From 2b123a1a09e94e02148157cdafd261f06b534940 Mon Sep 17 00:00:00 2001 From: Athira Rajeev Date: Sun, 7 Jun 2026 19:32:45 +0530 Subject: [PATCH] tools/perf/sched: Update process names of processes in zombie state for both -s and -S options 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. Acked-by: Namhyung Kim Tested-by: Venkat Rao Bagalkote Signed-off-by: Athira Rajeev Signed-off-by: Namhyung Kim --- tools/perf/builtin-sched.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c index ae033ffd1079..6e0d8f4d270e 100644 --- a/tools/perf/builtin-sched.c +++ b/tools/perf/builtin-sched.c @@ -2270,12 +2270,6 @@ static void timehist_print_sample(struct perf_sched *sched, printf(" "); } - if (!thread__comm_set(thread)) { - const char *prev_comm = perf_sample__strval(sample, "prev_comm"); - - thread__set_comm(thread, prev_comm, sample->time); - } - printf(" %-*s ", comm_width, timehist_get_commstr(thread)); if (sched->show_prio) @@ -2981,6 +2975,16 @@ static int timehist_sched_change_event(const struct perf_tool *tool, thread__zput(itr->last_thread); } + /* + * 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 = perf_sample__strval(sample, "prev_comm"); + + thread__set_comm(thread, prev_comm, sample->time); + } + if (!sched->summary_only) timehist_print_sample(sched, sample, &al, thread, t, state); }