Re: `perf report` about 1000x(!) slower in linux 4.15

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Mar 20, 2018 at 12:57:29PM +0100, Jan-Oliver Kaiser escreveu:
> After upgrading my system to linux 4.15 (from 4.14), `perf report` became
> unusably slow. I estimate a decrease in performance by a factor of
> 100x-1000x. Some 21M perf.data files take about 30 seconds in the
> "Processing events" step.  `git bisect` points to
 
> commit d8a88dd243a170a226aba33e7c53704db2f82aa6 (HEAD, refs/bisect/bad)
> Author: Milian Wolff <milian.wolff@kdab.com>
>     perf util: Enable handling of inlined frames by default
 
> The slowdown can be worked around with `--no-inline`. If the slowdown is
> expected, I would suggest reverting the default setting here or maybe
> printing a warning if a lot of time is spent on this feature.
 
> Do you need any additional information about my system or the recorded data
> I am looking at?

Can you try with the latest perf tool? 

[acme@jouet perf]$ make perf-tarxz-src-pkg ; ls -la perf-4*
  TAR
  PERF_VERSION = 4.16.rc6.gecd380
-rw-rw-r--. 1 acme acme 1323568 Mar 20 10:30 perf-4.16.0-rc6.tar.xz
[acme@jouet perf]$

With a recently checked out kernel sources, or, as a convenience, I'm
pushing this to:

  http://vger.kernel.org/~acme/perf/perf-4.16.0-rc6.tar.xz

You just expand it and then:

[acme@jouet tmp]$ tar xf perf-4.16.0-rc6.tar.xz 
[acme@jouet tmp]$ cd perf-4.16.0-rc6/
[acme@jouet perf-4.16.0-rc6]$ make -C tools/perf install-bin


And check if the problem is present there as well.

If it is, please tell us what is your distro, the output of:

perf report --header-only

Thanks,

- Arnaldo