Add new eventlog events for various heap and GC statistics

They cover much the same info as is available via the GHC.Stats module
or via the '+RTS -s' textual output, but via the eventlog and with a
better sampling frequency.

We have three new generic heap info events and two very GHC-specific
ones. (The hope is the general ones are usable by other implementations
that use the same eventlog system, or indeed not so sensitive to changes
in GHC itself.)

The general ones are:

 * total heap mem allocated since prog start, on a per-HEC basis
 * current size of the heap (MBlocks reserved from OS for the heap)
 * current size of live data in the heap

Currently these are all emitted by GHC at GC time (live data only at
major GC).

The GHC specific ones are:

 * an event giving various static heap paramaters:
   * number of generations (usually 2)
   * max size if any
   * nursary size
   * MBlock and block sizes
 * a event emitted on each GC containing:
   * GC generation (usually just 0,1)
   * total bytes copied
   * bytes lost to heap slop and fragmentation
   * the number of threads in the parallel GC (1 for serial)
   * the maximum number of bytes copied by any par GC thread
   * the total number of bytes copied by all par GC threads
     (these last three can be used to calculate an estimate of the
      work balance in parallel GCs)

11 files changed, 386 insertions, 15 deletions

diff --git a/includes/rts/EventLogFormat.h b/includes/rts/EventLogFormat.h
index afa1961a36..94f781dcb5 100644
--- a/includes/rts/EventLogFormat.h
+++ b/includes/rts/EventLogFormat.h
@@ -147,8 +147,18 @@
 #define EVENT_CAP_DELETE          46 /* (cap)                  */
 #define EVENT_CAP_DISABLE         47 /* (cap)                  */
 #define EVENT_CAP_ENABLE          48 /* (cap)                  */
-
-/* Range 49 - 59 is available for new GHC and common events */
+#define EVENT_HEAP_ALLOCATED      49 /* (heap_capset, alloc_bytes) */
+#define EVENT_HEAP_SIZE           50 /* (heap_capset, size_bytes) */
+#define EVENT_HEAP_LIVE           51 /* (heap_capset, live_bytes) */
+#define EVENT_HEAP_INFO_GHC       52 /* (heap_capset, n_generations,
+                                         max_heap_size, alloc_area_size,
+                                         mblock_size, block_size) */
+#define EVENT_GC_STATS_GHC        53 /* (heap_capset, generation,
+                                         copied_bytes, slop_bytes, frag_bytes,
+                                         par_n_threads,
+                                         par_max_copied, par_tot_copied) */
+
+/* Range 54 - 59 is available for new GHC and common events */
 
 /* Range 60 - 80 is used by eden for parallel tracing
  * see http://www.mathematik.uni-marburg.de/~eden/
@@ -161,7 +171,7 @@
  * ranges higher than this are reserved but not currently emitted by ghc.
  * This must match the size of the EventDesc[] array in EventLog.c
  */
-#define NUM_GHC_EVENT_TAGS        49
+#define NUM_GHC_EVENT_TAGS        54
 
 #if 0  /* DEPRECATED EVENTS: */
 /* we don't actually need to record the thread, it's implicit */
diff --git a/rts/RtsFlags.c b/rts/RtsFlags.c
index 5afaf4914b..320a1b2350 100644
--- a/rts/RtsFlags.c
+++ b/rts/RtsFlags.c
@@ -305,7 +305,7 @@ usage_text[] = {
 #  endif
 "             where [flags] can contain:",
 "                s    scheduler events",
-"                g    GC events",
+"                g    GC and heap events",
 "                p    par spark events (sampled)",
 "                f    par spark events (full detail)",
 "                u    user events (emitted from Haskell code)",
diff --git a/rts/RtsProbes.d b/rts/RtsProbes.d
index 0921c98397..8d24f3a9ca 100644
--- a/rts/RtsProbes.d
+++ b/rts/RtsProbes.d
@@ -55,6 +55,11 @@ provider HaskellEvent {
   probe gc__idle (EventCapNo);
   probe gc__work (EventCapNo);
   probe gc__done (EventCapNo);
+  probe gc__stats (CapsetID, StgWord, StgWord, StgWord, StgWord, StgWord, StgWord, StgWord);
+  probe heap__info (CapsetID, StgWord, StgWord, StgWord, StgWord, StgWord);
+  probe heap__allocated (EventCapNo, CapsetID, StgWord64);
+  probe heap__size (CapsetID, StgWord);
+  probe heap__live (CapsetID, StgWord);
 
   /* capability events */
   probe startup (EventCapNo);
diff --git a/rts/Stats.c b/rts/Stats.c
index 2277958557..a7335531ce 100644
--- a/rts/Stats.c
+++ b/rts/Stats.c
@@ -330,9 +330,9 @@ stat_gcWorkerThreadDone (gc_thread *gct STG_UNUSED)
    -------------------------------------------------------------------------- */
 
 void
-stat_endGC (gc_thread *gct,
-            lnat alloc, lnat live, lnat copied, nat gen,
-            lnat par_max_copied, lnat par_tot_copied, lnat slop)
+stat_endGC (Capability *cap, gc_thread *gct,
+            lnat alloc, lnat live, lnat copied, lnat slop, nat gen,
+            nat par_n_threads, lnat par_max_copied, lnat par_tot_copied)
 {
     if (RtsFlags.GcFlags.giveStats != NO_GC_STATS ||
         RtsFlags.ProfFlags.doHeapProfile)
@@ -388,9 +388,26 @@ stat_endGC (gc_thread *gct,
             lnat n;
             for (n = 0; n < n_capabilities; n++) {
                 tot_alloc += capabilities[n].total_allocated;
+                traceEventHeapAllocated(&capabilities[n],
+                                        CAPSET_HEAP_DEFAULT,
+                                        capabilities[n].total_allocated * sizeof(W_));
             }
             ASSERT(GC_tot_alloc == tot_alloc);
         }
+        traceEventHeapSize(cap,
+	                   CAPSET_HEAP_DEFAULT,
+			   mblocks_allocated * MBLOCK_SIZE_W * sizeof(W_));
+        traceEventGcStats(cap,
+                          CAPSET_HEAP_DEFAULT,
+                          gen,
+                          copied * sizeof(W_),
+                          slop   * sizeof(W_),
+                          /* current loss due to fragmentation */
+                          (mblocks_allocated * BLOCKS_PER_MBLOCK - n_alloc_blocks)
+                                 * BLOCK_SIZE_W * sizeof(W_),
+                          par_n_threads,
+                          par_max_copied * sizeof(W_),
+                          par_tot_copied * sizeof(W_));
 
 	if (gen == RtsFlags.GcFlags.generations-1) { /* major GC? */
 	    if (live > max_residency) {
@@ -399,6 +416,9 @@ stat_endGC (gc_thread *gct,
             current_residency = live;
 	    residency_samples++;
 	    cumulative_residency += live;
+	    traceEventHeapLive(cap, 
+    	    	    	       CAPSET_HEAP_DEFAULT,
+	                       live * sizeof(W_));
 	}
 
         if (slop > max_slop) max_slop = slop;
diff --git a/rts/Stats.h b/rts/Stats.h
index 83b2cb6998..63a1801236 100644
--- a/rts/Stats.h
+++ b/rts/Stats.h
@@ -19,9 +19,9 @@ void      stat_startInit(void);
 void      stat_endInit(void);
 
 void      stat_startGC(struct gc_thread_ *gct);
-void      stat_endGC  (struct gc_thread_ *gct, lnat alloc, lnat live, 
-		       lnat copied, nat gen,
-                       lnat max_copied, lnat avg_copied, lnat slop);
+void      stat_endGC  (Capability *cap, struct gc_thread_ *gct,
+                       lnat alloc, lnat live, lnat copied, lnat slop, nat gen,
+                       nat n_gc_threads, lnat par_max_copied, lnat par_tot_copied);
 
 void stat_gcWorkerThreadStart (struct gc_thread_ *gct);
 void stat_gcWorkerThreadDone  (struct gc_thread_ *gct);
diff --git a/rts/Trace.c b/rts/Trace.c
index 70eb6ce506..f597726f90 100644
--- a/rts/Trace.c
+++ b/rts/Trace.c
@@ -98,6 +98,9 @@ void initTracing (void)
     TRACE_gc =
         RtsFlags.TraceFlags.gc ||
         RtsFlags.DebugFlags.gc;
+    if (TRACE_gc && RtsFlags.GcFlags.giveStats == NO_GC_STATS) {
+        RtsFlags.GcFlags.giveStats = COLLECT_GC_STATS;
+    }
 
     TRACE_spark_sampled =
         RtsFlags.TraceFlags.sparks_sampled;
@@ -301,6 +304,44 @@ void traceGcEvent_ (Capability *cap, EventTypeNum tag)
     }
 }
 
+void traceHeapEvent_ (Capability   *cap,
+                      EventTypeNum  tag,
+                      CapsetID      heap_capset,
+                      lnat          info1)
+{
+    /* no stderr equivalent for these ones */
+    postHeapEvent(cap, tag, heap_capset, info1);
+}
+
+void traceEventHeapInfo_ (CapsetID    heap_capset,
+                          nat         gens,
+                          lnat        maxHeapSize,
+                          lnat        allocAreaSize,
+                          lnat        mblockSize,
+                          lnat        blockSize)
+{
+    /* no stderr equivalent for this one */
+    postEventHeapInfo(heap_capset, gens,
+                      maxHeapSize, allocAreaSize,
+                      mblockSize, blockSize);
+}
+
+void traceEventGcStats_  (Capability *cap,
+                          CapsetID    heap_capset,
+                          nat         gen,
+                          lnat        copied,
+                          lnat        slop,
+                          lnat        fragmentation,
+                          nat         par_n_threads,
+                          lnat        par_max_copied,
+                          lnat        par_tot_copied)
+{
+    /* no stderr equivalent for this one */
+    postEventGcStats(cap, heap_capset, gen,
+                     copied, slop, fragmentation,
+                     par_n_threads, par_max_copied, par_tot_copied);
+}
+
 void traceCapEvent (Capability   *cap,
                     EventTypeNum  tag)
 {
diff --git a/rts/Trace.h b/rts/Trace.h
index dcb0b00621..18856d9721 100644
--- a/rts/Trace.h
+++ b/rts/Trace.h
@@ -37,8 +37,9 @@ typedef StgWord16 CapsetType;
 enum CapsetType { CapsetTypeCustom = CAPSET_TYPE_CUSTOM,
                   CapsetTypeOsProcess = CAPSET_TYPE_OSPROCESS,
                   CapsetTypeClockdomain = CAPSET_TYPE_CLOCKDOMAIN };
-#define CAPSET_OSPROCESS_DEFAULT 0
-#define CAPSET_CLOCKDOMAIN_DEFAULT 1
+#define CAPSET_OSPROCESS_DEFAULT   ((CapsetID)0)
+#define CAPSET_HEAP_DEFAULT        ((CapsetID)0)   /* reusing the same capset */
+#define CAPSET_CLOCKDOMAIN_DEFAULT ((CapsetID)1)
 
 // -----------------------------------------------------------------------------
 // Message classes
@@ -113,6 +114,35 @@ void traceSchedEvent_ (Capability *cap, EventTypeNum tag,
 void traceGcEvent_ (Capability *cap, EventTypeNum tag);
 
 /* 
+ * Record a heap event
+ */
+#define traceHeapEvent(cap, tag, heap_capset, info1) \
+    if (RTS_UNLIKELY(TRACE_gc)) { \
+        traceHeapEvent_(cap, tag, heap_capset, info1);  \
+    }
+void traceHeapEvent_ (Capability   *cap,
+                      EventTypeNum  tag,
+                      CapsetID      heap_capset,
+                      lnat          info1);
+
+void traceEventHeapInfo_ (CapsetID    heap_capset,
+                          nat         gens,
+                          lnat        maxHeapSize,
+                          lnat        allocAreaSize,
+                          lnat        mblockSize,
+                          lnat        blockSize);
+
+void traceEventGcStats_  (Capability *cap,
+                          CapsetID    heap_capset,
+                          nat         gen,
+                          lnat        copied,
+                          lnat        slop,
+                          lnat        fragmentation,
+                          nat         par_n_threads,
+                          lnat        par_max_copied,
+                          lnat        par_tot_copied);
+
+/* 
  * Record a spark event
  */
 #define traceSparkEvent(cap, tag)         \
@@ -227,6 +257,13 @@ void traceSparkCounters_ (Capability *cap,
 #define traceSchedEvent(cap, tag, tso, other) /* nothing */
 #define traceSchedEvent2(cap, tag, tso, other, info) /* nothing */
 #define traceGcEvent(cap, tag) /* nothing */
+#define traceEventGcStats_(cap, heap_capset, gen, \
+                           copied, slop, fragmentation, \
+                           par_n_threads, par_max_copied, par_tot_copied) /* nothing */
+#define traceHeapEvent(cap, tag, heap_capset, info1) /* nothing */
+#define traceEventHeapInfo_(heap_capset, gens, \
+                            maxHeapSize, allocAreaSize, \
+                            mblockSize, blockSize) /* nothing */
 #define traceSparkEvent(cap, tag) /* nothing */
 #define traceSparkEvent2(cap, tag, other) /* nothing */
 #define traceCap(class, cap, msg, ...) /* nothing */
@@ -302,6 +339,31 @@ INLINE_HEADER void dtraceStartup (int num_caps) {
     HASKELLEVENT_GC_WORK(cap)
 #define dtraceGcDone(cap)                               \
     HASKELLEVENT_GC_DONE(cap)
+#define dtraceEventGcStats(heap_capset, gens,           \
+                           copies, slop, fragmentation, \
+                           par_n_threads,               \
+                           par_max_copied,              \
+                           par_tot_copied)              \
+    HASKELLEVENT_GC_STATS(heap_capset, gens,            \
+                           copies, slop, fragmentation, \
+                           par_n_threads,               \
+                           par_max_copied,              \
+                           par_tot_copied)              \
+#define dtraceHeapInfo(heap_capset, gens,               \
+                       maxHeapSize, allocAreaSize,      \
+                       mblockSize, blockSize)           \
+    HASKELLEVENT_HEAP_INFO(heap_capset, gens,           \
+                           maxHeapSize, allocAreaSize,  \
+                           mblockSize, blockSize)
+#define dtraceEventHeapAllocated(cap, heap_capset,      \
+                                 allocated)             \
+    HASKELLEVENT_HEAP_ALLOCATED(cap, heap_capset,       \
+                                allocated)
+#define dtraceEventHeapSize(heap_capset, size)          \
+    HASKELLEVENT_HEAP_LIVE(heap_capset, size)
+#define dtraceEventHeapLive(heap_capset, live)          \
+    HASKELLEVENT_HEAP_LIVE(heap_capset, live)
+
 #define dtraceCapsetCreate(capset, capset_type)         \
     HASKELLEVENT_CAPSET_CREATE(capset, capset_type)
 #define dtraceCapsetDelete(capset)                      \
@@ -346,6 +408,18 @@ INLINE_HEADER void dtraceStartup (int num_caps STG_UNUSED) {};
 #define dtraceGcIdle(cap)                               /* nothing */
 #define dtraceGcWork(cap)                               /* nothing */
 #define dtraceGcDone(cap)                               /* nothing */
+#define dtraceEventGcStats(heap_capset, gens,           \
+                           copies, slop, fragmentation, \
+                           par_n_threads,               \
+                           par_max_copied,              \
+                           par_tot_copied)              /* nothing */
+#define dtraceHeapInfo(heap_capset, gens,               \
+                       maxHeapSize, allocAreaSize,      \
+                       mblockSize, blockSize)           /* nothing */
+#define dtraceEventHeapAllocated(cap, heap_capset,      \
+                                 allocated)             /* nothing */
+#define dtraceEventHeapSize(heap_capset, size)          /* nothing */
+#define dtraceEventHeapLive(heap_capset, live)          /* nothing */
 #define dtraceCapCreate(cap)                            /* nothing */
 #define dtraceCapDelete(cap)                            /* nothing */
 #define dtraceCapEnable(cap)                            /* nothing */
@@ -511,6 +585,70 @@ INLINE_HEADER void traceEventGcDone(Capability *cap STG_UNUSED)
     dtraceGcDone((EventCapNo)cap->no);
 }
 
+INLINE_HEADER void traceEventGcStats(Capability *cap            STG_UNUSED,
+                                     CapsetID    heap_capset    STG_UNUSED,
+                                     nat         gen            STG_UNUSED,
+                                     lnat        copied         STG_UNUSED,
+                                     lnat        slop           STG_UNUSED,
+                                     lnat        fragmentation  STG_UNUSED,
+                                     nat         par_n_threads  STG_UNUSED,
+                                     lnat        par_max_copied STG_UNUSED,
+                                     lnat        par_tot_copied STG_UNUSED)
+{
+    if (RTS_UNLIKELY(TRACE_gc)) {
+        traceEventGcStats_(cap, heap_capset, gen,
+                           copied, slop, fragmentation,
+                           par_n_threads, par_max_copied, par_tot_copied);
+    }
+    dtraceEventGcStats(heap_capset, gens,
+                       copies, slop, fragmentation,
+                       par_n_threads, par_max_copied, par_tot_copied);
+}
+
+INLINE_HEADER void traceEventHeapInfo(CapsetID    heap_capset   STG_UNUSED,
+                                      nat         gens          STG_UNUSED,
+                                      lnat        maxHeapSize   STG_UNUSED,
+                                      lnat        allocAreaSize STG_UNUSED,
+                                      lnat        mblockSize    STG_UNUSED,
+                                      lnat        blockSize     STG_UNUSED)
+{
+    if (RTS_UNLIKELY(TRACE_gc)) {
+        traceEventHeapInfo_(heap_capset, gens,
+                            maxHeapSize, allocAreaSize,
+                            mblockSize, blockSize);
+    }
+    dtraceHeapInfo(heap_capset, gens,
+                   maxHeapSize, allocAreaSize,
+                   mblockSize, blockSize);
+}
+
+INLINE_HEADER void traceEventHeapAllocated(Capability *cap         STG_UNUSED,
+                                           CapsetID    heap_capset STG_UNUSED,
+                                           lnat        allocated   STG_UNUSED)
+{
+    traceHeapEvent(cap, EVENT_HEAP_ALLOCATED, heap_capset, allocated);
+    dtraceEventHeapAllocated((EventCapNo)cap->no, heap_capset, allocated);
+}
+
+INLINE_HEADER void traceEventHeapSize(Capability *cap         STG_UNUSED,
+                                      CapsetID    heap_capset STG_UNUSED,
+                                      lnat        heap_size   STG_UNUSED)
+{
+    traceHeapEvent(cap, EVENT_HEAP_SIZE, heap_capset, heap_size);
+    dtraceEventHeapSize(heap_capset, heap_size);
+}
+
+INLINE_HEADER void traceEventHeapLive(Capability *cap         STG_UNUSED,
+                                      CapsetID    heap_capset STG_UNUSED,
+                                      lnat        heap_live   STG_UNUSED)
+{
+    traceHeapEvent(cap, EVENT_HEAP_LIVE, heap_capset, heap_live);
+    dtraceEventHeapLive(heap_capset, heap_live);
+}
+
+/* TODO: at some point we should remove this event, it's covered by
+ * the cap create/delete events.
+ */
 INLINE_HEADER void traceEventStartup(void)
 {
     int n_caps;
diff --git a/rts/eventlog/EventLog.c b/rts/eventlog/EventLog.c
index 8009a38938..a43ebf789a 100644
--- a/rts/eventlog/EventLog.c
+++ b/rts/eventlog/EventLog.c
@@ -71,6 +71,11 @@ char *EventDesc[] = {
   [EVENT_GC_END]              = "Finished GC",
   [EVENT_REQUEST_SEQ_GC]      = "Request sequential GC",
   [EVENT_REQUEST_PAR_GC]      = "Request parallel GC",
+  [EVENT_GC_STATS_GHC]        = "GC statistics",
+  [EVENT_HEAP_INFO_GHC]       = "Heap static parameters",
+  [EVENT_HEAP_ALLOCATED]      = "Total heap mem ever allocated",
+  [EVENT_HEAP_SIZE]           = "Current heap size",
+  [EVENT_HEAP_LIVE]           = "Current heap live data",
   [EVENT_CREATE_SPARK_THREAD] = "Create spark thread",
   [EVENT_LOG_MSG]             = "Log message",
   [EVENT_USER_MSG]            = "User message",
@@ -358,6 +363,31 @@ initEventLogging(void)
             eventTypes[t].size = 7 * sizeof(StgWord64);
             break;
 
+        case EVENT_HEAP_ALLOCATED:    // (heap_capset, alloc_bytes)
+        case EVENT_HEAP_SIZE:         // (heap_capset, size_bytes)
+        case EVENT_HEAP_LIVE:         // (heap_capset, live_bytes)
+            eventTypes[t].size = sizeof(EventCapsetID) + sizeof(StgWord64);
+            break;
+
+        case EVENT_HEAP_INFO_GHC:     // (heap_capset, n_generations,
+                                      //  max_heap_size, alloc_area_size,
+                                      //  mblock_size, block_size)
+            eventTypes[t].size = sizeof(EventCapsetID)
+                               + sizeof(StgWord16)
+                               + sizeof(StgWord64) * 4;
+            break;
+
+        case EVENT_GC_STATS_GHC:      // (heap_capset, generation,
+                                      //  copied_bytes, slop_bytes, frag_bytes,
+                                      //  par_n_threads,
+                                      //  par_max_copied, par_tot_copied)
+            eventTypes[t].size = sizeof(EventCapsetID)
+                               + sizeof(StgWord16)
+                               + sizeof(StgWord64) * 3
+                               + sizeof(StgWord32)
+                               + sizeof(StgWord64) * 2;
+            break;
+
         case EVENT_BLOCK_MARKER:
             eventTypes[t].size = sizeof(StgWord32) + sizeof(EventTimestamp) + 
                 sizeof(EventCapNo);
@@ -783,6 +813,101 @@ void postWallClockTime (EventCapsetID capset)
     RELEASE_LOCK(&eventBufMutex);
 }
 
+/*
+ * Various GC and heap events
+ */
+void postHeapEvent (Capability    *cap,
+                    EventTypeNum   tag,
+                    EventCapsetID  heap_capset,
+                    lnat           info1)
+{
+    EventsBuf *eb;
+
+    eb = &capEventBuf[cap->no];
+
+    if (!hasRoomForEvent(eb, tag)) {
+        // Flush event buffer to make room for new event.
+        printAndClearEventBuf(eb);
+    }
+    
+    postEventHeader(eb, tag);
+
+    switch (tag) {
+    case EVENT_HEAP_ALLOCATED:     // (heap_capset, alloc_bytes)
+    case EVENT_HEAP_SIZE:          // (heap_capset, size_bytes)
+    case EVENT_HEAP_LIVE:          // (heap_capset, live_bytes)
+    {
+        postCapsetID(eb, heap_capset);
+        postWord64(eb,info1 /* alloc/size/live_bytes */);
+        break;
+    }
+
+    default:
+        barf("postHeapEvent: unknown event tag %d", tag);
+    }
+}
+
+void postEventHeapInfo (EventCapsetID heap_capset,
+                        nat           gens,
+                        lnat          maxHeapSize,
+                        lnat          allocAreaSize,
+                        lnat          mblockSize,
+                        lnat          blockSize)
+{
+    ACQUIRE_LOCK(&eventBufMutex);
+
+    if (!hasRoomForEvent(&eventBuf, EVENT_HEAP_INFO_GHC)) {
+        // Flush event buffer to make room for new event.
+        printAndClearEventBuf(&eventBuf);
+    }
+
+    postEventHeader(&eventBuf, EVENT_HEAP_INFO_GHC);
+    /* EVENT_HEAP_INFO_GHC (heap_capset, n_generations,
+                            max_heap_size, alloc_area_size,
+                            mblock_size, block_size) */
+    postCapsetID(&eventBuf, heap_capset);
+    postWord16(&eventBuf, gens);
+    postWord64(&eventBuf, maxHeapSize);
+    postWord64(&eventBuf, allocAreaSize);
+    postWord64(&eventBuf, mblockSize);
+    postWord64(&eventBuf, blockSize);
+
+    RELEASE_LOCK(&eventBufMutex);
+}
+
+void postEventGcStats  (Capability    *cap,
+                        EventCapsetID  heap_capset,
+                        nat            gen,
+                        lnat           copied,
+                        lnat           slop,
+                        lnat           fragmentation,
+                        nat            par_n_threads,
+                        lnat           par_max_copied,
+                        lnat           par_tot_copied)
+{
+    EventsBuf *eb;
+
+    eb = &capEventBuf[cap->no];
+
+    if (!hasRoomForEvent(eb, EVENT_GC_STATS_GHC)) {
+        // Flush event buffer to make room for new event.
+        printAndClearEventBuf(eb);
+    }
+    
+    postEventHeader(eb, EVENT_GC_STATS_GHC);
+    /* EVENT_GC_STATS_GHC (heap_capset, generation,
+                           copied_bytes, slop_bytes, frag_bytes,
+                           par_n_threads, par_max_copied, par_tot_copied) */
+    postCapsetID(eb, heap_capset);
+    postWord16(eb, gen);
+    postWord64(eb, copied);
+    postWord64(eb, slop);
+    postWord64(eb, fragmentation);
+    postWord32(eb, par_n_threads);
+    postWord64(eb, par_max_copied);
+    postWord64(eb, par_tot_copied);
+}
+
 void
 postEvent (Capability *cap, EventTypeNum tag)
 {
diff --git a/rts/eventlog/EventLog.h b/rts/eventlog/EventLog.h
index 6a3b32dad3..dadc6fa6d9 100644
--- a/rts/eventlog/EventLog.h
+++ b/rts/eventlog/EventLog.h
@@ -97,6 +97,31 @@ void postThreadLabel(Capability    *cap,
                      EventThreadID  id,
                      char          *label);
 
+/*
+ * Various GC and heap events
+ */
+void postHeapEvent (Capability    *cap,
+                    EventTypeNum   tag,
+                    EventCapsetID  heap_capset,
+                    StgWord        info1);
+
+void postEventHeapInfo (EventCapsetID heap_capset,
+                        nat           gens,
+                        lnat          maxHeapSize,
+                        lnat          allocAreaSize,
+                        lnat          mblockSize,
+                        lnat          blockSize);
+
+void postEventGcStats  (Capability    *cap,
+                        EventCapsetID  heap_capset,
+                        nat            gen,
+                        lnat           copied,
+                        lnat           slop,
+                        lnat           fragmentation,
+                        nat            par_n_threads,
+                        lnat           par_max_copied,
+                        lnat           par_tot_copied);
+
 #else /* !TRACING */
 
 INLINE_HEADER void postSchedEvent (Capability *cap  STG_UNUSED,
diff --git a/rts/sm/GC.c b/rts/sm/GC.c
index 8201a24e5b..055a1363ed 100644
--- a/rts/sm/GC.c
+++ b/rts/sm/GC.c
@@ -738,9 +738,9 @@ GarbageCollect (rtsBool force_major_gc,
 #endif
 
   // ok, GC over: tell the stats department what happened. 
-  stat_endGC(gct, allocated, live_words,
-             copied, N, par_max_copied, par_tot_copied,
-             live_blocks * BLOCK_SIZE_W - live_words /* slop */);
+  stat_endGC(cap, gct, allocated, live_words, copied,
+             live_blocks * BLOCK_SIZE_W - live_words /* slop */,
+             N, n_gc_threads, par_max_copied, par_tot_copied);
 
   // Guess which generation we'll collect *next* time
   initialise_N(force_major_gc);
diff --git a/rts/sm/Storage.c b/rts/sm/Storage.c
index 59ad231f34..4cd1bc99c9 100644
--- a/rts/sm/Storage.c
+++ b/rts/sm/Storage.c
@@ -186,6 +186,13 @@ initStorage (void)
   IF_DEBUG(gc, statDescribeGens());
 
   RELEASE_SM_LOCK;
+
+  traceEventHeapInfo(CAPSET_HEAP_DEFAULT,
+                     RtsFlags.GcFlags.generations,
+                     RtsFlags.GcFlags.maxHeapSize * BLOCK_SIZE_W * sizeof(W_),
+                     RtsFlags.GcFlags.minAllocAreaSize * BLOCK_SIZE_W * sizeof(W_),
+                     MBLOCK_SIZE_W * sizeof(W_),
+                     BLOCK_SIZE_W  * sizeof(W_));
 }
 
 void storageAddCapabilities (nat from, nat to)