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

From: Arnaldo Carvalho de Melo <[email-masked]>
Date: Thu, 21 May 2026 11:17:58 -0300

On Thu, May 21, 2026 at 02:02:53PM +0530, Athira Rajeev wrote:
> > On 27 Apr 2026, at 11:26 AM, Namhyung Kim <[email-masked]> 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 <[email-masked]>
> > 
> > Acked-by: Namhyung Kim <[email-masked]>
> > 
> > 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?

Thanks,

- Arnaldo