Root/tools/perf/util/callchain.c

1/*
2 * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com>
3 *
4 * Handle the callchains from the stream in an ad-hoc radix tree and then
5 * sort them in an rbtree.
6 *
7 * Using a radix for code path provides a fast retrieval and factorizes
8 * memory use. Also that lets us use the paths in a hierarchical graph view.
9 *
10 */
11
12#include <stdlib.h>
13#include <stdio.h>
14#include <stdbool.h>
15#include <errno.h>
16#include <math.h>
17
18#include "callchain.h"
19
20#define chain_for_each_child(child, parent) \
21    list_for_each_entry(child, &parent->children, brothers)
22
23static void
24rb_insert_callchain(struct rb_root *root, struct callchain_node *chain,
25            enum chain_mode mode)
26{
27    struct rb_node **p = &root->rb_node;
28    struct rb_node *parent = NULL;
29    struct callchain_node *rnode;
30    u64 chain_cumul = cumul_hits(chain);
31
32    while (*p) {
33        u64 rnode_cumul;
34
35        parent = *p;
36        rnode = rb_entry(parent, struct callchain_node, rb_node);
37        rnode_cumul = cumul_hits(rnode);
38
39        switch (mode) {
40        case CHAIN_FLAT:
41            if (rnode->hit < chain->hit)
42                p = &(*p)->rb_left;
43            else
44                p = &(*p)->rb_right;
45            break;
46        case CHAIN_GRAPH_ABS: /* Falldown */
47        case CHAIN_GRAPH_REL:
48            if (rnode_cumul < chain_cumul)
49                p = &(*p)->rb_left;
50            else
51                p = &(*p)->rb_right;
52            break;
53        case CHAIN_NONE:
54        default:
55            break;
56        }
57    }
58
59    rb_link_node(&chain->rb_node, parent, p);
60    rb_insert_color(&chain->rb_node, root);
61}
62
63static void
64__sort_chain_flat(struct rb_root *rb_root, struct callchain_node *node,
65          u64 min_hit)
66{
67    struct callchain_node *child;
68
69    chain_for_each_child(child, node)
70        __sort_chain_flat(rb_root, child, min_hit);
71
72    if (node->hit && node->hit >= min_hit)
73        rb_insert_callchain(rb_root, node, CHAIN_FLAT);
74}
75
76/*
77 * Once we get every callchains from the stream, we can now
78 * sort them by hit
79 */
80static void
81sort_chain_flat(struct rb_root *rb_root, struct callchain_node *node,
82        u64 min_hit, struct callchain_param *param __used)
83{
84    __sort_chain_flat(rb_root, node, min_hit);
85}
86
87static void __sort_chain_graph_abs(struct callchain_node *node,
88                   u64 min_hit)
89{
90    struct callchain_node *child;
91
92    node->rb_root = RB_ROOT;
93
94    chain_for_each_child(child, node) {
95        __sort_chain_graph_abs(child, min_hit);
96        if (cumul_hits(child) >= min_hit)
97            rb_insert_callchain(&node->rb_root, child,
98                        CHAIN_GRAPH_ABS);
99    }
100}
101
102static void
103sort_chain_graph_abs(struct rb_root *rb_root, struct callchain_node *chain_root,
104             u64 min_hit, struct callchain_param *param __used)
105{
106    __sort_chain_graph_abs(chain_root, min_hit);
107    rb_root->rb_node = chain_root->rb_root.rb_node;
108}
109
110static void __sort_chain_graph_rel(struct callchain_node *node,
111                   double min_percent)
112{
113    struct callchain_node *child;
114    u64 min_hit;
115
116    node->rb_root = RB_ROOT;
117    min_hit = ceil(node->children_hit * min_percent);
118
119    chain_for_each_child(child, node) {
120        __sort_chain_graph_rel(child, min_percent);
121        if (cumul_hits(child) >= min_hit)
122            rb_insert_callchain(&node->rb_root, child,
123                        CHAIN_GRAPH_REL);
124    }
125}
126
127static void
128sort_chain_graph_rel(struct rb_root *rb_root, struct callchain_node *chain_root,
129             u64 min_hit __used, struct callchain_param *param)
130{
131    __sort_chain_graph_rel(chain_root, param->min_percent / 100.0);
132    rb_root->rb_node = chain_root->rb_root.rb_node;
133}
134
135int register_callchain_param(struct callchain_param *param)
136{
137    switch (param->mode) {
138    case CHAIN_GRAPH_ABS:
139        param->sort = sort_chain_graph_abs;
140        break;
141    case CHAIN_GRAPH_REL:
142        param->sort = sort_chain_graph_rel;
143        break;
144    case CHAIN_FLAT:
145        param->sort = sort_chain_flat;
146        break;
147    case CHAIN_NONE:
148    default:
149        return -1;
150    }
151    return 0;
152}
153
154/*
155 * Create a child for a parent. If inherit_children, then the new child
156 * will become the new parent of it's parent children
157 */
158static struct callchain_node *
159create_child(struct callchain_node *parent, bool inherit_children)
160{
161    struct callchain_node *new;
162
163    new = malloc(sizeof(*new));
164    if (!new) {
165        perror("not enough memory to create child for code path tree");
166        return NULL;
167    }
168    new->parent = parent;
169    INIT_LIST_HEAD(&new->children);
170    INIT_LIST_HEAD(&new->val);
171
172    if (inherit_children) {
173        struct callchain_node *next;
174
175        list_splice(&parent->children, &new->children);
176        INIT_LIST_HEAD(&parent->children);
177
178        chain_for_each_child(next, new)
179            next->parent = new;
180    }
181    list_add_tail(&new->brothers, &parent->children);
182
183    return new;
184}
185
186/*
187 * Fill the node with callchain values
188 */
189static void
190fill_node(struct callchain_node *node, struct ip_callchain *chain,
191      int start, struct symbol **syms)
192{
193    unsigned int i;
194
195    for (i = start; i < chain->nr; i++) {
196        struct callchain_list *call;
197
198        call = malloc(sizeof(*call));
199        if (!call) {
200            perror("not enough memory for the code path tree");
201            return;
202        }
203        call->ip = chain->ips[i];
204        call->sym = syms[i];
205        list_add_tail(&call->list, &node->val);
206    }
207    node->val_nr = chain->nr - start;
208    if (!node->val_nr)
209        pr_warning("Warning: empty node in callchain tree\n");
210}
211
212static void
213add_child(struct callchain_node *parent, struct ip_callchain *chain,
214      int start, struct symbol **syms)
215{
216    struct callchain_node *new;
217
218    new = create_child(parent, false);
219    fill_node(new, chain, start, syms);
220
221    new->children_hit = 0;
222    new->hit = 1;
223}
224
225/*
226 * Split the parent in two parts (a new child is created) and
227 * give a part of its callchain to the created child.
228 * Then create another child to host the given callchain of new branch
229 */
230static void
231split_add_child(struct callchain_node *parent, struct ip_callchain *chain,
232        struct callchain_list *to_split, int idx_parents, int idx_local,
233        struct symbol **syms)
234{
235    struct callchain_node *new;
236    struct list_head *old_tail;
237    unsigned int idx_total = idx_parents + idx_local;
238
239    /* split */
240    new = create_child(parent, true);
241
242    /* split the callchain and move a part to the new child */
243    old_tail = parent->val.prev;
244    list_del_range(&to_split->list, old_tail);
245    new->val.next = &to_split->list;
246    new->val.prev = old_tail;
247    to_split->list.prev = &new->val;
248    old_tail->next = &new->val;
249
250    /* split the hits */
251    new->hit = parent->hit;
252    new->children_hit = parent->children_hit;
253    parent->children_hit = cumul_hits(new);
254    new->val_nr = parent->val_nr - idx_local;
255    parent->val_nr = idx_local;
256
257    /* create a new child for the new branch if any */
258    if (idx_total < chain->nr) {
259        parent->hit = 0;
260        add_child(parent, chain, idx_total, syms);
261        parent->children_hit++;
262    } else {
263        parent->hit = 1;
264    }
265}
266
267static int
268__append_chain(struct callchain_node *root, struct ip_callchain *chain,
269           unsigned int start, struct symbol **syms);
270
271static void
272__append_chain_children(struct callchain_node *root, struct ip_callchain *chain,
273            struct symbol **syms, unsigned int start)
274{
275    struct callchain_node *rnode;
276
277    /* lookup in childrens */
278    chain_for_each_child(rnode, root) {
279        unsigned int ret = __append_chain(rnode, chain, start, syms);
280
281        if (!ret)
282            goto inc_children_hit;
283    }
284    /* nothing in children, add to the current node */
285    add_child(root, chain, start, syms);
286
287inc_children_hit:
288    root->children_hit++;
289}
290
291static int
292__append_chain(struct callchain_node *root, struct ip_callchain *chain,
293           unsigned int start, struct symbol **syms)
294{
295    struct callchain_list *cnode;
296    unsigned int i = start;
297    bool found = false;
298
299    /*
300     * Lookup in the current node
301     * If we have a symbol, then compare the start to match
302     * anywhere inside a function.
303     */
304    list_for_each_entry(cnode, &root->val, list) {
305        if (i == chain->nr)
306            break;
307        if (cnode->sym && syms[i]) {
308            if (cnode->sym->start != syms[i]->start)
309                break;
310        } else if (cnode->ip != chain->ips[i])
311            break;
312        if (!found)
313            found = true;
314        i++;
315    }
316
317    /* matches not, relay on the parent */
318    if (!found)
319        return -1;
320
321    /* we match only a part of the node. Split it and add the new chain */
322    if (i - start < root->val_nr) {
323        split_add_child(root, chain, cnode, start, i - start, syms);
324        return 0;
325    }
326
327    /* we match 100% of the path, increment the hit */
328    if (i - start == root->val_nr && i == chain->nr) {
329        root->hit++;
330        return 0;
331    }
332
333    /* We match the node and still have a part remaining */
334    __append_chain_children(root, chain, syms, i);
335
336    return 0;
337}
338
339void append_chain(struct callchain_node *root, struct ip_callchain *chain,
340          struct symbol **syms)
341{
342    if (!chain->nr)
343        return;
344    __append_chain_children(root, chain, syms, 0);
345}
346

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