From: Arnaldo Carvalho de Melo <acme@redhat.com>
To: Milian Wolff <milian.wolff@kdab.com>
Cc: ahmadkhorrami <ahmadkhorrami@ut.ac.ir>,
Jiri Olsa <jolsa@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Linux-trace Users <linux-trace-users@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
linux-trace-users-owner@vger.kernel.org,
Jin Yao <yao.jin@linux.intel.com>,
Namhyung Kim <namhyung@kernel.org>,
Andi Kleen <ak@linux.intel.com>
Subject: Re: Wrong Perf Backtraces
Date: Tue, 31 Mar 2020 13:10:02 -0300 [thread overview]
Message-ID: <20200331161002.GB23207@redhat.com> (raw)
In-Reply-To: <7774721.NyiUUSuA9g@agathebauer>
Em Tue, Mar 31, 2020 at 05:29:17PM +0200, Milian Wolff escreveu:
> On Dienstag, 31. März 2020 17:02:37 CEST ahmadkhorrami wrote:
> > Hi Milian,
> > Thanks for the detailed answer. Well, the bug you mentioned is bad news.
> > Because I sample using uppp. Perhaps this leads to these weird traces.
>
> Please read the full thread from here on:
>
> https://lkml.org/lkml/2018/11/2/86
>
> But as I said - it should be easy to check if this is really the issue are
> running into or not: Try to see if you see the problem when you sample without
> `ppp`. If not, then you can be pretty sure it's this issue. If you still see
> it, then it's something different.
>
> > Is this a purely software bug?
>
> I wouldn't call it that, personally. Rather, it's a limitation in the hardware
> and software. We would need something completely different to "fix" this, i.e.
> something like a deeper LBR. That's btw another alternative you could try:
> `perf record --call-graph lbr` and live with the short call stacks. But at
> least these should be correct (afaik). For me personally they are always far
> too short and thus not practical to use in reality.
Probably this may help:
From: Kan Liang <kan.liang@linux.intel.com>
Subject: [PATCH V4 00/17] Stitch LBR call stack (Perf Tools)
Date: Thu, 19 Mar 2020 13:25:00 -0700
https://lore.kernel.org/lkml/20200319202517.23423-1-kan.liang@linux.intel.com/
- Arnaldo
next prev parent reply other threads:[~2020-03-31 16:10 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <157597d74ff17f781d9de7e7e3defd13@ut.ac.ir>
2020-03-22 20:24 ` Wrong Perf Backtraces ahmadkhorrami
2020-03-23 0:34 ` Steven Rostedt
[not found] ` <21b3df4080709f193d62b159887e2a83@ut.ac.ir>
2020-03-23 8:49 ` Jiri Olsa
2020-03-23 10:03 ` ahmadkhorrami
2020-03-25 15:18 ` ahmadkhorrami
2020-03-25 15:46 ` Jiri Olsa
2020-03-25 18:54 ` ahmadkhorrami
2020-03-25 18:58 ` Arnaldo Carvalho de Melo
2020-03-25 19:10 ` ahmadkhorrami
2020-03-25 19:28 ` Arnaldo Carvalho de Melo
2020-03-25 20:01 ` ahmadkhorrami
2020-03-25 20:39 ` Jiri Olsa
2020-03-25 21:02 ` Jiri Olsa
2020-03-25 21:09 ` Steven Rostedt
2020-03-25 21:37 ` ahmadkhorrami
2020-03-25 21:46 ` Jiri Olsa
2020-03-25 22:21 ` ahmadkhorrami
2020-03-25 23:09 ` ahmadkhorrami
2020-03-26 9:59 ` Jiri Olsa
2020-03-26 13:20 ` ahmadkhorrami
2020-03-26 15:39 ` Jiri Olsa
2020-03-26 18:19 ` ahmadkhorrami
2020-03-26 18:21 ` ahmadkhorrami
2020-03-27 9:20 ` Jiri Olsa
2020-03-27 10:59 ` ahmadkhorrami
2020-03-27 11:04 ` ahmadkhorrami
2020-03-27 12:10 ` Milian Wolff
2020-03-27 12:58 ` ahmadkhorrami
2020-03-27 13:25 ` Milian Wolff
2020-03-27 13:33 ` ahmadkhorrami
2020-03-27 18:43 ` ahmadkhorrami
2020-03-27 22:37 ` Jiri Olsa
2020-03-27 23:12 ` ahmadkhorrami
2020-03-28 23:34 ` Jiri Olsa
2020-03-29 0:43 ` ahmadkhorrami
2020-03-29 1:16 ` ahmadkhorrami
2020-03-29 11:19 ` Jiri Olsa
2020-03-29 11:52 ` ahmadkhorrami
2020-03-29 12:08 ` Jiri Olsa
2020-03-29 12:39 ` ahmadkhorrami
2020-03-29 13:50 ` Milian Wolff
2020-03-29 14:23 ` ahmadkhorrami
2020-03-29 19:20 ` Jiri Olsa
2020-03-30 6:09 ` Milian Wolff
2020-03-30 13:07 ` Jiri Olsa
2020-03-30 13:49 ` ahmadkhorrami
2020-03-30 19:05 ` ahmadkhorrami
2020-03-30 21:05 ` debuginfod-based dwarf downloading, was " Frank Ch. Eigler
2020-03-31 9:26 ` Jiri Olsa
2020-03-31 14:00 ` Frank Ch. Eigler
2020-03-31 4:43 ` ahmadkhorrami
2020-03-31 9:30 ` Jiri Olsa
2020-03-31 11:53 ` ahmadkhorrami
2020-03-31 12:43 ` ahmadkhorrami
2020-03-31 13:20 ` Jiri Olsa
2020-03-31 13:39 ` ahmadkhorrami
2020-03-31 14:44 ` Milian Wolff
2020-03-31 15:02 ` ahmadkhorrami
2020-03-31 15:05 ` ahmadkhorrami
2020-03-31 15:29 ` Milian Wolff
2020-03-31 16:10 ` Arnaldo Carvalho de Melo [this message]
2020-03-31 19:20 ` ahmadkhorrami
2020-03-31 19:17 ` ahmadkhorrami
2020-03-31 20:57 ` ahmadkhorrami
2020-04-04 1:01 ` ahmadkhorrami
2020-04-11 16:42 ` ahmadkhorrami
2020-04-11 21:04 ` ahmadkhorrami
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