perf trace: Keep exited threads for summary

[ Upstream commit d29d92df410e2fb523f640478b18f70c1823e55e ]

Since 9ffa6c7512ca ("perf machine thread: Remove exited threads by
default") perf cleans exited threads up, but as said, sometimes they
are necessary to be kept. The mentioned commit does not cover all the
cases, we also need the information to construct the summary table in
perf-trace.

Before:
    # perf trace -s true

     Summary of events:

After:
    # perf trace -s -- true

     Summary of events:

     true (383382), 64 events, 91.4%

       syscall            calls  errors  total       min       avg       max       stddev
                                         (msec)    (msec)    (msec)    (msec)        (%)
       --------------- --------  ------ -------- --------- --------- ---------     ------
       mmap                   8      0     0.150     0.013     0.019     0.031     11.90%
       mprotect               3      0     0.045     0.014     0.015     0.017      6.47%
       openat                 2      0     0.014     0.006     0.007     0.007      9.73%
       munmap                 1      0     0.009     0.009     0.009     0.009      0.00%
       access                 1      1     0.009     0.009     0.009     0.009      0.00%
       pread64                4      0     0.006     0.001     0.001     0.002      4.53%
       fstat                  2      0     0.005     0.001     0.002     0.003     37.59%
       arch_prctl             2      1     0.003     0.001     0.002     0.002     25.91%
       read                   1      0     0.003     0.003     0.003     0.003      0.00%
       close                  2      0     0.003     0.001     0.001     0.001      3.86%
       brk                    1      0     0.002     0.002     0.002     0.002      0.00%
       rseq                   1      0     0.001     0.001     0.001     0.001      0.00%
       prlimit64              1      0     0.001     0.001     0.001     0.001      0.00%
       set_robust_list        1      0     0.001     0.001     0.001     0.001      0.00%
       set_tid_address        1      0     0.001     0.001     0.001     0.001      0.00%
       execve                 1      0     0.000     0.000     0.000     0.000      0.00%

[namhyung: simplified the condition]

Fixes: 9ffa6c7512ca ("perf machine thread: Remove exited threads by default")
Reported-by: Veronika Molnarova <vmolnaro@redhat.com>
Signed-off-by: Michael Petlan <mpetlan@redhat.com>
Link: https://lore.kernel.org/r/20240927151926.399474-1-mpetlan@redhat.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 8449f2beb54d74222365634df1cfc6d31bf1b9f6..19db23f78b199e8143f81f96f26746b0e3ea232e 100644 (file)
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -5038,6 +5038,10 @@ init_augmented_syscall_tp:
        if (trace.summary_only)
                trace.summary = trace.summary_only;
 
+       /* Keep exited threads, otherwise information might be lost for summary */
+       if (trace.summary)
+               symbol_conf.keep_exited_threads = true;
+
        if (output_name != NULL) {
                err = trace__open_output(&trace, output_name);
                if (err < 0) {