[PATCH v6 17/18] perf script: Display PERF_RECORD_CALLCHAIN_DEFERRED

Steven Rostedt
2025-04-25T14:56:16Z

From: Namhyung Kim <namhyung@kernel.org>

Handle the deferred callchains in the script output.

$ perf script
perf 801 [000] 18.031793: 1 cycles:P:
ffffffff91a14c36 __intel_pmu_enable_all.isra.0+0x56 ([kernel.kallsyms])
ffffffff91d373e9 perf_ctx_enable+0x39 ([kernel.kallsyms])
ffffffff91d36af7 event_function+0xd7 ([kernel.kallsyms])
ffffffff91d34222 remote_function+0x42 ([kernel.kallsyms])
ffffffff91c1ebe1 generic_exec_single+0x61 ([kernel.kallsyms])
ffffffff91c1edac smp_call_function_single+0xec ([kernel.kallsyms])
ffffffff91d37a9d event_function_call+0x10d ([kernel.kallsyms])
ffffffff91d33557 perf_event_for_each_child+0x37 ([kernel.kallsyms])
ffffffff91d47324 _perf_ioctl+0x204 ([kernel.kallsyms])
ffffffff91d47c43 perf_ioctl+0x33 ([kernel.kallsyms])
ffffffff91e2f216 __x64_sys_ioctl+0x96 ([kernel.kallsyms])
ffffffff9265f1ae do_syscall_64+0x9e ([kernel.kallsyms])
ffffffff92800130 entry_SYSCALL_64+0xb0 ([kernel.kallsyms])

perf 801 [000] 18.031814: DEFERRED CALLCHAIN
7fb5fc22034b __GI___ioctl+0x3b (/usr/lib/x86_64-linux-gnu/libc.so.6)

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
tools/perf/builtin-script.c | 89 +++++++++++++++++++++++++++++++++++++
1 file changed, 89 insertions(+)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 9b16df881af8..176b8f299afc 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -2483,6 +2483,93 @@ static int process_sample_event(const struct perf_tool *tool,
return ret;
}

+static int process_deferred_sample_event(const struct perf_tool *tool,
+ union perf_event *event,
+ struct perf_sample *sample,
+ struct evsel *evsel,
+ struct machine *machine)
+{
+ struct perf_script *scr = container_of(tool, struct perf_script, tool);
+ struct perf_event_attr *attr = &evsel->core.attr;
+ struct evsel_script *es = evsel->priv;
+ unsigned int type = output_type(attr->type);
+ struct addr_location al;
+ FILE *fp = es->fp;
+ int ret = 0;
+
+ if (output[type].fields == 0)
+ return 0;
+
+ /* Set thread to NULL to indicate addr_al and al are not initialized */
+ addr_location__init(&al);
+
+ if (perf_time__ranges_skip_sample(scr->ptime_range, scr->range_num,
+ sample->time)) {
+ goto out_put;
+ }
+
+ if (debug_mode) {
+ if (sample->time < last_timestamp) {
+ pr_err("Samples misordered, previous: %" PRIu64
+ " this: %" PRIu64 "\n", last_timestamp,
+ sample->time);
+ nr_unordered++;
+ }
+ last_timestamp = sample->time;
+ goto out_put;
+ }
+
+ if (filter_cpu(sample))
+ goto out_put;
+
+ if (machine__resolve(machine, &al, sample) < 0) {
+ pr_err("problem processing %d event, skipping it.\n",
+ event->header.type);
+ ret = -1;
+ goto out_put;
+ }
+
+ if (al.filtered)
+ goto out_put;
+
+ if (!show_event(sample, evsel, al.thread, &al, NULL))
+ goto out_put;
+
+ if (evswitch__discard(&scr->evswitch, evsel))
+ goto out_put;
+
+ perf_sample__fprintf_start(scr, sample, al.thread, evsel,
+ PERF_RECORD_CALLCHAIN_DEFERRED, fp);
+ fprintf(fp, "DEFERRED CALLCHAIN");
+
+ if (PRINT_FIELD(IP)) {
+ struct callchain_cursor *cursor = NULL;
+
+ if (symbol_conf.use_callchain && sample->callchain) {
+ cursor = get_tls_callchain_cursor();
+ if (thread__resolve_callchain(al.thread, cursor, evsel,
+ sample, NULL, NULL,
+ scripting_max_stack)) {
+ pr_info("cannot resolve deferred callchains\n");
+ cursor = NULL;
+ }
+ }
+
+ fputc(cursor ? '\n' : ' ', fp);
+ sample__fprintf_sym(sample, &al, 0, output[type].print_ip_opts,
+ cursor, symbol_conf.bt_stop_list, fp);
+ }
+
+ fprintf(fp, "\n");
+
+ if (verbose > 0)
+ fflush(fp);
+
+out_put:
+ addr_location__exit(&al);
+ return ret;
+}
+
// Used when scr->per_event_dump is not set
static struct evsel_script es_stdout;

@@ -4069,6 +4156,7 @@ int cmd_script(int argc, const char **argv)

perf_tool__init(&script.tool, !unsorted_dump);
script.tool.sample = process_sample_event;
+ script.tool.callchain_deferred = process_deferred_sample_event;
script.tool.mmap = perf_event__process_mmap;
script.tool.mmap2 = perf_event__process_mmap2;
script.tool.comm = perf_event__process_comm;
@@ -4095,6 +4183,7 @@ int cmd_script(int argc, const char **argv)
script.tool.throttle = process_throttle_event;
script.tool.unthrottle = process_throttle_event;
script.tool.ordering_requires_timestamps = true;
+ script.tool.merge_deferred_callchains = false;
session = perf_session__new(&data, &script.tool);
if (IS_ERR(session))
return PTR_ERR(session);
--
2.47.2