Re: [PATCH perf/core 00/22] perf refcnt debugger API and fixes

Wangnan (F)
2015-12-11T01:54:17Z

On 2015/12/10 23:12, 'Arnaldo Carvalho de Melo' wrote:

[SNIP]
> But this requires having these special refcnt__ routines, that will make
> tools/perf/ code patterns for reference counts look different that the
> refcount patterns in the kernel :-\
>
> And would be a requirement to change the observed workload :-\
>
> Is this _strictly_ required?

No. The requirement should be:

1. The create/get/put/delete functions are non-inline (because dwarf info
is not as reliable as symbol);
2. From their argument list, we can always get the variable we need (the
pointer of objects, the value of refcnt, etc.)

We don't have to use this refcnt things.

> Can't we, for a project like perf, where we
> know where some refcount (say, the one for 'struct thread') gets
> initialized, use that (thread__new()) and then hook into thread__get and
> thread__put and then use the destructor, thread__delete() as the place
> to dump leaks?
>

I think it is possible. If we can abstract a common pattern about it,
we can provide a perf subcommand which we can deal with generic alloc/free
pattern. I'll put it on my todo-list. Currently we are focusing on perf
daemonization.

Thank you.