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Message-ID: <20250517163230.1237469-6-howardchu95@gmail.com>
Date: Sat, 17 May 2025 09:32:30 -0700
From: Howard Chu <howardchu95@...il.com>
To: acme@...nel.org
Cc: mingo@...hat.com,
namhyung@...nel.org,
mark.rutland@....com,
alexander.shishkin@...ux.intel.com,
jolsa@...nel.org,
irogers@...gle.com,
adrian.hunter@...el.com,
peterz@...radead.org,
kan.liang@...ux.intel.com,
linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org,
Howard Chu <howardchu95@...il.com>
Subject: [PATCH v1 5/5] perf test trace BTF: Use --sort-events in BTF general tests
Without the '--sort-events' flag, perf trace doesn't receive and process
events based on their arrival time, thus PERF_RECORD_COMM event that
assigns the correct comm to a PID, may be delivered and processed after
regular samples, causing trace outputs not having a 'comm', e.g.
'mv', instead, having the default PID placeholder, e.g. ':14514'.
Hopefully this answers Namhyung's question in [1].
You can simply justify the statement with this diff:
---8<---
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index edab0ff60b3c..f042afed5b74 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -4204,6 +4204,7 @@ static int trace__deliver_event(struct trace *trace, union perf_event *event)
{
int err;
+ printf("[debug] deliver\n");
if (!trace->sort_events)
return __trace__deliver_event(trace, event);
diff --git a/tools/perf/util/comm.c b/tools/perf/util/comm.c
index 8aa456d7c2cd..76df9886429e 100644
--- a/tools/perf/util/comm.c
+++ b/tools/perf/util/comm.c
@@ -213,6 +213,7 @@ int comm__override(struct comm *comm, const char *str, u64 timestamp, bool exec)
new = comm_strs__findnew(str);
if (!new)
return -ENOMEM;
+ printf("[OVERRIDE] old %s new %s str %s\n", old->str, new->str, str);
comm_str__put(old);
comm->comm_str = new;
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 2531b373f2cf..5a501fe304d2 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -578,6 +578,7 @@ int machine__process_comm_event(struct machine *machine, union perf_event *event
if (dump_trace)
perf_event__fprintf_comm(event, stdout);
+ printf("[debug] machine__process_comm_event\n");
if (thread == NULL ||
__thread__set_comm(thread, event->comm.comm, sample->time, exec)) {
dump_printf("problem processing PERF_RECORD_COMM, skipping event.\n");
Now, simply run this command multiple times:
$ touch /tmp/file1 && sudo /tmp/perf trace -e renameat* -- mv /tmp/file1 /tmp/file2 && rm -f /tmp/file2
And you should see two types of results:
$ touch /tmp/file1 && sudo /tmp/perf trace -e renameat* -- mv /tmp/file1 /tmp/file2 && rm -f /tmp/file2
[debug] deliver
[debug] machine__process_comm_event
[OVERRIDE] old :1221169 new mv str mv
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
0.000 ( 0.013 ms): mv/1221169 renameat2(olddfd: CWD, oldname: "/tmp/file1", newdfd: CWD, newname: "/tmp/file2", flags: NOREPLACE) = 0
[debug] deliver
$ touch /tmp/file1 && sudo /tmp/perf trace -e renameat* -- mv /tmp/file1 /tmp/file2 && rm -f /tmp/file2
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
0.000 ( 0.014 ms): :1221398/1221398 renameat2(olddfd: CWD, oldname: "/tmp/file1", newdfd: CWD, newname: "/tmp/file2", flags: NOREPLACE) = 0
[debug] deliver
[debug] deliver
[debug] machine__process_comm_event
[OVERRIDE] old :1221398 new mv str mv
[debug] deliver
[debug] deliver
[debug] deliver
Anyway, use --sort-events in BTF general tests to avoid :PID, a comm is
preferred.
[1]: https://lore.kernel.org/linux-perf-users/Z_AeswETE5xLcPT8@google.com/
Signed-off-by: Howard Chu <howardchu95@...il.com>
---
tools/perf/tests/shell/trace_btf_general.sh | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/tools/perf/tests/shell/trace_btf_general.sh b/tools/perf/tests/shell/trace_btf_general.sh
index e78e653fc8f1..a15cdb5fa309 100755
--- a/tools/perf/tests/shell/trace_btf_general.sh
+++ b/tools/perf/tests/shell/trace_btf_general.sh
@@ -27,7 +27,7 @@ check_vmlinux() {
trace_test_string() {
echo "Testing perf trace's string augmentation"
- output="$(perf trace -e renameat* --max-events=1 -- mv ${file1} ${file2} 2>&1)"
+ output="$(perf trace --sort-events -e renameat* --max-events=1 -- mv ${file1} ${file2} 2>&1)"
if ! echo "$output" | grep -q -E "^mv/[0-9]+ renameat(2)?\(.*, \"${file1}\", .*, \"${file2}\", .*\) += +[0-9]+$"
then
printf "String augmentation test failed, output:\n$output"
@@ -38,7 +38,7 @@ trace_test_string() {
trace_test_buffer() {
echo "Testing perf trace's buffer augmentation"
# echo will insert a newline (\10) at the end of the buffer
- output="$(perf trace -e write --max-events=1 -- echo "${buffer}" 2>&1)"
+ output="$(perf trace --sort-events -e write --max-events=1 -- echo "${buffer}" 2>&1)"
if ! echo "$output" | grep -q -E "^echo/[0-9]+ write\([0-9]+, ${buffer}.*, [0-9]+\) += +[0-9]+$"
then
printf "Buffer augmentation test failed, output:\n$output"
@@ -48,7 +48,7 @@ trace_test_buffer() {
trace_test_struct_btf() {
echo "Testing perf trace's struct augmentation"
- output="$(perf trace -e clock_nanosleep --force-btf --max-events=1 -- sleep 1 2>&1)"
+ output="$(perf trace --sort-events -e clock_nanosleep --force-btf --max-events=1 -- sleep 1 2>&1)"
if ! echo "$output" | grep -q -E "^sleep/[0-9]+ clock_nanosleep\(0, 0, \{1,\}, 0x[0-9a-f]+\) += +[0-9]+$"
then
printf "BTF struct augmentation test failed, output:\n$output"
--
2.45.2
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