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@xxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxx/ - Arnaldo
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