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 <jolsa@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1349448287-18919-5-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/ui/hist.c b/tools/perf/ui/hist.c
index 659f2a2..522b4ec 100644
--- a/tools/perf/ui/hist.c
+++ b/tools/perf/ui/hist.c
@@ -286,6 +286,35 @@
 	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 @@
 	{ .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) }
 };