diff --git a/mps/code/arenavm.c b/mps/code/arenavm.c
index b0d69b6b246..ddff692d28e 100644
--- a/mps/code/arenavm.c
+++ b/mps/code/arenavm.c
@@ -1102,7 +1102,8 @@ static Res vmArenaExtend(VMArena vmArena, Size size)
     break;
   } while(0);
 
-
+  EVENT3(vmArenaExtendStart, size, chunkSize,
+                             VMArenaReserved(VMArena2Arena(vmArena)));
   DIAG_SINGLEF(( "vmArenaExtend_Start", 
     "to accommodate size $W, try chunkSize $W", (WriteFW)size, (WriteFW)chunkSize,
     " (VMArenaReserved currently $W bytes)\n",
@@ -1129,6 +1130,8 @@ static Res vmArenaExtend(VMArena vmArena, Size size)
       /* remove slices, down to chunkHalf but no further */
       for(; chunkSize > chunkHalf; chunkSize -= sliceSize) {
         if(chunkSize < chunkMin) {
+          EVENT2(vmArenaExtendFail, chunkMin,
+                                    VMArenaReserved(VMArena2Arena(vmArena)));
           DIAG_SINGLEF(( "vmArenaExtend_FailMin", 
             "no remaining address-space chunk >= min($W)", (WriteFW)chunkMin,
             " (so VMArenaReserved remains $W bytes)\n",
@@ -1145,6 +1148,7 @@ static Res vmArenaExtend(VMArena vmArena, Size size)
 
 vmArenaExtend_Done:
 
+  EVENT2(vmArenaExtendDone, chunkSize, VMArenaReserved(VMArena2Arena(vmArena)));
   DIAG_SINGLEF(( "vmArenaExtend_Done",
     "Request for new chunk of VM $W bytes succeeded", (WriteFW)chunkSize,
     " (VMArenaReserved now $W bytes)\n", 
diff --git a/mps/code/eventdef.h b/mps/code/eventdef.h
index 27bb3bb6320..004ee6d9668 100644
--- a/mps/code/eventdef.h
+++ b/mps/code/eventdef.h
@@ -53,7 +53,7 @@
  */
  
 #define EventNameMAX ((size_t)19)
-#define EventCodeMAX ((EventCode)0x0069)
+#define EventCodeMAX ((EventCode)0x0071)
 
 /* FIXME: Work out why not-in-use events were not in use and restore or delete them. */
 
@@ -155,7 +155,17 @@
   EVENT(X, ArenaFree          , 0x0066,  TRUE, Arena) \
   EVENT(X, ArenaAllocFail     , 0x0067,  TRUE, Arena) \
   EVENT(X, SegMerge           , 0x0068,  TRUE, Seg) \
-  EVENT(X, SegSplit           , 0x0069,  TRUE, Seg)
+  EVENT(X, SegSplit           , 0x0069,  TRUE, Seg) \
+  /* Events converted from RHSK's diagnostics */ \
+  EVENT(X, vmArenaExtendStart , 0x006A,  TRUE, Arena) \
+  EVENT(X, vmArenaExtendFail  , 0x006B,  TRUE, Arena) \
+  EVENT(X, vmArenaExtendDone  , 0x006C,  TRUE, Arena) \
+  EVENT(X, MessagesDropped    , 0x006D,  TRUE, Arena) \
+  EVENT(X, MessagesExist      , 0x006E,  TRUE, Arena) \
+  EVENT(X, ChainCondemnAuto   , 0x006F,  TRUE, Trace) \
+  EVENT(X, TraceFindGrey      , 0x0070,  TRUE, Trace) \
+  EVENT(X, TraceBandAdvance   , 0x0071,  TRUE, Trace)
+  
 
 /* Remember to update EventNameMAX and EventCodeMAX in eventcom.h! 
    (These are checked in EventInit.) */
@@ -555,6 +565,41 @@
   PARAM(X,  2, P, segHi) \
   PARAM(X,  3, A, at)
 
+#define EVENT_vmArenaExtendStart_PARAMS(PARAM, X) \
+  PARAM(X,  0, W, size) /* size to accommodate */ \
+  PARAM(X,  1, W, chunkSize) /* chunkSize to try */ \
+  PARAM(X,  2, W, reserved) /* current VMArenaReserved */
+
+#define EVENT_vmArenaExtendFail_PARAMS(PARAM, X) \
+  PARAM(X,  0, W, chunkMin) /* no remaining address space chunk >= chunkMin */ \
+  PARAM(X,  1, W, reserved) /* current VMArenaReserved */
+
+#define EVENT_vmArenaExtendDone_PARAMS(PARAM, X) \
+  PARAM(X,  0, W, chunkSize) /* request succeeded for chunkSize bytes */ \
+  PARAM(X,  1, W, reserved) /* new VMArenaReserved */
+
+#define EVENT_MessagesDropped_PARAMS(PARAM, X) \
+  PARAM(X,  0, W, count) /* count of messages dropped */
+
+#define EVENT_MessagesExist_PARAMS(PARAM, X)
+
+#define EVENT_ChainCondemnAuto_PARAMS(PARAM, X) \
+  PARAM(X,  0, P, chain) /* chain with gens being condemned */ \
+  PARAM(X,  1, W, topCondemnedGenSerial) /* condemned gens [0..this] */ \
+  PARAM(X,  2, W, genCount) /* total gens in chain */
+
+#define EVENT_TraceFindGrey_PARAMS(PARAM, X) \
+  PARAM(X,  0, P, arena) \
+  PARAM(X,  1, W, ti) \
+  PARAM(X,  2, P, seg) \
+  PARAM(X,  3, W, rank)
+
+#define EVENT_TraceBandAdvance_PARAMS(PARAM, X) \
+  PARAM(X,  0, P, arena) \
+  PARAM(X,  1, W, ti) \
+  PARAM(X,  2, W, rank)
+
+
 #endif /* eventdef_h */
 
 /* C. COPYRIGHT AND LICENSE
diff --git a/mps/code/global.c b/mps/code/global.c
index bb666f4e44b..974ab9afffe 100644
--- a/mps/code/global.c
+++ b/mps/code/global.c
@@ -414,6 +414,7 @@ void GlobalsPrepareToDestroy(Globals arenaGlobals)
 
   /* report dropped messages (currently in diagnostic varieties only) */
   if(arena->droppedMessages > 0) {
+    EVENT1(MessagesDropped, arena->droppedMessages);
     DIAG_SINGLEF(( "GlobalsPrepareToDestroy_dropped",
       "arena->droppedMessages = $U", (WriteFU)arena->droppedMessages,
       NULL ));
@@ -425,6 +426,7 @@ void GlobalsPrepareToDestroy(Globals arenaGlobals)
   /* the message queue would have dangling pointers to messages */
   /* whose memory has been unmapped. */
   if(MessagePoll(arena)) {
+    EVENT0(MessagesExist);
     DIAG_SINGLEF(( "GlobalsPrepareToDestroy_queue",
       "Message queue not empty", NULL ));
   }
diff --git a/mps/code/locus.c b/mps/code/locus.c
index 22473026dc6..6ea5127ee12 100644
--- a/mps/code/locus.c
+++ b/mps/code/locus.c
@@ -295,6 +295,7 @@ Res ChainCondemnAuto(double *mortalityReturn, Chain chain, Trace trace)
     genNewSize = GenDescNewSize(gen);
   } while (genNewSize >= gen->capacity * (Size)1024);
   
+  EVENT3(ChainCondemnAuto, chain, topCondemnedGenSerial, chain->genCount);
   DIAG_SINGLEF(( "ChainCondemnAuto",
     "condemn gens [0..$U]", (WriteFU)topCondemnedGenSerial,
     " (of $U)", (WriteFU)chain->genCount,
diff --git a/mps/code/trace.c b/mps/code/trace.c
index c362a4809cf..9d2ea3af249 100644
--- a/mps/code/trace.c
+++ b/mps/code/trace.c
@@ -219,6 +219,7 @@ Bool traceBandAdvance(Trace trace)
     trace->band = RankAMBIG;
     return FALSE;
   }
+  EVENT3(TraceBandAdvance, trace->arena, trace->ti, trace->band);
   return TRUE;
 }
 
@@ -905,6 +906,7 @@ static Bool traceFindGrey(Seg *segReturn, Rank *rankReturn,
           }
           *segReturn = seg;
           *rankReturn = rank;
+          EVENT4(TraceFindGrey, arena, ti, seg, rank);
           DIAG( traceFindGrey_diag(TRUE, rank); );
           return TRUE;
         }