[PATCH 2/2] perf record: Add --synth option

From: Namhyung Kim
Date: Thu Jul 22 2021 - 22:40:53 EST


Add an option to control synthesize behavior.

--synth <no|all|task|mmap|cgroup>
Fine-tune event synthesis: default=all

This can be useful when we know it doesn't need some synthesis like
in a specific usecase and/or when using pipe:

$ perf record -a --all-cgroups --synth cgroup -o- sleep 1 | \
> perf report -i- -s cgroup

Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
tools/perf/Documentation/perf-record.txt | 4 ++
tools/perf/builtin-record.c | 48 +++++++++++++++++++-----
tools/perf/util/record.h | 1 +
tools/perf/util/synthetic-events.c | 28 ++++++++++++++
tools/perf/util/synthetic-events.h | 12 ++++++
5 files changed, 84 insertions(+), 9 deletions(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index d71bac847936..421a7b93c4b5 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -596,6 +596,10 @@ options.
'perf record --dry-run -e' can act as a BPF script compiler if llvm.dump-obj
in config file is set to true.

+--synth=TYPE::
+Collect and synthesize given type of events. Available types are:
+task, mmap, cgroup, all, no
+
--tail-synthesize::
Instead of collecting non-sample events (for example, fork, comm, mmap) at
the beginning of record, collect them during finalizing an output file.
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 535da4dfd8d3..caaada3594ce 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1254,6 +1254,7 @@ static int record__synthesize_workload(struct record *rec, bool tail)
{
int err;
struct perf_thread_map *thread_map;
+ bool needs_mmap = rec->opts.synth & PERF_SYNTH_MMAP;

if (rec->opts.tail_synthesize != tail)
return 0;
@@ -1265,7 +1266,7 @@ static int record__synthesize_workload(struct record *rec, bool tail)
err = perf_event__synthesize_thread_map(&rec->tool, thread_map,
process_synthesized_event,
&rec->session->machines.host,
- true,
+ needs_mmap,
rec->opts.sample_address);
perf_thread_map__put(thread_map);
return err;
@@ -1500,20 +1501,26 @@ static int record__synthesize(struct record *rec, bool tail)
if (err < 0)
pr_warning("Couldn't synthesize bpf events.\n");

- err = perf_event__synthesize_cgroups(tool, process_synthesized_event,
- machine);
- if (err < 0)
- pr_warning("Couldn't synthesize cgroup events.\n");
+ if (rec->opts.synth & PERF_SYNTH_CGROUP) {
+ err = perf_event__synthesize_cgroups(tool, process_synthesized_event,
+ machine);
+ if (err < 0)
+ pr_warning("Couldn't synthesize cgroup events.\n");
+ }

if (rec->opts.nr_threads_synthesize > 1) {
perf_set_multithreaded();
f = process_locked_synthesized_event;
}

- err = __machine__synthesize_threads(machine, tool, &opts->target,
- rec->evlist->core.threads,
- f, true, opts->sample_address,
- rec->opts.nr_threads_synthesize);
+ if (rec->opts.synth & PERF_SYNTH_TASK) {
+ bool needs_mmap = rec->opts.synth & PERF_SYNTH_MMAP;
+
+ err = __machine__synthesize_threads(machine, tool, &opts->target,
+ rec->evlist->core.threads,
+ f, needs_mmap, opts->sample_address,
+ rec->opts.nr_threads_synthesize);
+ }

if (rec->opts.nr_threads_synthesize > 1)
perf_set_singlethreaded();
@@ -2422,6 +2429,26 @@ static int process_timestamp_boundary(struct perf_tool *tool,
return 0;
}

+static int parse_record_synth_option(const struct option *opt,
+ const char *str,
+ int unset __maybe_unused)
+{
+ struct record_opts *opts = opt->value;
+ char *p = strdup(str);
+
+ if (p == NULL)
+ return -1;
+
+ opts->synth = parse_synth_opt(p);
+ free(p);
+
+ if (opts->synth < 0) {
+ pr_err("Invalid synth option: %s\n", str);
+ return -1;
+ }
+ return 0;
+}
+
/*
* XXX Ideally would be local to cmd_record() and passed to a record__new
* because we need to have access to it in record__exit, that is called
@@ -2447,6 +2474,7 @@ static struct record record = {
.nr_threads_synthesize = 1,
.ctl_fd = -1,
.ctl_fd_ack = -1,
+ .synth = PERF_SYNTH_ALL,
},
.tool = {
.sample = process_sample_event,
@@ -2662,6 +2690,8 @@ static struct option __record_options[] = {
"\t\t\t Optionally send control command completion ('ack\\n') to ack-fd descriptor.\n"
"\t\t\t Alternatively, ctl-fifo / ack-fifo will be opened and used as ctl-fd / ack-fd.",
parse_control_option),
+ OPT_CALLBACK(0, "synth", &record.opts, "no|all|task|mmap|cgroup",
+ "Fine-tune event synthesis: default=all", parse_record_synth_option),
OPT_END()
};

diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
index 68f471d9a88b..ef6c2715fdd9 100644
--- a/tools/perf/util/record.h
+++ b/tools/perf/util/record.h
@@ -77,6 +77,7 @@ struct record_opts {
int ctl_fd;
int ctl_fd_ack;
bool ctl_fd_close;
+ int synth;
};

extern const char * const *record_usage;
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 566e0859fcfb..9485d0532b9c 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -2186,3 +2186,31 @@ int perf_event__synthesize_features(struct perf_tool *tool, struct perf_session
free(ff.buf);
return ret;
}
+
+int parse_synth_opt(char *synth)
+{
+ char *p, *q;
+ int ret = 0;
+
+ if (synth == NULL)
+ return -1;
+
+ for (q = synth; (p = strsep(&q, ",")); p = q) {
+ if (!strcasecmp(p, "no") || !strcasecmp(p, "none"))
+ return 0;
+
+ if (!strcasecmp(p, "all"))
+ return PERF_SYNTH_ALL;
+
+ if (!strcasecmp(p, "task"))
+ ret |= PERF_SYNTH_TASK;
+ else if (!strcasecmp(p, "mmap"))
+ ret |= PERF_SYNTH_TASK | PERF_SYNTH_MMAP;
+ else if (!strcasecmp(p, "cgroup"))
+ ret |= PERF_SYNTH_CGROUP;
+ else
+ return -1;
+ }
+
+ return ret;
+}
diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
index 61bbdb3b64df..913803506345 100644
--- a/tools/perf/util/synthetic-events.h
+++ b/tools/perf/util/synthetic-events.h
@@ -26,6 +26,18 @@ struct target;

union perf_event;

+enum perf_record_synth {
+ PERF_SYNTH_TASK = 1 << 0,
+ PERF_SYNTH_MMAP = 1 << 1,
+ PERF_SYNTH_CGROUP = 1 << 2,
+
+ /* last element */
+ PERF_SYNTH_MAX = 1 << 3,
+};
+#define PERF_SYNTH_ALL (PERF_SYNTH_MAX - 1)
+
+int parse_synth_opt(char *str);
+
typedef int (*perf_event__handler_t)(struct perf_tool *tool, union perf_event *event,
struct perf_sample *sample, struct machine *machine);

--
2.32.0.432.gabb21c7263-goog