[llvm-dev] RFC: Sanitizer-based Heap Profiler

[Xinliang David Li via llvm-dev]

On Thu, Jul 8, 2021 at 9:04 AM Teresa Johnson <tejohnson at google.com> wrote:

>
>
> On Thu, Jul 8, 2021 at 8:56 AM Andrey Bokhanko <andreybokhanko at gmail.com>
> wrote:
>
>> On Thu, Jul 8, 2021 at 6:25 PM Teresa Johnson <tejohnson at google.com>
>> wrote:
>>
>>> Responding to this one first, I'll respond to your other email shortly.
>>> Initially we plan to provide hints to tcmalloc via new APIs to help it make
>>> allocation decisions (things like hotness and lifetime). The compiler will
>>> be responsible for adding these hints, using some method to disambiguate
>>> the calling context (e.g. via function cloning, new parameter, etc).
>>>
>> Sounds good -- thanks!
>>
>> (though this would increase code size and thus, instruction cache
>> pressure -- tsk, tsk... :-))
>>
>
> There are various methods for disambiguating the contexts (e.g. HALO
> inserts some instructions at a minimal number of callsites to do this), and
> I suspect a hybrid method will be best in practice. E.g. cloning for hot
> allocation contexts or callsites, and instructions or parameters or
> something else on colder allocation contexts and callsites, to balance the
> code size and dynamic instruction overheads.
>

Right -- static disambiguation is suitable for hot allocation sites which
are sensitive to any overhead added.

David

>
>
> --
> Teresa Johnson |  Software Engineer |  tejohnson at google.com |
>
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