Groups > linux.debian.bugs.dist > #1245263

Bug#1104796: perf r5101c4 counter regression

From	Namhyung Kim <namhyung@kernel.org>
Newsgroups	linux.debian.bugs.dist, linux.kernel, linux.debian.kernel
Subject	Bug#1104796: perf r5101c4 counter regression
Date	2025-05-08 23:10 +0200
Message-ID	<KKgFb-1HiO-1@gated-at.bofh.it> (permalink)
References	<KJtl7-1b1q-1@gated-at.bofh.it> <KJvPX-1cJ2-7@gated-at.bofh.it> <KJtl7-1b1q-1@gated-at.bofh.it> <KJvPX-1cJ2-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Cross-posted to 3 groups.

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Hello,

On Tue, May 06, 2025 at 09:02:20PM +0200, Salvatore Bonaccorso wrote:
> Hi,
> 
> Pasi Kallinen reported in Debian a regression with perf r5101c4
> counter, initially it was found in
> https://github.com/rr-debugger/rr/issues/3949 but said to be a kernel
> problem.

What's the '51' part?  I don't think it's defined.

  $ grep . -r /sys/bus/event_source/devices/cpu/format/
  /sys/bus/event_source/devices/cpu/format/event:config:0-7
  /sys/bus/event_source/devices/cpu/format/pc:config:19
  /sys/bus/event_source/devices/cpu/format/edge:config:18
  /sys/bus/event_source/devices/cpu/format/offcore_rsp:config1:0-63
  /sys/bus/event_source/devices/cpu/format/ldlat:config1:0-15
  /sys/bus/event_source/devices/cpu/format/inv:config:23
  /sys/bus/event_source/devices/cpu/format/umask:config:8-15
  /sys/bus/event_source/devices/cpu/format/frontend:config1:0-23
  /sys/bus/event_source/devices/cpu/format/cmask:config:24-31

Nothing for bit 16, 20 and 22 on the 'config' field.

Is it possible to fix rr to use a correct event encoding instead?

Thanks,
Namhyung

> 
> On Tue, May 06, 2025 at 07:18:39PM +0300, Pasi Kallinen wrote:
> > Package: src:linux
> > Version: 6.12.25-1
> > Severity: normal
> > X-Debbugs-Cc: debian-amd64@lists.debian.org, paxed@alt.org
> > User: debian-amd64@lists.debian.org
> > Usertags: amd64
> > 
> > Dear Maintainer,
> > 
> > perf stat -e r5101c4 true
> > 
> > reports "not supported".
> > 
> > The counters worked in kernel 6.11.10.
> > 
> > I first noticed this not working when updating to 6.12.22.
> > Booting back to 6.11.10, the counters work correctly.
> 
> Does this ring a bell?
> 
> Would you be able to bisect the changes to identify where the
> behaviour changed?
> 
> Regards,
> Salvatore

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Bug#1104796: perf r5101c4 counter regression Salvatore Bonaccorso <carnil@debian.org> - 2025-05-06 21:10 +0200
  Bug#1104796: perf r5101c4 counter regression Namhyung Kim <namhyung@kernel.org> - 2025-05-08 23:10 +0200

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