ticky/cc profiling and heap checks
marlowsd at gmail.com
Mon Feb 18 21:10:41 CET 2013
On 18/02/13 17:38, Nicolas Frisby wrote:
> Moving all ticky bumps after the heapcheck did prevent the wiggling I
> Could you also weigh in on the location of the cost centre profiling
The cost centre bumps should definitely be after the heap check too.
> On Mon, Feb 18, 2013 at 2:19 PM, Simon Marlow <marlowsd at gmail.com
> <mailto:marlowsd at gmail.com>> wrote:
> On 16/02/13 16:32, Nicolas Frisby wrote:
> I noticed some suspicious wiggling in my ticky reports' entry
> 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.
> 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.
> * 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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