| From | Arnaldo Carvalho de Melo <> | Date | Wed, 24 Jul 2019 10:50:40 -0300 | Subject | Re: [RFC 00/79] perf tools: Initial libperf separation |
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Em Wed, Jul 24, 2019 at 07:42:50AM +0000, Song Liu escreveu: > > On Jul 21, 2019, at 4:23 AM, Jiri Olsa <jolsa@kernel.org> wrote:
> > we have long term goal to separate some of the perf functionality > > into library. This patchset is initial effort on separating some > > of the interface.
> > Currently only the basic counting interface is exported, it allows > > to: > > - create cpu/threads maps > > - create evlist/evsel objects > > - add evsel objects into evlist > > - open/close evlist/evsel objects > > - enable/disable events > > - read evsel counts > Based on my understanding, evsel and evlist are abstractions in > perf utilities. I think most other tools that use perf UAPIs are > not built based on these abstractions. I looked at a few internal > tools. Most of them just uses sys_perf_event_open() and struct > perf_event_attr. I am not sure whether these tools would adopt > libperf, as libperf changes their existing concepts/abstractions.
Right, and for now we're just trying to have something that is not so tied to perf and could possibly be useful outside tools/perf/ when the need arises for whatever new tool or pre-existing one.
There are features there that may be interesting to use outside perf, time will tell.
> > The initial effort was to have total separation of the objects > > from perf code, but it showed not to be a good way. The amount > > of changed code was too big with high chance for regressions, > > mainly because of the code embedding one of the above objects > > statically.
> > We took the other approach of sharing the objects/struct details > > within the perf and libperf code. This way we can keep perf > > functionality without any major changes and the libperf users > > are still separated from the object/struct details. We can move > > to total libperf's objects separation gradually in future. > I found some duplicated logic between libperf and perf, for > example, perf_evlist__open() and evlist__open(). Do we plan to > merge them in the future?
He is just slowly moving things to a public libperf while keeping perf working, in the end the goal is to have as much stuff that is not super specific to some of the existing perf tools (tools/perf/builtin-*.c) in libperf as possible.
It is still early in this effort, that is why he is still leaving it in tools/perf/lib/ and not in tools/lib/perf/ :-)
- Arnaldo
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