* Re: perf r5101c4 counter regression
2025-05-06 19:02 ` perf r5101c4 counter regression Salvatore Bonaccorso
@ 2025-05-08 20:56 ` Namhyung Kim
0 siblings, 0 replies; 2+ messages in thread
From: Namhyung Kim @ 2025-05-08 20:56 UTC (permalink / raw)
To: Salvatore Bonaccorso
Cc: Pasi Kallinen, 1104796, Peter Zijlstra, Ingo Molnar,
Arnaldo Carvalho de Melo, linux-perf-users, linux-kernel, stable,
regressions, Debian Bug Tracking System
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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