1 /*
2 * Copyright (C) 2009-2011, 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 "hist.h"
19 #include "util.h"
20 #include "callchain.h"
21
22 __thread struct callchain_cursor callchain_cursor;
23
24 #define chain_for_each_child(child, parent) \
25 list_for_each_entry(child, &parent->children, siblings)
26
27 #define chain_for_each_child_safe(child, next, parent) \
28 list_for_each_entry_safe(child, next, &parent->children, siblings)
29
30 static void
rb_insert_callchain(struct rb_root * root,struct callchain_node * chain,enum chain_mode mode)31 rb_insert_callchain(struct rb_root *root, struct callchain_node *chain,
32 enum chain_mode mode)
33 {
34 struct rb_node **p = &root->rb_node;
35 struct rb_node *parent = NULL;
36 struct callchain_node *rnode;
37 u64 chain_cumul = callchain_cumul_hits(chain);
38
39 while (*p) {
40 u64 rnode_cumul;
41
42 parent = *p;
43 rnode = rb_entry(parent, struct callchain_node, rb_node);
44 rnode_cumul = callchain_cumul_hits(rnode);
45
46 switch (mode) {
47 case CHAIN_FLAT:
48 if (rnode->hit < chain->hit)
49 p = &(*p)->rb_left;
50 else
51 p = &(*p)->rb_right;
52 break;
53 case CHAIN_GRAPH_ABS: /* Falldown */
54 case CHAIN_GRAPH_REL:
55 if (rnode_cumul < chain_cumul)
56 p = &(*p)->rb_left;
57 else
58 p = &(*p)->rb_right;
59 break;
60 case CHAIN_NONE:
61 default:
62 break;
63 }
64 }
65
66 rb_link_node(&chain->rb_node, parent, p);
67 rb_insert_color(&chain->rb_node, root);
68 }
69
70 static void
__sort_chain_flat(struct rb_root * rb_root,struct callchain_node * node,u64 min_hit)71 __sort_chain_flat(struct rb_root *rb_root, struct callchain_node *node,
72 u64 min_hit)
73 {
74 struct callchain_node *child;
75
76 chain_for_each_child(child, node)
77 __sort_chain_flat(rb_root, child, min_hit);
78
79 if (node->hit && node->hit >= min_hit)
80 rb_insert_callchain(rb_root, node, CHAIN_FLAT);
81 }
82
83 /*
84 * Once we get every callchains from the stream, we can now
85 * sort them by hit
86 */
87 static void
sort_chain_flat(struct rb_root * rb_root,struct callchain_root * root,u64 min_hit,struct callchain_param * param __maybe_unused)88 sort_chain_flat(struct rb_root *rb_root, struct callchain_root *root,
89 u64 min_hit, struct callchain_param *param __maybe_unused)
90 {
91 __sort_chain_flat(rb_root, &root->node, min_hit);
92 }
93
__sort_chain_graph_abs(struct callchain_node * node,u64 min_hit)94 static void __sort_chain_graph_abs(struct callchain_node *node,
95 u64 min_hit)
96 {
97 struct callchain_node *child;
98
99 node->rb_root = RB_ROOT;
100
101 chain_for_each_child(child, node) {
102 __sort_chain_graph_abs(child, min_hit);
103 if (callchain_cumul_hits(child) >= min_hit)
104 rb_insert_callchain(&node->rb_root, child,
105 CHAIN_GRAPH_ABS);
106 }
107 }
108
109 static void
sort_chain_graph_abs(struct rb_root * rb_root,struct callchain_root * chain_root,u64 min_hit,struct callchain_param * param __maybe_unused)110 sort_chain_graph_abs(struct rb_root *rb_root, struct callchain_root *chain_root,
111 u64 min_hit, struct callchain_param *param __maybe_unused)
112 {
113 __sort_chain_graph_abs(&chain_root->node, min_hit);
114 rb_root->rb_node = chain_root->node.rb_root.rb_node;
115 }
116
__sort_chain_graph_rel(struct callchain_node * node,double min_percent)117 static void __sort_chain_graph_rel(struct callchain_node *node,
118 double min_percent)
119 {
120 struct callchain_node *child;
121 u64 min_hit;
122
123 node->rb_root = RB_ROOT;
124 min_hit = ceil(node->children_hit * min_percent);
125
126 chain_for_each_child(child, node) {
127 __sort_chain_graph_rel(child, min_percent);
128 if (callchain_cumul_hits(child) >= min_hit)
129 rb_insert_callchain(&node->rb_root, child,
130 CHAIN_GRAPH_REL);
131 }
132 }
133
134 static void
sort_chain_graph_rel(struct rb_root * rb_root,struct callchain_root * chain_root,u64 min_hit __maybe_unused,struct callchain_param * param)135 sort_chain_graph_rel(struct rb_root *rb_root, struct callchain_root *chain_root,
136 u64 min_hit __maybe_unused, struct callchain_param *param)
137 {
138 __sort_chain_graph_rel(&chain_root->node, param->min_percent / 100.0);
139 rb_root->rb_node = chain_root->node.rb_root.rb_node;
140 }
141
callchain_register_param(struct callchain_param * param)142 int callchain_register_param(struct callchain_param *param)
143 {
144 switch (param->mode) {
145 case CHAIN_GRAPH_ABS:
146 param->sort = sort_chain_graph_abs;
147 break;
148 case CHAIN_GRAPH_REL:
149 param->sort = sort_chain_graph_rel;
150 break;
151 case CHAIN_FLAT:
152 param->sort = sort_chain_flat;
153 break;
154 case CHAIN_NONE:
155 default:
156 return -1;
157 }
158 return 0;
159 }
160
161 /*
162 * Create a child for a parent. If inherit_children, then the new child
163 * will become the new parent of it's parent children
164 */
165 static struct callchain_node *
create_child(struct callchain_node * parent,bool inherit_children)166 create_child(struct callchain_node *parent, bool inherit_children)
167 {
168 struct callchain_node *new;
169
170 new = zalloc(sizeof(*new));
171 if (!new) {
172 perror("not enough memory to create child for code path tree");
173 return NULL;
174 }
175 new->parent = parent;
176 INIT_LIST_HEAD(&new->children);
177 INIT_LIST_HEAD(&new->val);
178
179 if (inherit_children) {
180 struct callchain_node *next;
181
182 list_splice(&parent->children, &new->children);
183 INIT_LIST_HEAD(&parent->children);
184
185 chain_for_each_child(next, new)
186 next->parent = new;
187 }
188 list_add_tail(&new->siblings, &parent->children);
189
190 return new;
191 }
192
193
194 /*
195 * Fill the node with callchain values
196 */
197 static void
fill_node(struct callchain_node * node,struct callchain_cursor * cursor)198 fill_node(struct callchain_node *node, struct callchain_cursor *cursor)
199 {
200 struct callchain_cursor_node *cursor_node;
201
202 node->val_nr = cursor->nr - cursor->pos;
203 if (!node->val_nr)
204 pr_warning("Warning: empty node in callchain tree\n");
205
206 cursor_node = callchain_cursor_current(cursor);
207
208 while (cursor_node) {
209 struct callchain_list *call;
210
211 call = zalloc(sizeof(*call));
212 if (!call) {
213 perror("not enough memory for the code path tree");
214 return;
215 }
216 call->ip = cursor_node->ip;
217 call->ms.sym = cursor_node->sym;
218 call->ms.map = cursor_node->map;
219 list_add_tail(&call->list, &node->val);
220
221 callchain_cursor_advance(cursor);
222 cursor_node = callchain_cursor_current(cursor);
223 }
224 }
225
226 static void
add_child(struct callchain_node * parent,struct callchain_cursor * cursor,u64 period)227 add_child(struct callchain_node *parent,
228 struct callchain_cursor *cursor,
229 u64 period)
230 {
231 struct callchain_node *new;
232
233 new = create_child(parent, false);
234 fill_node(new, cursor);
235
236 new->children_hit = 0;
237 new->hit = period;
238 }
239
240 /*
241 * Split the parent in two parts (a new child is created) and
242 * give a part of its callchain to the created child.
243 * Then create another child to host the given callchain of new branch
244 */
245 static void
split_add_child(struct callchain_node * parent,struct callchain_cursor * cursor,struct callchain_list * to_split,u64 idx_parents,u64 idx_local,u64 period)246 split_add_child(struct callchain_node *parent,
247 struct callchain_cursor *cursor,
248 struct callchain_list *to_split,
249 u64 idx_parents, u64 idx_local, u64 period)
250 {
251 struct callchain_node *new;
252 struct list_head *old_tail;
253 unsigned int idx_total = idx_parents + idx_local;
254
255 /* split */
256 new = create_child(parent, true);
257
258 /* split the callchain and move a part to the new child */
259 old_tail = parent->val.prev;
260 list_del_range(&to_split->list, old_tail);
261 new->val.next = &to_split->list;
262 new->val.prev = old_tail;
263 to_split->list.prev = &new->val;
264 old_tail->next = &new->val;
265
266 /* split the hits */
267 new->hit = parent->hit;
268 new->children_hit = parent->children_hit;
269 parent->children_hit = callchain_cumul_hits(new);
270 new->val_nr = parent->val_nr - idx_local;
271 parent->val_nr = idx_local;
272
273 /* create a new child for the new branch if any */
274 if (idx_total < cursor->nr) {
275 parent->hit = 0;
276 add_child(parent, cursor, period);
277 parent->children_hit += period;
278 } else {
279 parent->hit = period;
280 }
281 }
282
283 static int
284 append_chain(struct callchain_node *root,
285 struct callchain_cursor *cursor,
286 u64 period);
287
288 static void
append_chain_children(struct callchain_node * root,struct callchain_cursor * cursor,u64 period)289 append_chain_children(struct callchain_node *root,
290 struct callchain_cursor *cursor,
291 u64 period)
292 {
293 struct callchain_node *rnode;
294
295 /* lookup in childrens */
296 chain_for_each_child(rnode, root) {
297 unsigned int ret = append_chain(rnode, cursor, period);
298
299 if (!ret)
300 goto inc_children_hit;
301 }
302 /* nothing in children, add to the current node */
303 add_child(root, cursor, period);
304
305 inc_children_hit:
306 root->children_hit += period;
307 }
308
309 static int
append_chain(struct callchain_node * root,struct callchain_cursor * cursor,u64 period)310 append_chain(struct callchain_node *root,
311 struct callchain_cursor *cursor,
312 u64 period)
313 {
314 struct callchain_cursor_node *curr_snap = cursor->curr;
315 struct callchain_list *cnode;
316 u64 start = cursor->pos;
317 bool found = false;
318 u64 matches;
319
320 /*
321 * Lookup in the current node
322 * If we have a symbol, then compare the start to match
323 * anywhere inside a function, unless function
324 * mode is disabled.
325 */
326 list_for_each_entry(cnode, &root->val, list) {
327 struct callchain_cursor_node *node;
328 struct symbol *sym;
329
330 node = callchain_cursor_current(cursor);
331 if (!node)
332 break;
333
334 sym = node->sym;
335
336 if (cnode->ms.sym && sym &&
337 callchain_param.key == CCKEY_FUNCTION) {
338 if (cnode->ms.sym->start != sym->start)
339 break;
340 } else if (cnode->ip != node->ip)
341 break;
342
343 if (!found)
344 found = true;
345
346 callchain_cursor_advance(cursor);
347 }
348
349 /* matches not, relay on the parent */
350 if (!found) {
351 cursor->curr = curr_snap;
352 cursor->pos = start;
353 return -1;
354 }
355
356 matches = cursor->pos - start;
357
358 /* we match only a part of the node. Split it and add the new chain */
359 if (matches < root->val_nr) {
360 split_add_child(root, cursor, cnode, start, matches, period);
361 return 0;
362 }
363
364 /* we match 100% of the path, increment the hit */
365 if (matches == root->val_nr && cursor->pos == cursor->nr) {
366 root->hit += period;
367 return 0;
368 }
369
370 /* We match the node and still have a part remaining */
371 append_chain_children(root, cursor, period);
372
373 return 0;
374 }
375
callchain_append(struct callchain_root * root,struct callchain_cursor * cursor,u64 period)376 int callchain_append(struct callchain_root *root,
377 struct callchain_cursor *cursor,
378 u64 period)
379 {
380 if (!cursor->nr)
381 return 0;
382
383 callchain_cursor_commit(cursor);
384
385 append_chain_children(&root->node, cursor, period);
386
387 if (cursor->nr > root->max_depth)
388 root->max_depth = cursor->nr;
389
390 return 0;
391 }
392
393 static int
merge_chain_branch(struct callchain_cursor * cursor,struct callchain_node * dst,struct callchain_node * src)394 merge_chain_branch(struct callchain_cursor *cursor,
395 struct callchain_node *dst, struct callchain_node *src)
396 {
397 struct callchain_cursor_node **old_last = cursor->last;
398 struct callchain_node *child, *next_child;
399 struct callchain_list *list, *next_list;
400 int old_pos = cursor->nr;
401 int err = 0;
402
403 list_for_each_entry_safe(list, next_list, &src->val, list) {
404 callchain_cursor_append(cursor, list->ip,
405 list->ms.map, list->ms.sym);
406 list_del(&list->list);
407 free(list);
408 }
409
410 if (src->hit) {
411 callchain_cursor_commit(cursor);
412 append_chain_children(dst, cursor, src->hit);
413 }
414
415 chain_for_each_child_safe(child, next_child, src) {
416 err = merge_chain_branch(cursor, dst, child);
417 if (err)
418 break;
419
420 list_del(&child->siblings);
421 free(child);
422 }
423
424 cursor->nr = old_pos;
425 cursor->last = old_last;
426
427 return err;
428 }
429
callchain_merge(struct callchain_cursor * cursor,struct callchain_root * dst,struct callchain_root * src)430 int callchain_merge(struct callchain_cursor *cursor,
431 struct callchain_root *dst, struct callchain_root *src)
432 {
433 return merge_chain_branch(cursor, &dst->node, &src->node);
434 }
435
callchain_cursor_append(struct callchain_cursor * cursor,u64 ip,struct map * map,struct symbol * sym)436 int callchain_cursor_append(struct callchain_cursor *cursor,
437 u64 ip, struct map *map, struct symbol *sym)
438 {
439 struct callchain_cursor_node *node = *cursor->last;
440
441 if (!node) {
442 node = calloc(1, sizeof(*node));
443 if (!node)
444 return -ENOMEM;
445
446 *cursor->last = node;
447 }
448
449 node->ip = ip;
450 node->map = map;
451 node->sym = sym;
452
453 cursor->nr++;
454
455 cursor->last = &node->next;
456
457 return 0;
458 }
459