[PATCH 07/12] perf diff: Add ratio computation way to compare hist entries

[Jiri Olsa <jolsa@redhat.com>]

Adding -c option to select computation method with the current
'Delta' computation as default. Current posible values are of
this option are: 'delta' and 'ratio'.

Adding 'ratio' as new computation way to compare hist entries.
If specified the 'Ratio' column is displayed with value 'r'
computed as:

  r = A->period / B->period

with:
  - A/B being matching hist entry from first/second file specified
    (or perf.data/perf.data.old) respectively.
  - period being the hist entry period value

Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
 tools/perf/Documentation/perf-diff.txt | 33 ++++++++++++++++++++++
 tools/perf/builtin-diff.c              | 51 +++++++++++++++++++++++++++++++++-
 tools/perf/ui/stdio/hist.c             | 13 +++++++++
 tools/perf/util/hist.h                 |  1 +
 4 files changed, 97 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Documentation/perf-diff.txt b/tools/perf/Documentation/perf-diff.txt
index 6ce9585..8fff061 100644
--- a/tools/perf/Documentation/perf-diff.txt
+++ b/tools/perf/Documentation/perf-diff.txt
@@ -76,6 +76,39 @@ OPTIONS
 --baseline-only::
         Show only items with match in baseline.
 
+-c::
+--compute::
+        Differential computation selection - delta,ratio (default is delta).
+        See COMPARISON METHODS section for more info.
+
+COMPARISON METHODS
+------------------
+delta
+~~~~~
+If specified the 'Delta' column is displayed with value 'd' computed as:
+
+  d = A->period_percent - B->period_percent
+
+with:
+  - A/B being matching hist entry from first/second file specified
+    (or perf.data/perf.data.old) respectively.
+
+  - period_percent being the % of the hist entry period value within
+    single data file
+
+ratio
+~~~~~
+If specified the 'Ratio' column is displayed with value 'r' computed as:
+
+  r = A->period / B->period
+
+with:
+  - A/B being matching hist entry from first/second file specified
+    (or perf.data/perf.data.old) respectively.
+
+  - period being the hist entry period value
+
+
 SEE ALSO
 --------
 linkperf:perf-record[1]
diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index 46f4a10..cde08d4 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -27,6 +27,39 @@ static bool  force;
 static bool show_displacement;
 static bool show_baseline_only;
 
+enum {
+	COMPUTE_DELTA,
+	COMPUTE_RATIO,
+	COMPUTE_MAX,
+};
+
+const char *compute_names[COMPUTE_MAX] = {
+	[COMPUTE_DELTA] = "delta",
+	[COMPUTE_RATIO] = "ratio",
+};
+
+static const char *compute_str;
+static int compute;
+
+static int setup_compute(void)
+{
+	unsigned i;
+
+	if (!compute_str) {
+		compute = COMPUTE_DELTA;
+		return 0;
+	}
+
+	for (i = 0; i < COMPUTE_MAX; i++)
+		if (!strcmp(compute_str, compute_names[i])) {
+			compute = i;
+			return 0;
+		}
+
+	pr_err("Failed to find valid compute string\n");
+	return -EINVAL;
+}
+
 static int hists__add_entry(struct hists *self,
 			    struct addr_location *al, u64 period)
 {
@@ -263,6 +296,8 @@ static const struct option options[] = {
 		    "Show position displacement relative to baseline"),
 	OPT_BOOLEAN('b', "baseline-only", &show_baseline_only,
 		    "Show only items with match in baseline"),
+	OPT_STRING('c', "compute", &compute_str, "delta,ratio (default delta)",
+		   "Entries differential computation selection"),
 	OPT_BOOLEAN('D', "dump-raw-trace", &dump_trace,
 		    "dump raw trace in ASCII"),
 	OPT_BOOLEAN('f', "force", &force, "don't complain, do it"),
@@ -288,7 +323,18 @@ static void setup_ui_stdio(void)
 {
 	hists_stdio_column__register_idx(HISTC_BASELINE);
 	hists_stdio_column__register_global();
-	hists_stdio_column__register_idx(HISTC_DELTA);
+
+	switch (compute) {
+	case COMPUTE_DELTA:
+		hists_stdio_column__register_idx(HISTC_DELTA);
+		break;
+	case COMPUTE_RATIO:
+		hists_stdio_column__register_idx(HISTC_RATIO);
+		break;
+	default:
+		BUG_ON(1);
+	};
+
 	if (show_displacement)
 		hists_stdio_column__register_idx(HISTC_DISPLACEMENT);
 }
@@ -315,6 +361,9 @@ int cmd_diff(int argc, const char **argv, const char *prefix __used)
 	if (symbol__init() < 0)
 		return -1;
 
+	if (setup_compute())
+		usage_with_options(diff_usage, options);
+
 	setup_sorting(diff_usage, options);
 	setup_ui_stdio();
 	setup_pager();
diff --git a/tools/perf/ui/stdio/hist.c b/tools/perf/ui/stdio/hist.c
index 48fb0b3..02ba1c7 100644
--- a/tools/perf/ui/stdio/hist.c
+++ b/tools/perf/ui/stdio/hist.c
@@ -31,6 +31,18 @@ hists_stdio_column__delta_snprintf(struct hist_entry *he, char *bf,
 }
 
 static int
+hists_stdio_column__ratio_snprintf(struct hist_entry *he, char *bf,
+				   size_t size, unsigned int width __used)
+{
+	struct hist_entry *pair = he->pair;
+	double new_period = he->period;
+	double old_period = pair ? pair->period : 0;
+	double ratio = pair ? new_period / old_period : 0;
+
+	return percent_color_snprintf(bf, size, "%14.3F", ratio);
+}
+
+static int
 hists_stdio_column__baseline_snprintf(struct hist_entry *he, char *bf,
 				      size_t size, unsigned int width __used)
 {
@@ -124,6 +136,7 @@ DEF_COLUMN(cpu_guest_us, HISTC_CPU_UTILIZATION_GUEST_US, 8, "guest us")
 DEF_COLUMN(nr_samples, HISTC_NR_SAMPLES, 12, "Samples")
 DEF_COLUMN(total_period, HISTC_TOTAL_PERIOD, 12, "Period")
 DEF_COLUMN(delta, HISTC_DELTA, 8, "Delta")
+DEF_COLUMN(ratio, HISTC_RATIO, 14, "Ratio")
 DEF_COLUMN(displacement, HISTC_DISPLACEMENT, 5, "Displ")
 };
 
diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index 36ff4c5..b24341d 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -46,6 +46,7 @@ enum hist_column {
 	HISTC_NR_SAMPLES,
 	HISTC_TOTAL_PERIOD,
 	HISTC_DELTA,
+	HISTC_RATIO,
 	HISTC_DISPLACEMENT,
 
 	/* sorted (hist_entry__sort_list) */
-- 
1.7.11.4