ticky/cc profiling and heap checks

[Nicolas Frisby]

Moving all ticky bumps after the heapcheck did prevent the wiggling I
noticed.

Could you also weigh in on the location of the cost centre profiling
entries?

Thanks!


On Mon, Feb 18, 2013 at 2:19 PM, Simon Marlow <marlowsd at gmail.com> wrote:

> 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.
>
> Cheers,
>         Simon
>
>
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