perf hist: Only allocate callchain_node if processing callchains

The struct callchain_node size is 120 bytes, that are never used when
there are no callchains or '-g none' is specified, so conditionally
allocate it, reducing sizeof(struct hist_entry) from 210 bytes to only
96, greatly speeding the non-callchain processing.

LKML-Reference: <new-submission>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

3 files changed, 6 insertions, 5 deletions

diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 381918515a5c..1fb13e5fd1f9 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -110,8 +110,8 @@ static int perf_session__add_hist_entry(struct perf_session *self,
 
         if (symbol_conf.use_callchain) {
                 if (!hit)
-                        callchain_init(&he->callchain);
-                err = append_chain(&he->callchain, data->callchain, syms);
+                        callchain_init(he->callchain);
+                err = append_chain(he->callchain, data->callchain, syms);
                 free(syms);
 
                 if (err)
diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index f0794913d575..18cf8b321608 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -50,7 +50,8 @@ struct hist_entry *__perf_session__add_hist_entry(struct rb_root *hists,
                         p = &(*p)->rb_right;
         }
 
-        he = malloc(sizeof(*he));
+        he = malloc(sizeof(*he) + (symbol_conf.use_callchain ?
+                                    sizeof(struct callchain_node) : 0));
         if (!he)
                 return NULL;
         *he = entry;
@@ -168,7 +169,7 @@ static void perf_session__insert_output_hist_entry(struct rb_root *root,
         struct hist_entry *iter;
 
         if (symbol_conf.use_callchain)
-                callchain_param.sort(&he->sorted_chain, &he->callchain,
+                callchain_param.sort(&he->sorted_chain, he->callchain,
                                       min_callchain_hits, &callchain_param);
 
         while (*p != NULL) {
diff --git a/tools/perf/util/sort.h b/tools/perf/util/sort.h
index 439ec5fa0f5f..5bf2b744e7b2 100644
--- a/tools/perf/util/sort.h
+++ b/tools/perf/util/sort.h
@@ -49,12 +49,12 @@ struct hist_entry {
         u64                     ip;
         char                    level;
         struct symbol     *parent;
-        struct callchain_node   callchain;
         union {
                 unsigned long     position;
                 struct hist_entry *pair;
                 struct rb_root    sorted_chain;
         };
+        struct callchain_node   callchain[0];
 };
 
 enum sort_type {