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Commit e369517c authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
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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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarNamhyung 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent f11cfc6f

tools/perf/util/callchain.c

+111 −36
Original line number Diff line number Diff line
@@ -21,12 +21,6 @@ 


__thread struct callchain_cursor callchain_cursor;



#define chain_for_each_child(child, parent)	\

	list_for_each_entry(child, &parent->children, siblings)



#define chain_for_each_child_safe(child, next, parent)	\

	list_for_each_entry_safe(child, next, &parent->children, siblings)



static void

rb_insert_callchain(struct rb_root *root, struct callchain_node *chain,

		    enum chain_mode mode)
@@ -71,10 +65,16 @@ static void 
__sort_chain_flat(struct rb_root *rb_root, struct callchain_node *node,

		  u64 min_hit)

{

	struct rb_node *n;

	struct callchain_node *child;



	chain_for_each_child(child, node)

	n = rb_first(&node->rb_root_in);

	while (n) {

		child = rb_entry(n, struct callchain_node, rb_node_in);

		n = rb_next(n);



		__sort_chain_flat(rb_root, child, min_hit);

	}



	if (node->hit && node->hit >= min_hit)

		rb_insert_callchain(rb_root, node, CHAIN_FLAT);
@@ -94,11 +94,16 @@ sort_chain_flat(struct rb_root *rb_root, struct callchain_root *root, 
static void __sort_chain_graph_abs(struct callchain_node *node,

				   u64 min_hit)

{

	struct rb_node *n;

	struct callchain_node *child;



	node->rb_root = RB_ROOT;

	n = rb_first(&node->rb_root_in);



	while (n) {

		child = rb_entry(n, struct callchain_node, rb_node_in);

		n = rb_next(n);



	chain_for_each_child(child, node) {

		__sort_chain_graph_abs(child, min_hit);

		if (callchain_cumul_hits(child) >= min_hit)

			rb_insert_callchain(&node->rb_root, child,
@@ -117,13 +122,18 @@ sort_chain_graph_abs(struct rb_root *rb_root, struct callchain_root *chain_root, 
static void __sort_chain_graph_rel(struct callchain_node *node,

				   double min_percent)

{

	struct rb_node *n;

	struct callchain_node *child;

	u64 min_hit;



	node->rb_root = RB_ROOT;

	min_hit = ceil(node->children_hit * min_percent);



	chain_for_each_child(child, node) {

	n = rb_first(&node->rb_root_in);

	while (n) {

		child = rb_entry(n, struct callchain_node, rb_node_in);

		n = rb_next(n);



		__sort_chain_graph_rel(child, min_percent);

		if (callchain_cumul_hits(child) >= min_hit)

			rb_insert_callchain(&node->rb_root, child,
@@ -173,19 +183,26 @@ create_child(struct callchain_node *parent, bool inherit_children) 
		return NULL;

	}

	new->parent = parent;

	INIT_LIST_HEAD(&new->children);

	INIT_LIST_HEAD(&new->val);



	if (inherit_children) {

		struct callchain_node *next;

		struct rb_node *n;

		struct callchain_node *child;



		new->rb_root_in = parent->rb_root_in;

		parent->rb_root_in = RB_ROOT;



		list_splice(&parent->children, &new->children);

		INIT_LIST_HEAD(&parent->children);

		n = rb_first(&new->rb_root_in);

		while (n) {

			child = rb_entry(n, struct callchain_node, rb_node_in);

			child->parent = new;

			n = rb_next(n);

		}



		chain_for_each_child(next, new)

			next->parent = new;

		/* make it the first child */

		rb_link_node(&new->rb_node_in, NULL, &parent->rb_root_in.rb_node);

		rb_insert_color(&new->rb_node_in, &parent->rb_root_in);

	}

	list_add_tail(&new->siblings, &parent->children);



	return new;

}
@@ -223,7 +240,7 @@ fill_node(struct callchain_node *node, struct callchain_cursor *cursor) 
	}

}



static void

static struct callchain_node *

add_child(struct callchain_node *parent,

	  struct callchain_cursor *cursor,

	  u64 period)
@@ -235,6 +252,19 @@ add_child(struct callchain_node *parent, 


	new->children_hit = 0;

	new->hit = period;

	return new;

}



static s64 match_chain(struct callchain_cursor_node *node,

		      struct callchain_list *cnode)

{

	struct symbol *sym = node->sym;



	if (cnode->ms.sym && sym &&

	    callchain_param.key == CCKEY_FUNCTION)

		return cnode->ms.sym->start - sym->start;

	else

		return cnode->ip - node->ip;

}



/*
@@ -272,9 +302,33 @@ split_add_child(struct callchain_node *parent, 


	/* create a new child for the new branch if any */

	if (idx_total < cursor->nr) {

		struct callchain_node *first;

		struct callchain_list *cnode;

		struct callchain_cursor_node *node;

		struct rb_node *p, **pp;



		parent->hit = 0;

		add_child(parent, cursor, period);

		parent->children_hit += period;



		node = callchain_cursor_current(cursor);

		new = add_child(parent, cursor, period);



		/*

		 * This is second child since we moved parent's children

		 * to new (first) child above.

		 */

		p = parent->rb_root_in.rb_node;

		first = rb_entry(p, struct callchain_node, rb_node_in);

		cnode = list_first_entry(&first->val, struct callchain_list,

					 list);



		if (match_chain(node, cnode) < 0)

			pp = &p->rb_left;

		else

			pp = &p->rb_right;



		rb_link_node(&new->rb_node_in, p, pp);

		rb_insert_color(&new->rb_node_in, &parent->rb_root_in);

	} else {

		parent->hit = period;

	}
@@ -291,16 +345,40 @@ append_chain_children(struct callchain_node *root, 
		      u64 period)

{

	struct callchain_node *rnode;

	struct callchain_cursor_node *node;

	struct rb_node **p = &root->rb_root_in.rb_node;

	struct rb_node *parent = NULL;



	node = callchain_cursor_current(cursor);

	if (!node)

		return;



	/* lookup in childrens */

	chain_for_each_child(rnode, root) {

		unsigned int ret = append_chain(rnode, cursor, period);

	while (*p) {

		s64 ret;

		struct callchain_list *cnode;



		if (!ret)

		parent = *p;

		rnode = rb_entry(parent, struct callchain_node, rb_node_in);

		cnode = list_first_entry(&rnode->val, struct callchain_list,

					 list);



		/* just check first entry */

		ret = match_chain(node, cnode);

		if (ret == 0) {

			append_chain(rnode, cursor, period);

			goto inc_children_hit;

		}



		if (ret < 0)

			p = &parent->rb_left;

		else

			p = &parent->rb_right;

	}

	/* nothing in children, add to the current node */

	add_child(root, cursor, period);

	rnode = add_child(root, cursor, period);

	rb_link_node(&rnode->rb_node_in, parent, p);

	rb_insert_color(&rnode->rb_node_in, &root->rb_root_in);



inc_children_hit:

	root->children_hit += period;
@@ -325,28 +403,20 @@ append_chain(struct callchain_node *root, 
	 */

	list_for_each_entry(cnode, &root->val, list) {

		struct callchain_cursor_node *node;

		struct symbol *sym;



		node = callchain_cursor_current(cursor);

		if (!node)

			break;



		sym = node->sym;



		if (cnode->ms.sym && sym &&

		    callchain_param.key == CCKEY_FUNCTION) {

			if (cnode->ms.sym->start != sym->start)

				break;

		} else if (cnode->ip != node->ip)

		if (match_chain(node, cnode) != 0)

			break;



		if (!found)

		found = true;



		callchain_cursor_advance(cursor);

	}



	/* matches not, relay on the parent */

	/* matches not, relay no the parent */

	if (!found) {

		cursor->curr = curr_snap;

		cursor->pos = start;
@@ -395,8 +465,9 @@ merge_chain_branch(struct callchain_cursor *cursor, 
		   struct callchain_node *dst, struct callchain_node *src)

{

	struct callchain_cursor_node **old_last = cursor->last;

	struct callchain_node *child, *next_child;

	struct callchain_node *child;

	struct callchain_list *list, *next_list;

	struct rb_node *n;

	int old_pos = cursor->nr;

	int err = 0;
@@ -412,12 +483,16 @@ merge_chain_branch(struct callchain_cursor *cursor, 
		append_chain_children(dst, cursor, src->hit);

	}



	chain_for_each_child_safe(child, next_child, src) {

	n = rb_first(&src->rb_root_in);

	while (n) {

		child = container_of(n, struct callchain_node, rb_node_in);

		n = rb_next(n);

		rb_erase(&child->rb_node_in, &src->rb_root_in);



		err = merge_chain_branch(cursor, dst, child);

		if (err)

			break;



		list_del(&child->siblings);

		free(child);

	}

tools/perf/util/callchain.h

+5 −6
Original line number Diff line number Diff line
@@ -21,11 +21,11 @@ enum chain_order { 


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 @@ extern __thread struct callchain_cursor callchain_cursor; 


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;

}