From: Athira Rajeev <atrajeev@linux•ibm.com>
To: acme@kernel•org, jolsa@kernel•org, adrian.hunter@intel•com,
mpetlan@redhat•com, tmricht@linux•ibm.com, maddy@linux•ibm.com,
irogers@google•com, namhyung@kernel•org
Cc: linux-perf-users@vger•kernel.org, linuxppc-dev@lists•ozlabs.org,
atrajeev@linux•ibm.com, hbathini@linux•vnet.ibm.com,
Tejas.Manhas1@ibm•com, Tanushree.Shah@ibm•com,
Shivani.Nittor@ibm•com
Subject: [PATCH] tools/perf/sched: Update process names of processes in zombie state for both -s and -S options
Date: Sun, 26 Apr 2026 15:09:30 +0530 [thread overview]
Message-ID: <20260426093930.47809-1-atrajeev@linux.ibm.com> (raw)
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
next reply other threads:[~2026-04-26 9:39 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-26 9:39 Athira Rajeev [this message]
2026-04-27 5:56 ` [PATCH] tools/perf/sched: Update process names of processes in zombie state for both -s and -S options Namhyung Kim
2026-05-21 8:32 ` Athira Rajeev
2026-05-21 14:17 ` Arnaldo Carvalho de Melo
2026-06-04 14:17 ` Arnaldo Carvalho de Melo
2026-06-04 15:08 ` Athira Rajeev
2026-06-04 15:26 ` Arnaldo Carvalho de Melo
2026-04-27 6:43 ` Venkat
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