perf_counter tools: Prepare a small callchain framework

We plan to display the callchains depending on some user-configurable
parameters.

To gather the callchains stats from the recorded stream in a fast way,
this patch introduces an ad hoc radix tree adapted for callchains and also
a rbtree to sort these callchains once we have gathered every events
from the stream.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1246026481-8314-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 174 insertions, 0 deletions

diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
new file mode 100644
index 000000000000..ad3c28578961
--- /dev/null
+++ b/tools/perf/util/callchain.c
@@ -0,0 +1,174 @@
+/*
+ * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com>
+ *
+ * Handle the callchains from the stream in an ad-hoc radix tree and then
+ * sort them in an rbtree.
+ *
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <errno.h>
+
+#include "callchain.h"
+
+
+static void rb_insert_callchain(struct rb_root *root, struct callchain_node *chain)
+{
+        struct rb_node **p = &root->rb_node;
+        struct rb_node *parent = NULL;
+        struct callchain_node *rnode;
+
+        while (*p) {
+                parent = *p;
+                rnode = rb_entry(parent, struct callchain_node, rb_node);
+
+                if (rnode->hit < chain->hit)
+                        p = &(*p)->rb_left;
+                else
+                        p = &(*p)->rb_right;
+        }
+
+        rb_link_node(&chain->rb_node, parent, p);
+        rb_insert_color(&chain->rb_node, root);
+}
+
+/*
+ * Once we get every callchains from the stream, we can now
+ * sort them by hit
+ */
+void sort_chain_to_rbtree(struct rb_root *rb_root, struct callchain_node *node)
+{
+        struct callchain_node *child;
+
+        list_for_each_entry(child, &node->children, brothers)
+                sort_chain_to_rbtree(rb_root, child);
+
+        if (node->hit)
+                rb_insert_callchain(rb_root, node);
+}
+
+static struct callchain_node *create_child(struct callchain_node *parent)
+{
+        struct callchain_node *new;
+
+        new = malloc(sizeof(*new));
+        if (!new) {
+                perror("not enough memory to create child for code path tree");
+                return NULL;
+        }
+        new->parent = parent;
+        INIT_LIST_HEAD(&new->children);
+        INIT_LIST_HEAD(&new->val);
+        list_add_tail(&new->brothers, &parent->children);
+
+        return new;
+}
+
+static void
+fill_node(struct callchain_node *node, struct ip_callchain *chain, int start)
+{
+        int i;
+
+        for (i = start; i < chain->nr; i++) {
+                struct callchain_list *call;
+
+                call = malloc(sizeof(*chain));
+                if (!call) {
+                        perror("not enough memory for the code path tree");
+                        return;
+                }
+                call->ip = chain->ips[i];
+                list_add_tail(&call->list, &node->val);
+        }
+        node->val_nr = i - start;
+}
+
+static void add_child(struct callchain_node *parent, struct ip_callchain *chain)
+{
+        struct callchain_node *new;
+
+        new = create_child(parent);
+        fill_node(new, chain, parent->val_nr);
+
+        new->hit = 1;
+}
+
+static void
+split_add_child(struct callchain_node *parent, struct ip_callchain *chain,
+                struct callchain_list *to_split, int idx)
+{
+        struct callchain_node *new;
+
+        /* split */
+        new = create_child(parent);
+        list_move_tail(&to_split->list, &new->val);
+        new->hit = parent->hit;
+        parent->hit = 0;
+        parent->val_nr = idx;
+
+        /* create the new one */
+        add_child(parent, chain);
+}
+
+static int
+__append_chain(struct callchain_node *root, struct ip_callchain *chain,
+                int start);
+
+static int
+__append_chain_children(struct callchain_node *root, struct ip_callchain *chain)
+{
+        struct callchain_node *rnode;
+
+        /* lookup in childrens */
+        list_for_each_entry(rnode, &root->children, brothers) {
+                int ret = __append_chain(rnode, chain, root->val_nr);
+                if (!ret)
+                        return 0;
+        }
+        return -1;
+}
+
+static int
+__append_chain(struct callchain_node *root, struct ip_callchain *chain,
+                int start)
+{
+        struct callchain_list *cnode;
+        int i = start;
+        bool found = false;
+
+        /* lookup in the current node */
+        list_for_each_entry(cnode, &root->val, list) {
+                if (cnode->ip != chain->ips[i++])
+                        break;
+                if (!found)
+                        found = true;
+                if (i == chain->nr)
+                        break;
+        }
+
+        /* matches not, relay on the parent */
+        if (!found)
+                return -1;
+
+        /* we match only a part of the node. Split it and add the new chain */
+        if (i < root->val_nr) {
+                split_add_child(root, chain, cnode, i);
+                return 0;
+        }
+
+        /* we match 100% of the path, increment the hit */
+        if (i == root->val_nr) {
+                root->hit++;
+                return 0;
+        }
+
+        return __append_chain_children(root, chain);
+}
+
+void append_chain(struct callchain_node *root, struct ip_callchain *chain)
+{
+        if (__append_chain_children(root, chain) == -1)
+                add_child(root, chain);
+}