perf tools: Improve call graph documents and help messages

The --call-graph option is complex so we should provide better guide for
users.  Also change help message to be consistent with config option
names.  Now perf top will show help like below:

  $ perf top --call-graph
    Error: option `call-graph' requires a value

   Usage: perf top [<options>]

      --call-graph <record_mode[,record_size],print_type,threshold[,print_limit],order,sort_key[,branch]>
           setup and enables call-graph (stack chain/backtrace):

		record_mode:	call graph recording mode (fp|dwarf|lbr)
		record_size:	if record_mode is 'dwarf', max size of stack recording (<bytes>)
				default: 8192 (bytes)
		print_type:	call graph printing style (graph|flat|fractal|none)
		threshold:	minimum call graph inclusion threshold (<percent>)
		print_limit:	maximum number of call graph entry (<number>)
		order:		call graph order (caller|callee)
		sort_key:	call graph sort key (function|address)
		branch:		include last branch info to call graph (branch)

		Default: fp,graph,0.5,caller,function

Requested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Chandler Carruth <chandlerc@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1445524112-5201-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 7 insertions, 4 deletions

diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 545c51cef7f7..50dd4d3d8667 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -625,8 +625,11 @@ parse_percent_limit(const struct option *opt, const char *str,
         return 0;
 }
 
-const char report_callchain_help[] = "Display callchains using " CALLCHAIN_REPORT_HELP ". "
-                                     "Default: graph,0.5,caller";
+#define CALLCHAIN_DEFAULT_OPT  "graph,0.5,caller,function"
+
+const char report_callchain_help[] = "Display call graph (stack chain/backtrace):\n\n"
+                                     CALLCHAIN_REPORT_HELP
+                                     "\n\t\t\t\tDefault: " CALLCHAIN_DEFAULT_OPT;
 
 int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
 {
@@ -636,7 +639,7 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
         bool has_br_stack = false;
         int branch_mode = -1;
         bool branch_call_mode = false;
-        char callchain_default_opt[] = "graph,0.5,caller";
+        char callchain_default_opt[] = CALLCHAIN_DEFAULT_OPT;
         const char * const report_usage[] = {
                 "perf report [<options>]",
                 NULL
@@ -703,7 +706,7 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
         OPT_BOOLEAN('x', "exclude-other", &symbol_conf.exclude_other,
                     "Only display entries with parent-match"),
         OPT_CALLBACK_DEFAULT('g', "call-graph", &report,
-                             "output_type,min_percent[,print_limit],call_order[,branch]",
+                             "print_type,threshold[,print_limit],order,sort_key[,branch]",
                              report_callchain_help, &report_parse_callchain_opt,
                              callchain_default_opt),
         OPT_BOOLEAN(0, "children", &symbol_conf.cumulate_callchain,