Cost of STACK object should be attributed to CCCS at time of thread creation

Right now, we always charge STACK objects to the SYSTEM cost centre. I think it makes more sense for us to charge them to the CCCS responsible for creating the thread: it’s more specific and we don’t really lose anything in the trade (it’s easy to ask for a per-closure-type profile). Here’s a strawman patch (obviously this doesn’t do anything when not compiling the profiling way.) Are there any objections?

diff --git a/rts/Threads.c b/rts/Threads.c
index b617616..76ac705 100644
--- a/rts/Threads.c
+++ b/rts/Threads.c
@@ -84,7 +84,7 @@ createThread(Capability *cap, W_ size)
     stack_size = round_to_mblocks(size - sizeofW(StgTSO));
     stack = (StgStack *)allocate(cap, stack_size);
     TICK_ALLOC_STACK(stack_size);
-    SET_HDR(stack, &stg_STACK_info, CCS_SYSTEM);
+    SET_HDR(stack, &stg_STACK_info, cap->r.rCCCS);
     stack->stack_size   = stack_size - sizeofW(StgStack);
     stack->sp           = stack->stack + stack->stack_size;
     stack->dirty        = 1;
@@ -575,7 +575,11 @@ threadStackOverflow (Capability *cap, StgTSO *tso)
                   chunk_size * sizeof(W_));
 
     new_stack = (StgStack*) allocate(cap, chunk_size);
-    SET_HDR(new_stack, &stg_STACK_info, CCS_SYSTEM);
+#ifdef PROFILING
+    SET_HDR(new_stack, &stg_STACK_info, old_stack->header.prof.ccs);
+#else
+    SET_HDR(new_stack, &stg_STACK_info, CCCS_SYSTEM);
+#endif
     TICK_ALLOC_STACK(chunk_size);
 
     new_stack->dirty = 0; // begin clean, we'll mark it dirty below

Trac metadata

Trac field	Value
Version	7.7
Type	Task
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Profiling
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