* !USDT2 */
+
       full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
+
+#ifndef USDT2
+  HS_DTRACE_PROBE2(hotspot, gc__collection__PSParallelCompact__end, *heap, heap->gc_cause());
+#endif /* !USDT2 */
+
     } else {
+
+#ifndef USDT2
+  HS_DTRACE_PROBE2(hotspot, gc__collection__PSMarkSweep__begin, *heap, heap->gc_cause());
+#endif /* !USDT2 */
+
       full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs);
+
+#ifndef USDT2
+  HS_DTRACE_PROBE2(hotspot, gc__collection__PSMarkSweep__end, *heap, heap->gc_cause());
+#endif /* !USDT2 */
     }
   }
 

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