* [PATCH] tools/perf/sched: Update process names of processes in zombie state for both -s and -S options
@ 2026-04-26 9:39 Athira Rajeev
2026-04-27 5:56 ` Namhyung Kim
2026-04-27 6:43 ` Venkat
0 siblings, 2 replies; 3+ messages in thread
From: Athira Rajeev @ 2026-04-26 9:39 UTC (permalink / raw)
To: acme, jolsa, adrian.hunter, mpetlan, tmricht, maddy, irogers,
namhyung
Cc: linux-perf-users, linuxppc-dev, atrajeev, hbathini, Tejas.Manhas1,
Tanushree.Shah, Shivani.Nittor
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>
---
tools/perf/builtin-sched.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 555247568e7a..ee1b89a6af50 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -2197,11 +2197,6 @@ static void timehist_print_sample(struct perf_sched *sched,
printf(" ");
}
- if (!thread__comm_set(thread)) {
- const char *prev_comm = evsel__strval(evsel, sample, "prev_comm");
- thread__set_comm(thread, prev_comm, sample->time);
- }
-
printf(" %-*s ", comm_width, timehist_get_commstr(thread));
if (sched->show_prio)
@@ -2890,6 +2885,15 @@ static int timehist_sched_change_event(const struct perf_tool *tool,
itr->last_thread = NULL;
}
+ /*
+ * If the process name is not set for the thread, use "prev_comm"
+ * to set it. Otherwise the sched summary will have just pid information
+ */
+ if (!thread__comm_set(thread)) {
+ const char *prev_comm = evsel__strval(evsel, sample, "prev_comm");
+ thread__set_comm(thread, prev_comm, sample->time);
+ }
+
if (!sched->summary_only)
timehist_print_sample(sched, evsel, sample, &al, thread, t, state);
}
--
2.47.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] tools/perf/sched: Update process names of processes in zombie state for both -s and -S options
2026-04-26 9:39 [PATCH] tools/perf/sched: Update process names of processes in zombie state for both -s and -S options Athira Rajeev
@ 2026-04-27 5:56 ` Namhyung Kim
2026-04-27 6:43 ` Venkat
1 sibling, 0 replies; 3+ messages in thread
From: Namhyung Kim @ 2026-04-27 5:56 UTC (permalink / raw)
To: Athira Rajeev
Cc: acme, jolsa, adrian.hunter, mpetlan, tmricht, maddy, irogers,
linux-perf-users, linuxppc-dev, hbathini, Tejas.Manhas1,
Tanushree.Shah, Shivani.Nittor
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
> ---
> tools/perf/builtin-sched.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
> index 555247568e7a..ee1b89a6af50 100644
> --- a/tools/perf/builtin-sched.c
> +++ b/tools/perf/builtin-sched.c
> @@ -2197,11 +2197,6 @@ static void timehist_print_sample(struct perf_sched *sched,
> printf(" ");
> }
>
> - if (!thread__comm_set(thread)) {
> - const char *prev_comm = evsel__strval(evsel, sample, "prev_comm");
> - thread__set_comm(thread, prev_comm, sample->time);
> - }
> -
> printf(" %-*s ", comm_width, timehist_get_commstr(thread));
>
> if (sched->show_prio)
> @@ -2890,6 +2885,15 @@ static int timehist_sched_change_event(const struct perf_tool *tool,
> itr->last_thread = NULL;
> }
>
> + /*
> + * If the process name is not set for the thread, use "prev_comm"
> + * to set it. Otherwise the sched summary will have just pid information
> + */
> + if (!thread__comm_set(thread)) {
> + const char *prev_comm = evsel__strval(evsel, sample, "prev_comm");
> + thread__set_comm(thread, prev_comm, sample->time);
> + }
> +
> if (!sched->summary_only)
> timehist_print_sample(sched, evsel, sample, &al, thread, t, state);
> }
> --
> 2.47.3
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] tools/perf/sched: Update process names of processes in zombie state for both -s and -S options
2026-04-26 9:39 [PATCH] tools/perf/sched: Update process names of processes in zombie state for both -s and -S options Athira Rajeev
2026-04-27 5:56 ` Namhyung Kim
@ 2026-04-27 6:43 ` Venkat
1 sibling, 0 replies; 3+ messages in thread
From: Venkat @ 2026-04-27 6:43 UTC (permalink / raw)
To: Athira Rajeev
Cc: acme, jolsa, adrian.hunter, mpetlan, tmricht, maddy, irogers,
namhyung, linux-perf-users, linuxppc-dev, hbathini, Tejas.Manhas1,
Tanushree.Shah, Shivani.Nittor
> On 26 Apr 2026, at 3:09 PM, Athira Rajeev <atrajeev@linux.ibm.com> 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>
> ---
Tested this patch, by applying on top of mainline kernel.
WithOut Fix:
# ./perf sched -i perf.data timehist -s
Samples of sched_switch event do not have callchains.
Runtime summary
comm parent sched-in run-time min-run avg-run max-run stddev migrations
(count) (msec) (msec) (msec) (msec) %
---------------------------------------------------------------------------------------------------------------------
migration/14[88] 2 1 0.006 0.006 0.006 0.006 0.00 0
migration/6[48] 2 1 0.008 0.008 0.008 0.008 0.00 0
rcu_preempt[16] 2 7 0.042 0.003 0.006 0.014 23.80 0
migration/11[73] 2 1 0.010 0.010 0.010 0.010 0.00 0
migration/3[33] 2 1 0.009 0.009 0.009 0.009 0.00 0
sshd-session[384033] 384025 4 0.104 0.023 0.026 0.032 8.14 0
kworker/u68:3-e[316378] 2 1 0.003 0.003 0.003 0.003 0.00 0
kcompactd3[114] 2 1 0.003 0.003 0.003 0.003 0.00 0
migration/8[58] 2 1 0.012 0.012 0.012 0.012 0.00 0
migration/13[83] 2 1 0.008 0.008 0.008 0.008 0.00 0
migration/5[43] 2 1 0.007 0.007 0.007 0.007 0.00 0
migration/0[19] 2 1 0.010 0.010 0.010 0.010 0.00 0
migration/10[68] 2 1 0.007 0.007 0.007 0.007 0.00 0
ksoftirqd/5[44] 2 1 0.184 0.184 0.184 0.184 0.00 0
migration/2[28] 2 1 0.008 0.008 0.008 0.008 0.00 0
kworker/4:0-mm_[383676] 2 1 0.013 0.013 0.013 0.013 0.00 0
perf[390116] 384034 17 0.065 0.000 0.003 0.065 100.00 0
xfsaild/dm-2[861] 2 1 0.008 0.008 0.008 0.008 0.00 0
migration/15[93] 2 1 0.009 0.009 0.009 0.009 0.00 0
:390117[390117] -1 1 0.124 0.124 0.124 0.124 0.00 0
kworker/9:4-mm_[390101] 2 1 0.069 0.069 0.069 0.069 0.00 0
migration/7[53] 2 1 0.008 0.008 0.008 0.008 0.00 0
kworker/5:0-xfs[390077] 2 1 0.015 0.015 0.015 0.015 0.00 0
migration/12[78] 2 1 0.007 0.007 0.007 0.007 0.00 0
migration/4[38] 2 1 0.005 0.005 0.005 0.005 0.00 0
NetworkManager[903] 1 4 0.275 0.032 0.068 0.105 29.66 0
migration/1[23] 2 1 0.010 0.010 0.010 0.010 0.00 0
migration/9[63] 2 1 0.011 0.011 0.011 0.011 0.00 0
With FIX:
# ./perf sched -i perf.data timehist -s
Samples of sched_switch event do not have callchains.
Runtime summary
comm parent sched-in run-time min-run avg-run max-run stddev migrations
(count) (msec) (msec) (msec) (msec) %
---------------------------------------------------------------------------------------------------------------------
migration/14[88] 2 1 0.006 0.006 0.006 0.006 0.00 0
migration/6[48] 2 1 0.008 0.008 0.008 0.008 0.00 0
rcu_preempt[16] 2 7 0.042 0.003 0.006 0.014 23.80 0
migration/11[73] 2 1 0.010 0.010 0.010 0.010 0.00 0
migration/3[33] 2 1 0.009 0.009 0.009 0.009 0.00 0
sshd-session[384033] 384025 4 0.104 0.023 0.026 0.032 8.14 0
kworker/u68:3-e[316378] 2 1 0.003 0.003 0.003 0.003 0.00 0
kcompactd3[114] 2 1 0.003 0.003 0.003 0.003 0.00 0
migration/8[58] 2 1 0.012 0.012 0.012 0.012 0.00 0
migration/13[83] 2 1 0.008 0.008 0.008 0.008 0.00 0
migration/5[43] 2 1 0.007 0.007 0.007 0.007 0.00 0
migration/0[19] 2 1 0.010 0.010 0.010 0.010 0.00 0
migration/10[68] 2 1 0.007 0.007 0.007 0.007 0.00 0
ksoftirqd/5[44] 2 1 0.184 0.184 0.184 0.184 0.00 0
migration/2[28] 2 1 0.008 0.008 0.008 0.008 0.00 0
kworker/4:0-mm_[383676] 2 1 0.013 0.013 0.013 0.013 0.00 0
perf[390116] 384034 17 0.065 0.000 0.003 0.065 100.00 0
xfsaild/dm-2[861] 2 1 0.008 0.008 0.008 0.008 0.00 0
migration/15[93] 2 1 0.009 0.009 0.009 0.009 0.00 0
sleep[390117] -1 1 0.124 0.124 0.124 0.124 0.00 0
kworker/9:4-mm_[390101] 2 1 0.069 0.069 0.069 0.069 0.00 0
migration/7[53] 2 1 0.008 0.008 0.008 0.008 0.00 0
kworker/5:0-xfs[390077] 2 1 0.015 0.015 0.015 0.015 0.00 0
migration/12[78] 2 1 0.007 0.007 0.007 0.007 0.00 0
migration/4[38] 2 1 0.005 0.005 0.005 0.005 0.00 0
NetworkManager[903] 1 4 0.275 0.032 0.068 0.105 29.66 0
migration/1[23] 2 1 0.010 0.010 0.010 0.010 0.00 0
migration/9[63] 2 1 0.011 0.011 0.011 0.011 0.00 0
Please add below tag.
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Regards,
Venkat.
> tools/perf/builtin-sched.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
> index 555247568e7a..ee1b89a6af50 100644
> --- a/tools/perf/builtin-sched.c
> +++ b/tools/perf/builtin-sched.c
> @@ -2197,11 +2197,6 @@ static void timehist_print_sample(struct perf_sched *sched,
> printf(" ");
> }
>
> - if (!thread__comm_set(thread)) {
> - const char *prev_comm = evsel__strval(evsel, sample, "prev_comm");
> - thread__set_comm(thread, prev_comm, sample->time);
> - }
> -
> printf(" %-*s ", comm_width, timehist_get_commstr(thread));
>
> if (sched->show_prio)
> @@ -2890,6 +2885,15 @@ static int timehist_sched_change_event(const struct perf_tool *tool,
> itr->last_thread = NULL;
> }
>
> + /*
> + * If the process name is not set for the thread, use "prev_comm"
> + * to set it. Otherwise the sched summary will have just pid information
> + */
> + if (!thread__comm_set(thread)) {
> + const char *prev_comm = evsel__strval(evsel, sample, "prev_comm");
> + thread__set_comm(thread, prev_comm, sample->time);
> + }
> +
> if (!sched->summary_only)
> timehist_print_sample(sched, evsel, sample, &al, thread, t, state);
> }
> --
> 2.47.3
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-04-26 9:39 [PATCH] tools/perf/sched: Update process names of processes in zombie state for both -s and -S options Athira Rajeev
2026-04-27 5:56 ` Namhyung Kim
2026-04-27 6:43 ` Venkat
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