perf script: Allow creating per-event dump files

Introduce a new option to dump trace output to files named by the
monitored events and update perf-script documentation accordingly.

Shown below is output of perf script command with the newly introduced
option.

         $ perf record -e cycles -e cs -ag -- sleep 1
         $ perf script --per-event-dump
         $ ls
         perf.data.cycles.dump perf.data.cs.dump

Without per-event-dump support, drawing flamegraphs for different events
would require post processing to separate events. You can monitor only
one event at a time if you want to get flamegraphs for different events.
Using this option, you can get the trace output files named by the
monitored events, and could draw flamegraphs according to the event's
name.

Based-on-a-patch-by: yuzhoujian <yuzhoujian@didichuxing.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1508921599-10832-3-git-send-email-yuzhoujian@didichuxing.com
Link: http://lkml.kernel.org/n/tip-8ngzsjdhgiovkupl3r5yy570@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 58 insertions, 1 deletions

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index b27f21638207..fb5e49b3bc44 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -1392,6 +1392,7 @@ struct perf_script {
         bool                    show_switch_events;
         bool                    show_namespace_events;
         bool                    allocated;
+        bool                    per_event_dump;
         struct cpu_map          *cpus;
         struct thread_map       *threads;
         int                     name_width;
@@ -1438,7 +1439,7 @@ static void process_event(struct perf_script *script,
         struct thread *thread = al->thread;
         struct perf_event_attr *attr = &evsel->attr;
         unsigned int type = output_type(attr->type);
-        FILE *fp = stdout;
+        FILE *fp = evsel->priv;
 
         if (output[type].fields == 0)
                 return;
@@ -1887,6 +1888,52 @@ static void sig_handler(int sig __maybe_unused)
         session_done = 1;
 }
 
+static void perf_script__fclose_per_event_dump(struct perf_script *script)
+{
+        struct perf_evlist *evlist = script->session->evlist;
+        struct perf_evsel *evsel;
+
+        evlist__for_each_entry(evlist, evsel) {
+                if (!evsel->priv)
+                        break;
+                fclose(evsel->priv);
+                evsel->priv = NULL;
+        }
+}
+
+static int perf_script__fopen_per_event_dump(struct perf_script *script)
+{
+        struct perf_evsel *evsel;
+
+        evlist__for_each_entry(script->session->evlist, evsel) {
+                char filename[PATH_MAX];
+                snprintf(filename, sizeof(filename), "%s.%s.dump",
+                         script->session->file->path, perf_evsel__name(evsel));
+                evsel->priv = fopen(filename, "w");
+                if (evsel->priv == NULL)
+                        goto out_err_fclose;
+        }
+
+        return 0;
+
+out_err_fclose:
+        perf_script__fclose_per_event_dump(script);
+        return -1;
+}
+
+static int perf_script__setup_per_event_dump(struct perf_script *script)
+{
+        struct perf_evsel *evsel;
+
+        if (script->per_event_dump)
+                return perf_script__fopen_per_event_dump(script);
+
+        evlist__for_each_entry(script->session->evlist, evsel)
+                evsel->priv = stdout;
+
+        return 0;
+}
+
 static int __cmd_script(struct perf_script *script)
 {
         int ret;
@@ -1908,8 +1955,16 @@ static int __cmd_script(struct perf_script *script)
         if (script->show_namespace_events)
                 script->tool.namespaces = process_namespaces_event;
 
+        if (perf_script__setup_per_event_dump(script)) {
+                pr_err("Couldn't create the per event dump files\n");
+                return -1;
+        }
+
         ret = perf_session__process_events(script->session);
 
+        if (script->per_event_dump)
+                perf_script__fclose_per_event_dump(script);
+
         if (debug_mode)
                 pr_err("Misordered timestamps: %" PRIu64 "\n", nr_unordered);
 
@@ -2827,6 +2882,8 @@ int cmd_script(int argc, const char **argv)
                     "Show context switch events (if recorded)"),
         OPT_BOOLEAN('\0', "show-namespace-events", &script.show_namespace_events,
                     "Show namespace events (if recorded)"),
+        OPT_BOOLEAN('\0', "per-event-dump", &script.per_event_dump,
+                    "Dump trace output to files named by the monitored events"),
         OPT_BOOLEAN('f', "force", &symbol_conf.force, "don't complain, do it"),
         OPT_INTEGER(0, "max-blocks", &max_blocks,
                     "Maximum number of code blocks to dump with brstackinsn"),