linux-kernel - Re: Invalid event (cycles:pp) in per-thread mode, enable system wide with '-a'.

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Message-ID: <CAKwvOdm9SAQ5i74JUzWP4Q1WW3aHq+3Jo7hqfie+oMxjnKqxSA@mail.gmail.com>
Date:   Mon, 10 Jul 2023 14:22:11 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Ravi Bangoria <ravi.bangoria@....com>,
        Namhyung Kim <namhyung@...il.com>
Cc:     Stephane Eranian <eranian@...gle.com>,
        Slade Watkins <srw@...dewatkins.net>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ian Rogers <irogers@...gle.com>,
        Kees Cook <keescook@...omium.org>, sandipan.das@....com,
        Bill Wendling <morbo@...gle.com>,
        clang-built-linux <llvm@...ts.linux.dev>,
        Yonghong Song <yhs@...com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: Invalid event (cycles:pp) in per-thread mode, enable system wide
 with '-a'.

On Sun, Jun 25, 2023 at 10:45 PM Ravi Bangoria <ravi.bangoria@....com> wrote:
>
> Hi Nick,
>
> On 23-Jun-23 9:53 PM, Nick Desaulniers wrote:
> >>> On 12-Oct-22 3:02 AM, Nick Desaulniers wrote:
> > Hi Ravi,
> > Sorry, I'm not able to load a custom kernel image on my employer
> > provided workstation, and I never got approval to expense hardware for
> > testing this otherwise.
> >
> > Was there ever any update on this? I'm on 6.1.25 now and still cant run
> > $ perf record -e cycles:pp --call-graph lbr <any command to profile>
>
> Per-process precise sampling on AMD platforms should work from 6.2-rc1
> onward.

Ok, I can wait for my employer to ship 6.2 on our workstations.

> However, --call-graph=lbr is not supported on AMD (hw limitation).

On any AMD uarches? Is there an equivalent? LBR encoding is compact
which makes working it much faster than DWARF or stack frame
unwinding.
-- 
Thanks,
~Nick Desaulniers