ticky/cc profiling and heap checks

Simon Marlow marlowsd at gmail.com
Mon Feb 18 15:19:41 CET 2013

On 16/02/13 16:32, Nicolas Frisby wrote:
> I noticed some suspicious wiggling in my ticky reports' entry counts.
> SPJ suggested they were due to the counter ticking before the heap
> check: if it fails, then it ticks again when we re-enter after the
> stg_gc function does its thing.
> After looking into it a bit further, I have a couple questions. Here's
> what I found.
>    * for functions (StgCmmBind.closureCodeBody), tickyEnterFun and
> enterCostCentreFun are before the heap check
>    * for thunks (StgCmmBind.thunkCode), tickyEnterThunk is before the
> heap check and enterCostCentreThunk is after.
> Questions:
>    * Does any object to me moving both ticky counters after the heap check?
>    * Is there a reason the two cost centre profiling entries are on
> opposite sides of the heap check?

It sounds wrong to me.  If you could clean this up that would be great. 
  These counters should never be bumped before the heap check, because 
if the heap check fails then the bumps will happen twice.


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