perf diff: Add option to sort entries based on diff computation

Adding support to sort hist entries based on the outcome of selected
computation. It's now possible to specify '+' as a first character of
'-c' option value to make such sort.

Example:

  $ perf diff -c ratio -b
  # Event 'cache-misses'
  #
  #   Baseline           Ratio      Shared Object                            Symbol
  #   ........  ..............  .................  ................................
  #
        19.64%            0.69  [kernel.kallsyms]  [k] clear_page
         0.30%            0.17  [kernel.kallsyms]  [k] mm_alloc
         0.04%            0.20  [kernel.kallsyms]  [k] kmem_cache_alloc

  $ perf diff -c +ratio -b
  # Event 'cache-misses'
  #
  #   Baseline           Ratio      Shared Object                            Symbol
  #   ........  ..............  .................  ................................
  #
        19.64%            0.69  [kernel.kallsyms]  [k] clear_page
         0.04%            0.20  [kernel.kallsyms]  [k] kmem_cache_alloc
         0.30%            0.17  [kernel.kallsyms]  [k] mm_alloc

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/1349448287-18919-4-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index 7e4d4c2..a7ea28a 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -205,4 +205,6 @@
 
 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);
 #endif	/* __PERF_HIST_H */
diff --git a/tools/perf/util/sort.h b/tools/perf/util/sort.h
index 5786f32..337aeef 100644
--- a/tools/perf/util/sort.h
+++ b/tools/perf/util/sort.h
@@ -52,6 +52,19 @@
 	u32			nr_events;
 };
 
+struct hist_entry_diff {
+	bool	computed;
+
+	/* PERF_HPP__DISPL */
+	int	displacement;
+
+	/* PERF_HPP__DELTA */
+	double	period_ratio_delta;
+
+	/* PERF_HPP__RATIO */
+	double	period_ratio;
+};
+
 /**
  * struct hist_entry - histogram entry
  *
@@ -67,6 +80,8 @@
 	u64			ip;
 	s32			cpu;
 
+	struct hist_entry_diff	diff;
+
 	/* XXX These two should move to some tree widget lib */
 	u16			row_offset;
 	u16			nr_rows;