perf callchain: Convert children list to rbtree
Current collapse stage has a scalability problem which can be reproduced
easily with a parallel kernel build.
This is because it needs to traverse every children of callchains
linearly during the collapse/merge stage.
Converting it to a rbtree reduced the overhead significantly.
On my 400MB perf.data file which recorded with make -j32 kernel build:
$ time perf --no-pager report --stdio > /dev/null
before:
real 6m22.073s
user 6m18.683s
sys 0m0.706s
after:
real 0m20.780s
user 0m19.962s
sys 0m0.689s
During the perf report the overhead on append_chain_children went down
from 96.69% to 18.16%:
- 18.16% perf perf [.] append_chain_children
- append_chain_children
- 77.48% append_chain_children
+ 69.79% merge_chain_branch
- 22.96% append_chain_children
+ 67.44% merge_chain_branch
+ 30.15% append_chain_children
+ 2.41% callchain_append
+ 7.25% callchain_append
+ 12.26% callchain_append
+ 10.22% merge_chain_branch
+ 11.58% perf perf [.] dso__find_symbol
+ 8.02% perf perf [.] sort__comm_cmp
+ 5.48% perf libc-2.17.so [.] malloc_consolidate
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1381468543-25334-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/callchain.h b/tools/perf/util/callchain.h
index 2b585bc..7bb3602 100644
--- a/tools/perf/util/callchain.h
+++ b/tools/perf/util/callchain.h
@@ -21,11 +21,11 @@
struct callchain_node {
struct callchain_node *parent;
- struct list_head siblings;
- struct list_head children;
struct list_head val;
- struct rb_node rb_node; /* to sort nodes in an rbtree */
- struct rb_root rb_root; /* sorted tree of children */
+ struct rb_node rb_node_in; /* to insert nodes in an rbtree */
+ struct rb_node rb_node; /* to sort nodes in an output tree */
+ struct rb_root rb_root_in; /* input tree of children */
+ struct rb_root rb_root; /* sorted output tree of children */
unsigned int val_nr;
u64 hit;
u64 children_hit;
@@ -86,13 +86,12 @@
static inline void callchain_init(struct callchain_root *root)
{
- INIT_LIST_HEAD(&root->node.siblings);
- INIT_LIST_HEAD(&root->node.children);
INIT_LIST_HEAD(&root->node.val);
root->node.parent = NULL;
root->node.hit = 0;
root->node.children_hit = 0;
+ root->node.rb_root_in = RB_ROOT;
root->max_depth = 0;
}
