Re: [PATCH] tools/perf/sched: Update process names of processes in zombie state for both -s and -S options

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Thu, Jun 04, 2026 at 08:38:46PM +0530, Athira Rajeev wrote:
> > On 4 Jun 2026, at 7:47 PM, Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> > 
> > On Thu, May 21, 2026 at 11:17:58AM -0300, Arnaldo Carvalho de Melo wrote:
> >> On Thu, May 21, 2026 at 02:02:53PM +0530, Athira Rajeev wrote:
> >>>> On 27 Apr 2026, at 11:26 AM, Namhyung Kim <namhyung@kernel.org> wrote:
> >>>> On Sun, Apr 26, 2026 at 03:09:30PM +0530, Athira Rajeev wrote:
> >>>>> In redhat perftool testsuite, observed fail for this test:
> >>>>>   -- [ FAIL ] -- perf_sched :: test_timehist :: --with-summary (output regexp parsing)
> >>>>> 
> >>>>> This led to analysis of "perf sched timehist" summary options.
> >>>>> 
> >>>>> # perf sched record -a -o ./perf.data -- sleep 0.1
> >>>>>  This will record using perf sched record
> >>>>> 
> >>>>> perf sched timeliest has two options "-s" and "-S"
> >>>>> # perf sched -i ./perf.data timehist -S
> >>>>> -S : Captures summary also at the end
> >>>>> 
> >>>>> # perf sched -i ./perf.data timehist -s
> >>>>> -s : Captures only summary
> >>>>> 
> >>>>> The test saves -s result which has only summary and compares with
> >>>>> summary which comes at the end from -S . Since there is a difference
> >>>>> in these two, test fails.
> >>>>> 
> >>>>> Checking the behaviour change in -S and -s results, difference is:
> >>>>> 
> >>>>>                 rcu_sched[16]       2          4        0.013      0.001       0.003       0.006   33.23       0
> >>>>>              migration/11[73]       2          1        0.006      0.006       0.006       0.006    0.00       0
> >>>>>               migration/3[33]       2          1        0.006      0.006       0.006       0.006    0.00       0
> >>>>> -               :216753[216753]      -1          1        0.041      0.041       0.041       0.041    0.00       0
> >>>>> +                 sleep[216753]      -1          1        0.041      0.041       0.041       0.041    0.00       0
> >>>>>               migration/8[58]       2          1        0.005      0.005       0.005       0.005    0.00       0
> >>>>>           NetworkManager[811]       1          2        0.089      0.028       0.044       0.060   36.06       0
> >>>>>              migration/13[83]       2          1        0.005      0.005       0.005       0.005    0.00       0
> >>>>> 
> >>>>> Here 216753 is pid for sleep which is a zombie process. This is
> >>>>> happening in latest kernel due to an update in "-S" result.
> >>>>> In -S, the process name appears in the results "sleep[216753]",
> >>>>> where as in the -s, only pid is present in the summary result
> >>>>> ":216753[216753]".
> >>>>> 
> >>>>> After commit 39f473f6d0b2 ("perf sched timehist: decode process names
> >>>>> of processes in zombie state")
> >>>>> for -S option, if process name is using pid, it uses different way to
> >>>>> set it. So that we get the process name and not just Pid.
> >>>>> 
> >>>>> This change went in only for timehist_print_sample() function.
> >>>>> Add this improvement in generic place so that even -s option (which
> >>>>> captures summary) also will have meaningful information.
> >>>>> 
> >>>>> Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>
> >>>> 
> >>>> Acked-by: Namhyung Kim <namhyung@kernel.org>
> >>>> 
> >>>> Thanks,
> >>>> Namhyung
> >>> Hi,
> >>> 
> >>> Can we please have this pulled in, if the patch looks fine ?
> >> 
> >> Can you please check applying it on top of current perf-tools-next?
> > 
> > So, this seems to be also addressed by:
> > 
> > commit 39f473f6d0b24cf375893f2110b1cc9d8a079a42
> > Author: Anubhav Shelat <ashelat@redhat.com>
> > Date:   Wed Jul 16 16:39:15 2025 -0400
> > 
> >    perf sched timehist: decode process names of processes in zombie state
> > 
> >    Previously when running perf trace timehist --state, when recording
> >    processes in the zombie state the process name would not be decoded
> >    properly and appears with just the PID:
> > 
> >    1140057.412177 [0006]  Mutter Input Th[3139/3104]          0.956      0.019      0.041      S
> >    1140057.412222 [0012]  :1248612[1248612]                   0.000      0.000      0.332      Z
> >    1140057.412275 [0004]  <idle>                              0.052      0.052      0.953      I
> >    1140057.412284 [0008]  <idle>                              0.070      0.070      0.932      I
> >    1140057.412333 [0004]  KMS thread[3126/3104]               0.953      0.112      0.058      S
> > 
> >    Now some extra processing has been added to decode the process name:
> > 
> >    1140057.412177 [0006]  Mutter Input Th[3139/3104]          0.956      0.019      0.041      S
> >    1140057.412222 [0012]  sleep[1248612]                      0.000      0.000      0.332      Z
> >    1140057.412275 [0004]  <idle>                              0.052      0.052      0.953      I
> >    1140057.412284 [0008]  <idle>                              0.070      0.070      0.932      I
> >    1140057.412333 [0004]  KMS thread[3126/3104]               0.953      0.112      0.058      S
> > 
> >    Signed-off-by: Anubhav Shelat <ashelat@redhat.com>
> >    Link: https://lore.kernel.org/r/20250716203914.45772-2-ashelat@redhat.com
> >    Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > 
> > 
> > No? It is not applying to perf-tools-next, a quick look found the patch
> > above.
> 
> Hi Arnaldo
> 
> commit 39f473f6d0b2 ("perf sched timehist: decode process names
> of processes in zombie state”)
> added change for -S option. The patch I submitted is to add change in process name for “-s” option as well
> 
> I will check applying this on top of current perf-tools-next

Thanks for looking into this!

- Arnaldo