linux-kernel - `perf report` about 1000x(!) slower in linux 4.15

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Message-ID: <c6aa77d0-3d0c-bd03-aaa9-f1c33eff277f@mpi-sws.org>
Date:   Tue, 20 Mar 2018 12:57:29 +0100
From:   Jan-Oliver Kaiser <janno@...-sws.org>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     linux-kernel@...r.kernel.org, milian.wolff@...b.com
Subject: `perf report` about 1000x(!) slower in linux 4.15

Dear perf maintainers,

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@...b.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?

Thanks,
Janno