perf report: Support folded callchain mode on --stdio

Add new call chain option (-g) 'folded' to print callchains in a line.
The callchains are separated by semicolons, and preceded by (absolute)
percent values and a space.

For example, the following 20 lines can be printed in 3 lines with the
folded output mode:

  $ perf report -g flat --no-children | grep -v ^# | head -20
      60.48%  swapper  [kernel.vmlinux]  [k] intel_idle
              54.60%
                 intel_idle
                 cpuidle_enter_state
                 cpuidle_enter
                 call_cpuidle
                 cpu_startup_entry
                 start_secondary

              5.88%
                 intel_idle
                 cpuidle_enter_state
                 cpuidle_enter
                 call_cpuidle
                 cpu_startup_entry
                 rest_init
                 start_kernel
                 x86_64_start_reservations
                 x86_64_start_kernel

  $ perf report -g folded --no-children | grep -v ^# | head -3
      60.48%  swapper  [kernel.vmlinux]  [k] intel_idle
  54.60% intel_idle;cpuidle_enter_state;cpuidle_enter;call_cpuidle;cpu_startup_entry;start_secondary
  5.88% intel_idle;cpuidle_enter_state;cpuidle_enter;call_cpuidle;cpu_startup_entry;rest_init;start_kernel;x86_64_start_reservations;x86_64_start_kernel

This mode is supported only for --stdio now and intended to be used by
some scripts like in FlameGraphs[1].  Support for other UI might be
added later.

[1] http://www.brendangregg.com/FlameGraphs/cpuflamegraphs.html

Requested-and-Tested-by: Brendan Gregg <brendan.d.gregg@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1447047946-1691-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-report.txt

@@ -181,6 +181,7 @@ OPTIONS
 	- graph: use a graph tree, displaying absolute overhead rates. (default)
 	- fractal: like graph, but displays relative rates. Each branch of
 		 the tree is considered as a new profiled object.
+	- folded: call chains are displayed in a line, separated by semicolons
 	- none: disable call chain display.
 
 	threshold is a percentage value which specifies a minimum percent to be

tools/perf/ui/stdio/hist.c

@@ -260,6 +260,58 @@ static size_t callchain__fprintf_flat(FILE *fp, struct rb_root *tree,
 	return ret;
 }
 
+static size_t __callchain__fprintf_folded(FILE *fp, struct callchain_node *node)
+{
+	const char *sep = symbol_conf.field_sep ?: ";";
+	struct callchain_list *chain;
+	size_t ret = 0;
+	char bf[1024];
+	bool first;
+
+	if (!node)
+		return 0;
+
+	ret += __callchain__fprintf_folded(fp, node->parent);
+
+	first = (ret == 0);
+	list_for_each_entry(chain, &node->val, list) {
+		if (chain->ip >= PERF_CONTEXT_MAX)
+			continue;
+		ret += fprintf(fp, "%s%s", first ? "" : sep,
+			       callchain_list__sym_name(chain,
+						bf, sizeof(bf), false));
+		first = false;
+	}
+
+	return ret;
+}
+
+static size_t callchain__fprintf_folded(FILE *fp, struct rb_root *tree,
+					u64 total_samples)
+{
+	size_t ret = 0;
+	u32 entries_printed = 0;
+	struct callchain_node *chain;
+	struct rb_node *rb_node = rb_first(tree);
+
+	while (rb_node) {
+		double percent;
+
+		chain = rb_entry(rb_node, struct callchain_node, rb_node);
+		percent = chain->hit * 100.0 / total_samples;
+
+		ret += fprintf(fp, "%.2f%% ", percent);
+		ret += __callchain__fprintf_folded(fp, chain);
+		ret += fprintf(fp, "\n");
+		if (++entries_printed == callchain_param.print_limit)
+			break;
+
+		rb_node = rb_next(rb_node);
+	}
+
+	return ret;
+}
+
 static size_t hist_entry_callchain__fprintf(struct hist_entry *he,
 					    u64 total_samples, int left_margin,
 					    FILE *fp)
@@ -278,6 +330,9 @@ static size_t hist_entry_callchain__fprintf(struct hist_entry *he,
 	case CHAIN_FLAT:
 		return callchain__fprintf_flat(fp, &he->sorted_chain, total_samples);
 		break;
+	case CHAIN_FOLDED:
+		return callchain__fprintf_folded(fp, &he->sorted_chain, total_samples);
+		break;
 	case CHAIN_NONE:
 		break;
 	default:

tools/perf/util/callchain.c

@@ -44,6 +44,10 @@ static int parse_callchain_mode(const char *value)
 		callchain_param.mode = CHAIN_GRAPH_REL;
 		return 0;
 	}
+	if (!strncmp(value, "folded", strlen(value))) {
+		callchain_param.mode = CHAIN_FOLDED;
+		return 0;
+	}
 	return -1;
 }
 
@@ -218,6 +222,7 @@ rb_insert_callchain(struct rb_root *root, struct callchain_node *chain,
 
 		switch (mode) {
 		case CHAIN_FLAT:
+		case CHAIN_FOLDED:
 			if (rnode->hit < chain->hit)
 				p = &(*p)->rb_left;
 			else
@@ -338,6 +343,7 @@ int callchain_register_param(struct callchain_param *param)
 		param->sort = sort_chain_graph_rel;
 		break;
 	case CHAIN_FLAT:
+	case CHAIN_FOLDED:
 		param->sort = sort_chain_flat;
 		break;
 	case CHAIN_NONE:

tools/perf/util/callchain.h

@@ -24,7 +24,7 @@
 #define CALLCHAIN_RECORD_HELP  CALLCHAIN_HELP RECORD_MODE_HELP RECORD_SIZE_HELP
 
 #define CALLCHAIN_REPORT_HELP						\
-	HELP_PAD "print_type:\tcall graph printing style (graph|flat|fractal|none)\n" \
+	HELP_PAD "print_type:\tcall graph printing style (graph|flat|fractal|folded|none)\n" \
 	HELP_PAD "threshold:\tminimum call graph inclusion threshold (<percent>)\n" \
 	HELP_PAD "print_limit:\tmaximum number of call graph entry (<number>)\n" \
 	HELP_PAD "order:\t\tcall graph order (caller|callee)\n" \
@@ -43,7 +43,8 @@ enum chain_mode {
 	CHAIN_NONE,
 	CHAIN_FLAT,
 	CHAIN_GRAPH_ABS,
-	CHAIN_GRAPH_REL
+	CHAIN_GRAPH_REL,
+	CHAIN_FOLDED,
 };
 
 enum chain_order {