[RFC/PATCH v2 1/4] perf report: Support folded callchain mode on --stdio

[Namhyung Kim <namhyung@kernel.org>]

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

For example, 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
  intel_idle;cpuidle_enter_state;cpuidle_enter;call_cpuidle;cpu_startup_entry;start_secondary 54.60%
  intel_idle;cpuidle_enter_state;cpuidle_enter;call_cpuidle;cpu_startup_entry;rest_init;start_kernel;x86_64_start_reservations;x86_64_start_kernel  5.88%

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-by: Brendan Gregg <brendan.d.gregg@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/ui/stdio/hist.c  | 53 +++++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/callchain.c |  6 +++++
 tools/perf/util/callchain.h |  3 ++-
 3 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/tools/perf/ui/stdio/hist.c b/tools/perf/ui/stdio/hist.c
index dfcbc90146ef..2c7436241912 100644
--- a/tools/perf/ui/stdio/hist.c
+++ b/tools/perf/ui/stdio/hist.c
@@ -260,6 +260,56 @@ 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)
+{
+	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 ? "" : ";",
+			       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 += __callchain__fprintf_folded(fp, chain);
+		ret += fprintf(fp, " %6.2f%%\n", percent);
+		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 +328,9 @@ 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:
diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 735ad48e1858..08cb220ba5ea 100644
--- a/tools/perf/util/callchain.c
+++ b/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:
diff --git a/tools/perf/util/callchain.h b/tools/perf/util/callchain.h
index fce8161e54db..2f305384531f 100644
--- a/tools/perf/util/callchain.h
+++ b/tools/perf/util/callchain.h
@@ -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 {
-- 
2.6.2