perf diff: Add weighted diff computation way to compare hist entries

Adding 'wdiff' as new computation way to compare hist entries.

If specified the 'Weighted diff' column is displayed with value 'd'
computed as:

   d = B->period * WEIGHT-A - A->period * WEIGHT-B

  - 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
  - WEIGHT-A/WEIGHT-B being user suplied weights in the the '-c' option
    behind ':' separator like '-c wdiff:1,2'.

Signed-off-by: Jiri Olsa <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Corey Ashford <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

tools/perf/Documentation/perf-diff.txt

@@ -78,7 +78,7 @@ OPTIONS
 
 -c::
 --compute::
-        Differential computation selection - delta,ratio (default is delta).
+        Differential computation selection - delta,ratio,wdiff (default is delta).
         If '+' is specified as a first character, the output is sorted based
         on the computation results.
         See COMPARISON METHODS section for more info.
@@ -110,6 +110,19 @@ with:
 
   - period being the hist entry period value
 
+wdiff
+~~~~~
+If specified the 'Weighted diff' column is displayed with value 'd' computed as:
+
+   d = B->period * WEIGHT-A - A->period * WEIGHT-B
+
+  - 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
+
+  - WEIGHT-A/WEIGHT-B being user suplied weights in the the '-c' option
+    behind ':' separator like '-c wdiff:1,2'.
 
 SEE ALSO
 --------

tools/perf/builtin-diff.c

@@ -27,24 +27,81 @@ static bool show_displacement;
 static bool show_baseline_only;
 static bool sort_compute;
 
+static s64 compute_wdiff_w1;
+static s64 compute_wdiff_w2;
+
 enum {
 	COMPUTE_DELTA,
 	COMPUTE_RATIO,
+	COMPUTE_WEIGHTED_DIFF,
 	COMPUTE_MAX,
 };
 
 const char *compute_names[COMPUTE_MAX] = {
 	[COMPUTE_DELTA] = "delta",
 	[COMPUTE_RATIO] = "ratio",
+	[COMPUTE_WEIGHTED_DIFF] = "wdiff",
 };
 
 static int compute;
 
+static int setup_compute_opt_wdiff(char *opt)
+{
+	char *w1_str = opt;
+	char *w2_str;
+
+	int ret = -EINVAL;
+
+	if (!opt)
+		goto out;
+
+	w2_str = strchr(opt, ',');
+	if (!w2_str)
+		goto out;
+
+	*w2_str++ = 0x0;
+	if (!*w2_str)
+		goto out;
+
+	compute_wdiff_w1 = strtol(w1_str, NULL, 10);
+	compute_wdiff_w2 = strtol(w2_str, NULL, 10);
+
+	if (!compute_wdiff_w1 || !compute_wdiff_w2)
+		goto out;
+
+	pr_debug("compute wdiff w1(%" PRId64 ") w2(%" PRId64 ")\n",
+		  compute_wdiff_w1, compute_wdiff_w2);
+
+	ret = 0;
+
+ out:
+	if (ret)
+		pr_err("Failed: wrong weight data, use 'wdiff:w1,w2'\n");
+
+	return ret;
+}
+
+static int setup_compute_opt(char *opt)
+{
+	if (compute == COMPUTE_WEIGHTED_DIFF)
+		return setup_compute_opt_wdiff(opt);
+
+	if (opt) {
+		pr_err("Failed: extra option specified '%s'", opt);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int setup_compute(const struct option *opt, const char *str,
 			 int unset __maybe_unused)
 {
 	int *cp = (int *) opt->value;
+	char *cstr = (char *) str;
+	char buf[50];
 	unsigned i;
+	char *option;
 
 	if (!str) {
 		*cp = COMPUTE_DELTA;
@@ -53,19 +110,37 @@ static int setup_compute(const struct option *opt, const char *str,
 
 	if (*str == '+') {
 		sort_compute = true;
-		str++;
+		cstr = (char *) ++str;
 		if (!*str)
 			return 0;
 	}
 
+	option = strchr(str, ':');
+	if (option) {
+		unsigned len = option++ - str;
+
+		/*
+		 * The str data are not writeable, so we need
+		 * to use another buffer.
+		 */
+
+		/* No option value is longer. */
+		if (len >= sizeof(buf))
+			return -EINVAL;
+
+		strncpy(buf, str, len);
+		buf[len] = 0x0;
+		cstr = buf;
+	}
+
 	for (i = 0; i < COMPUTE_MAX; i++)
-		if (!strcmp(str, compute_names[i])) {
+		if (!strcmp(cstr, compute_names[i])) {
 			*cp = i;
-			return 0;
+			return setup_compute_opt(option);
 		}
 
 	pr_err("Failed: '%s' is not computation method "
-	       "(use 'delta' or 'ratio').\n", str);
+	       "(use 'delta','ratio' or 'wdiff')\n", str);
 	return -EINVAL;
 }
 
@@ -97,6 +172,23 @@ double perf_diff__compute_ratio(struct hist_entry *he)
 	return he->diff.period_ratio;
 }
 
+s64 perf_diff__compute_wdiff(struct hist_entry *he)
+{
+	struct hist_entry *pair = he->pair;
+	u64 new_period = he->stat.period;
+	u64 old_period = pair ? pair->stat.period : 0;
+
+	he->diff.computed = true;
+
+	if (!pair)
+		he->diff.wdiff = 0;
+	else
+		he->diff.wdiff = new_period * compute_wdiff_w2 -
+				 old_period * compute_wdiff_w1;
+
+	return he->diff.wdiff;
+}
+
 static int hists__add_entry(struct hists *self,
 			    struct addr_location *al, u64 period)
 {
@@ -275,6 +367,9 @@ static void hists__precompute(struct hists *hists)
 		case COMPUTE_RATIO:
 			perf_diff__compute_ratio(he);
 			break;
+		case COMPUTE_WEIGHTED_DIFF:
+			perf_diff__compute_wdiff(he);
+			break;
 		default:
 			BUG_ON(1);
 		}
@@ -310,6 +405,13 @@ hist_entry__cmp_compute(struct hist_entry *left, struct hist_entry *right,
 
 		return cmp_doubles(l, r);
 	}
+	case COMPUTE_WEIGHTED_DIFF:
+	{
+		s64 l = left->diff.wdiff;
+		s64 r = right->diff.wdiff;
+
+		return r - l;
+	}
 	default:
 		BUG_ON(1);
 	}
@@ -434,7 +536,8 @@ 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_CALLBACK('c', "compute", &compute, "delta,ratio (default delta)",
+	OPT_CALLBACK('c', "compute", &compute,
+		     "delta,ratio,wdiff:w1,w2 (default delta)",
 		     "Entries differential computation selection",
 		     setup_compute),
 	OPT_BOOLEAN('D', "dump-raw-trace", &dump_trace,
@@ -475,6 +578,9 @@ static void ui_init(void)
 	case COMPUTE_RATIO:
 		perf_hpp__column_enable(PERF_HPP__RATIO, true);
 		break;
+	case COMPUTE_WEIGHTED_DIFF:
+		perf_hpp__column_enable(PERF_HPP__WEIGHTED_DIFF, true);
+		break;
 	default:
 		BUG_ON(1);
 	};

tools/perf/ui/hist.c

@@ -286,6 +286,35 @@ static int hpp__entry_ratio(struct perf_hpp *hpp, struct hist_entry *he)
 	return scnprintf(hpp->buf, hpp->size, fmt, buf);
 }
 
+static int hpp__header_wdiff(struct perf_hpp *hpp)
+{
+	const char *fmt = symbol_conf.field_sep ? "%s" : "%14s";
+
+	return scnprintf(hpp->buf, hpp->size, fmt, "Weighted diff");
+}
+
+static int hpp__width_wdiff(struct perf_hpp *hpp __maybe_unused)
+{
+	return 14;
+}
+
+static int hpp__entry_wdiff(struct perf_hpp *hpp, struct hist_entry *he)
+{
+	const char *fmt = symbol_conf.field_sep ? "%s" : "%14s";
+	char buf[32] = " ";
+	s64 wdiff;
+
+	if (he->diff.computed)
+		wdiff = he->diff.wdiff;
+	else
+		wdiff = perf_diff__compute_wdiff(he);
+
+	if (wdiff != 0)
+		scnprintf(buf, sizeof(buf), "%14ld", wdiff);
+
+	return scnprintf(hpp->buf, hpp->size, fmt, buf);
+}
+
 static int hpp__header_displ(struct perf_hpp *hpp)
 {
 	return scnprintf(hpp->buf, hpp->size, "Displ.");
@@ -332,6 +361,7 @@ struct perf_hpp_fmt perf_hpp__format[] = {
 	{ .cond = false, HPP__PRINT_FNS(period) },
 	{ .cond = false, HPP__PRINT_FNS(delta) },
 	{ .cond = false, HPP__PRINT_FNS(ratio) },
+	{ .cond = false, HPP__PRINT_FNS(wdiff) },
 	{ .cond = false, HPP__PRINT_FNS(displ) }
 };
 

tools/perf/util/hist.h

@@ -142,6 +142,7 @@ enum {
 	PERF_HPP__PERIOD,
 	PERF_HPP__DELTA,
 	PERF_HPP__RATIO,
+	PERF_HPP__WEIGHTED_DIFF,
 	PERF_HPP__DISPL,
 
 	PERF_HPP__MAX_INDEX
@@ -207,4 +208,5 @@ unsigned int hists__sort_list_width(struct hists *self);
 
 double perf_diff__compute_delta(struct hist_entry *he);
 double perf_diff__compute_ratio(struct hist_entry *he);
+s64 perf_diff__compute_wdiff(struct hist_entry *he);
 #endif	/* __PERF_HIST_H */

tools/perf/util/sort.h

@@ -63,6 +63,9 @@ struct hist_entry_diff {
 
 	/* PERF_HPP__RATIO */
 	double	period_ratio;
+
+	/* HISTC_WEIGHTED_DIFF */
+	s64	wdiff;
 };
 
 /**