Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/kernel/profile.c | |
3 | * Simple profiling. Manages a direct-mapped profile hit count buffer, | |
4 | * with configurable resolution, support for restricting the cpus on | |
5 | * which profiling is done, and switching between cpu time and | |
6 | * schedule() calls via kernel command line parameters passed at boot. | |
7 | * | |
8 | * Scheduler profiling support, Arjan van de Ven and Ingo Molnar, | |
9 | * Red Hat, July 2004 | |
10 | * Consolidation of architecture support code for profiling, | |
11 | * William Irwin, Oracle, July 2004 | |
12 | * Amortized hit count accounting via per-cpu open-addressed hashtables | |
13 | * to resolve timer interrupt livelocks, William Irwin, Oracle, 2004 | |
14 | */ | |
15 | ||
16 | #include <linux/config.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/profile.h> | |
19 | #include <linux/bootmem.h> | |
20 | #include <linux/notifier.h> | |
21 | #include <linux/mm.h> | |
22 | #include <linux/cpumask.h> | |
23 | #include <linux/cpu.h> | |
24 | #include <linux/profile.h> | |
25 | #include <linux/highmem.h> | |
97d1f15b | 26 | #include <linux/mutex.h> |
1da177e4 LT |
27 | #include <asm/sections.h> |
28 | #include <asm/semaphore.h> | |
29 | ||
30 | struct profile_hit { | |
31 | u32 pc, hits; | |
32 | }; | |
33 | #define PROFILE_GRPSHIFT 3 | |
34 | #define PROFILE_GRPSZ (1 << PROFILE_GRPSHIFT) | |
35 | #define NR_PROFILE_HIT (PAGE_SIZE/sizeof(struct profile_hit)) | |
36 | #define NR_PROFILE_GRP (NR_PROFILE_HIT/PROFILE_GRPSZ) | |
37 | ||
38 | /* Oprofile timer tick hook */ | |
6c036527 | 39 | int (*timer_hook)(struct pt_regs *) __read_mostly; |
1da177e4 LT |
40 | |
41 | static atomic_t *prof_buffer; | |
42 | static unsigned long prof_len, prof_shift; | |
6c036527 | 43 | static int prof_on __read_mostly; |
1da177e4 LT |
44 | static cpumask_t prof_cpu_mask = CPU_MASK_ALL; |
45 | #ifdef CONFIG_SMP | |
46 | static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits); | |
47 | static DEFINE_PER_CPU(int, cpu_profile_flip); | |
97d1f15b | 48 | static DEFINE_MUTEX(profile_flip_mutex); |
1da177e4 LT |
49 | #endif /* CONFIG_SMP */ |
50 | ||
51 | static int __init profile_setup(char * str) | |
52 | { | |
dfaa9c94 | 53 | static char __initdata schedstr[] = "schedule"; |
1da177e4 LT |
54 | int par; |
55 | ||
dfaa9c94 | 56 | if (!strncmp(str, schedstr, strlen(schedstr))) { |
1da177e4 | 57 | prof_on = SCHED_PROFILING; |
dfaa9c94 WLII |
58 | if (str[strlen(schedstr)] == ',') |
59 | str += strlen(schedstr) + 1; | |
60 | if (get_option(&str, &par)) | |
61 | prof_shift = par; | |
62 | printk(KERN_INFO | |
63 | "kernel schedule profiling enabled (shift: %ld)\n", | |
64 | prof_shift); | |
65 | } else if (get_option(&str, &par)) { | |
1da177e4 LT |
66 | prof_shift = par; |
67 | prof_on = CPU_PROFILING; | |
68 | printk(KERN_INFO "kernel profiling enabled (shift: %ld)\n", | |
69 | prof_shift); | |
70 | } | |
71 | return 1; | |
72 | } | |
73 | __setup("profile=", profile_setup); | |
74 | ||
75 | ||
76 | void __init profile_init(void) | |
77 | { | |
78 | if (!prof_on) | |
79 | return; | |
80 | ||
81 | /* only text is profiled */ | |
82 | prof_len = (_etext - _stext) >> prof_shift; | |
83 | prof_buffer = alloc_bootmem(prof_len*sizeof(atomic_t)); | |
84 | } | |
85 | ||
86 | /* Profile event notifications */ | |
87 | ||
88 | #ifdef CONFIG_PROFILING | |
89 | ||
e041c683 AS |
90 | static BLOCKING_NOTIFIER_HEAD(task_exit_notifier); |
91 | static ATOMIC_NOTIFIER_HEAD(task_free_notifier); | |
92 | static BLOCKING_NOTIFIER_HEAD(munmap_notifier); | |
1da177e4 LT |
93 | |
94 | void profile_task_exit(struct task_struct * task) | |
95 | { | |
e041c683 | 96 | blocking_notifier_call_chain(&task_exit_notifier, 0, task); |
1da177e4 LT |
97 | } |
98 | ||
99 | int profile_handoff_task(struct task_struct * task) | |
100 | { | |
101 | int ret; | |
e041c683 | 102 | ret = atomic_notifier_call_chain(&task_free_notifier, 0, task); |
1da177e4 LT |
103 | return (ret == NOTIFY_OK) ? 1 : 0; |
104 | } | |
105 | ||
106 | void profile_munmap(unsigned long addr) | |
107 | { | |
e041c683 | 108 | blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr); |
1da177e4 LT |
109 | } |
110 | ||
111 | int task_handoff_register(struct notifier_block * n) | |
112 | { | |
e041c683 | 113 | return atomic_notifier_chain_register(&task_free_notifier, n); |
1da177e4 LT |
114 | } |
115 | ||
116 | int task_handoff_unregister(struct notifier_block * n) | |
117 | { | |
e041c683 | 118 | return atomic_notifier_chain_unregister(&task_free_notifier, n); |
1da177e4 LT |
119 | } |
120 | ||
121 | int profile_event_register(enum profile_type type, struct notifier_block * n) | |
122 | { | |
123 | int err = -EINVAL; | |
124 | ||
1da177e4 LT |
125 | switch (type) { |
126 | case PROFILE_TASK_EXIT: | |
e041c683 AS |
127 | err = blocking_notifier_chain_register( |
128 | &task_exit_notifier, n); | |
1da177e4 LT |
129 | break; |
130 | case PROFILE_MUNMAP: | |
e041c683 AS |
131 | err = blocking_notifier_chain_register( |
132 | &munmap_notifier, n); | |
1da177e4 LT |
133 | break; |
134 | } | |
135 | ||
1da177e4 LT |
136 | return err; |
137 | } | |
138 | ||
139 | ||
140 | int profile_event_unregister(enum profile_type type, struct notifier_block * n) | |
141 | { | |
142 | int err = -EINVAL; | |
143 | ||
1da177e4 LT |
144 | switch (type) { |
145 | case PROFILE_TASK_EXIT: | |
e041c683 AS |
146 | err = blocking_notifier_chain_unregister( |
147 | &task_exit_notifier, n); | |
1da177e4 LT |
148 | break; |
149 | case PROFILE_MUNMAP: | |
e041c683 AS |
150 | err = blocking_notifier_chain_unregister( |
151 | &munmap_notifier, n); | |
1da177e4 LT |
152 | break; |
153 | } | |
154 | ||
1da177e4 LT |
155 | return err; |
156 | } | |
157 | ||
158 | int register_timer_hook(int (*hook)(struct pt_regs *)) | |
159 | { | |
160 | if (timer_hook) | |
161 | return -EBUSY; | |
162 | timer_hook = hook; | |
163 | return 0; | |
164 | } | |
165 | ||
166 | void unregister_timer_hook(int (*hook)(struct pt_regs *)) | |
167 | { | |
168 | WARN_ON(hook != timer_hook); | |
169 | timer_hook = NULL; | |
170 | /* make sure all CPUs see the NULL hook */ | |
fbd568a3 | 171 | synchronize_sched(); /* Allow ongoing interrupts to complete. */ |
1da177e4 LT |
172 | } |
173 | ||
174 | EXPORT_SYMBOL_GPL(register_timer_hook); | |
175 | EXPORT_SYMBOL_GPL(unregister_timer_hook); | |
176 | EXPORT_SYMBOL_GPL(task_handoff_register); | |
177 | EXPORT_SYMBOL_GPL(task_handoff_unregister); | |
178 | ||
179 | #endif /* CONFIG_PROFILING */ | |
180 | ||
181 | EXPORT_SYMBOL_GPL(profile_event_register); | |
182 | EXPORT_SYMBOL_GPL(profile_event_unregister); | |
183 | ||
184 | #ifdef CONFIG_SMP | |
185 | /* | |
186 | * Each cpu has a pair of open-addressed hashtables for pending | |
187 | * profile hits. read_profile() IPI's all cpus to request them | |
188 | * to flip buffers and flushes their contents to prof_buffer itself. | |
189 | * Flip requests are serialized by the profile_flip_mutex. The sole | |
190 | * use of having a second hashtable is for avoiding cacheline | |
191 | * contention that would otherwise happen during flushes of pending | |
192 | * profile hits required for the accuracy of reported profile hits | |
193 | * and so resurrect the interrupt livelock issue. | |
194 | * | |
195 | * The open-addressed hashtables are indexed by profile buffer slot | |
196 | * and hold the number of pending hits to that profile buffer slot on | |
197 | * a cpu in an entry. When the hashtable overflows, all pending hits | |
198 | * are accounted to their corresponding profile buffer slots with | |
199 | * atomic_add() and the hashtable emptied. As numerous pending hits | |
200 | * may be accounted to a profile buffer slot in a hashtable entry, | |
201 | * this amortizes a number of atomic profile buffer increments likely | |
202 | * to be far larger than the number of entries in the hashtable, | |
203 | * particularly given that the number of distinct profile buffer | |
204 | * positions to which hits are accounted during short intervals (e.g. | |
205 | * several seconds) is usually very small. Exclusion from buffer | |
206 | * flipping is provided by interrupt disablement (note that for | |
207 | * SCHED_PROFILING profile_hit() may be called from process context). | |
208 | * The hash function is meant to be lightweight as opposed to strong, | |
209 | * and was vaguely inspired by ppc64 firmware-supported inverted | |
210 | * pagetable hash functions, but uses a full hashtable full of finite | |
211 | * collision chains, not just pairs of them. | |
212 | * | |
213 | * -- wli | |
214 | */ | |
215 | static void __profile_flip_buffers(void *unused) | |
216 | { | |
217 | int cpu = smp_processor_id(); | |
218 | ||
219 | per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu); | |
220 | } | |
221 | ||
222 | static void profile_flip_buffers(void) | |
223 | { | |
224 | int i, j, cpu; | |
225 | ||
97d1f15b | 226 | mutex_lock(&profile_flip_mutex); |
1da177e4 LT |
227 | j = per_cpu(cpu_profile_flip, get_cpu()); |
228 | put_cpu(); | |
229 | on_each_cpu(__profile_flip_buffers, NULL, 0, 1); | |
230 | for_each_online_cpu(cpu) { | |
231 | struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j]; | |
232 | for (i = 0; i < NR_PROFILE_HIT; ++i) { | |
233 | if (!hits[i].hits) { | |
234 | if (hits[i].pc) | |
235 | hits[i].pc = 0; | |
236 | continue; | |
237 | } | |
238 | atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]); | |
239 | hits[i].hits = hits[i].pc = 0; | |
240 | } | |
241 | } | |
97d1f15b | 242 | mutex_unlock(&profile_flip_mutex); |
1da177e4 LT |
243 | } |
244 | ||
245 | static void profile_discard_flip_buffers(void) | |
246 | { | |
247 | int i, cpu; | |
248 | ||
97d1f15b | 249 | mutex_lock(&profile_flip_mutex); |
1da177e4 LT |
250 | i = per_cpu(cpu_profile_flip, get_cpu()); |
251 | put_cpu(); | |
252 | on_each_cpu(__profile_flip_buffers, NULL, 0, 1); | |
253 | for_each_online_cpu(cpu) { | |
254 | struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i]; | |
255 | memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit)); | |
256 | } | |
97d1f15b | 257 | mutex_unlock(&profile_flip_mutex); |
1da177e4 LT |
258 | } |
259 | ||
260 | void profile_hit(int type, void *__pc) | |
261 | { | |
262 | unsigned long primary, secondary, flags, pc = (unsigned long)__pc; | |
263 | int i, j, cpu; | |
264 | struct profile_hit *hits; | |
265 | ||
266 | if (prof_on != type || !prof_buffer) | |
267 | return; | |
268 | pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1); | |
269 | i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT; | |
270 | secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT; | |
271 | cpu = get_cpu(); | |
272 | hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)]; | |
273 | if (!hits) { | |
274 | put_cpu(); | |
275 | return; | |
276 | } | |
277 | local_irq_save(flags); | |
278 | do { | |
279 | for (j = 0; j < PROFILE_GRPSZ; ++j) { | |
280 | if (hits[i + j].pc == pc) { | |
281 | hits[i + j].hits++; | |
282 | goto out; | |
283 | } else if (!hits[i + j].hits) { | |
284 | hits[i + j].pc = pc; | |
285 | hits[i + j].hits = 1; | |
286 | goto out; | |
287 | } | |
288 | } | |
289 | i = (i + secondary) & (NR_PROFILE_HIT - 1); | |
290 | } while (i != primary); | |
291 | atomic_inc(&prof_buffer[pc]); | |
292 | for (i = 0; i < NR_PROFILE_HIT; ++i) { | |
293 | atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]); | |
294 | hits[i].pc = hits[i].hits = 0; | |
295 | } | |
296 | out: | |
297 | local_irq_restore(flags); | |
298 | put_cpu(); | |
299 | } | |
300 | ||
301 | #ifdef CONFIG_HOTPLUG_CPU | |
83d722f7 | 302 | static int profile_cpu_callback(struct notifier_block *info, |
1da177e4 LT |
303 | unsigned long action, void *__cpu) |
304 | { | |
305 | int node, cpu = (unsigned long)__cpu; | |
306 | struct page *page; | |
307 | ||
308 | switch (action) { | |
309 | case CPU_UP_PREPARE: | |
310 | node = cpu_to_node(cpu); | |
311 | per_cpu(cpu_profile_flip, cpu) = 0; | |
312 | if (!per_cpu(cpu_profile_hits, cpu)[1]) { | |
313 | page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0); | |
314 | if (!page) | |
315 | return NOTIFY_BAD; | |
316 | per_cpu(cpu_profile_hits, cpu)[1] = page_address(page); | |
317 | } | |
318 | if (!per_cpu(cpu_profile_hits, cpu)[0]) { | |
319 | page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0); | |
320 | if (!page) | |
321 | goto out_free; | |
322 | per_cpu(cpu_profile_hits, cpu)[0] = page_address(page); | |
323 | } | |
324 | break; | |
325 | out_free: | |
326 | page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]); | |
327 | per_cpu(cpu_profile_hits, cpu)[1] = NULL; | |
328 | __free_page(page); | |
329 | return NOTIFY_BAD; | |
330 | case CPU_ONLINE: | |
331 | cpu_set(cpu, prof_cpu_mask); | |
332 | break; | |
333 | case CPU_UP_CANCELED: | |
334 | case CPU_DEAD: | |
335 | cpu_clear(cpu, prof_cpu_mask); | |
336 | if (per_cpu(cpu_profile_hits, cpu)[0]) { | |
337 | page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]); | |
338 | per_cpu(cpu_profile_hits, cpu)[0] = NULL; | |
339 | __free_page(page); | |
340 | } | |
341 | if (per_cpu(cpu_profile_hits, cpu)[1]) { | |
342 | page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]); | |
343 | per_cpu(cpu_profile_hits, cpu)[1] = NULL; | |
344 | __free_page(page); | |
345 | } | |
346 | break; | |
347 | } | |
348 | return NOTIFY_OK; | |
349 | } | |
350 | #endif /* CONFIG_HOTPLUG_CPU */ | |
351 | #else /* !CONFIG_SMP */ | |
352 | #define profile_flip_buffers() do { } while (0) | |
353 | #define profile_discard_flip_buffers() do { } while (0) | |
354 | ||
355 | void profile_hit(int type, void *__pc) | |
356 | { | |
357 | unsigned long pc; | |
358 | ||
359 | if (prof_on != type || !prof_buffer) | |
360 | return; | |
361 | pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift; | |
362 | atomic_inc(&prof_buffer[min(pc, prof_len - 1)]); | |
363 | } | |
364 | #endif /* !CONFIG_SMP */ | |
365 | ||
366 | void profile_tick(int type, struct pt_regs *regs) | |
367 | { | |
368 | if (type == CPU_PROFILING && timer_hook) | |
369 | timer_hook(regs); | |
370 | if (!user_mode(regs) && cpu_isset(smp_processor_id(), prof_cpu_mask)) | |
371 | profile_hit(type, (void *)profile_pc(regs)); | |
372 | } | |
373 | ||
374 | #ifdef CONFIG_PROC_FS | |
375 | #include <linux/proc_fs.h> | |
376 | #include <asm/uaccess.h> | |
377 | #include <asm/ptrace.h> | |
378 | ||
379 | static int prof_cpu_mask_read_proc (char *page, char **start, off_t off, | |
380 | int count, int *eof, void *data) | |
381 | { | |
382 | int len = cpumask_scnprintf(page, count, *(cpumask_t *)data); | |
383 | if (count - len < 2) | |
384 | return -EINVAL; | |
385 | len += sprintf(page + len, "\n"); | |
386 | return len; | |
387 | } | |
388 | ||
389 | static int prof_cpu_mask_write_proc (struct file *file, const char __user *buffer, | |
390 | unsigned long count, void *data) | |
391 | { | |
392 | cpumask_t *mask = (cpumask_t *)data; | |
393 | unsigned long full_count = count, err; | |
394 | cpumask_t new_value; | |
395 | ||
396 | err = cpumask_parse(buffer, count, new_value); | |
397 | if (err) | |
398 | return err; | |
399 | ||
400 | *mask = new_value; | |
401 | return full_count; | |
402 | } | |
403 | ||
404 | void create_prof_cpu_mask(struct proc_dir_entry *root_irq_dir) | |
405 | { | |
406 | struct proc_dir_entry *entry; | |
407 | ||
408 | /* create /proc/irq/prof_cpu_mask */ | |
409 | if (!(entry = create_proc_entry("prof_cpu_mask", 0600, root_irq_dir))) | |
410 | return; | |
411 | entry->nlink = 1; | |
412 | entry->data = (void *)&prof_cpu_mask; | |
413 | entry->read_proc = prof_cpu_mask_read_proc; | |
414 | entry->write_proc = prof_cpu_mask_write_proc; | |
415 | } | |
416 | ||
417 | /* | |
418 | * This function accesses profiling information. The returned data is | |
419 | * binary: the sampling step and the actual contents of the profile | |
420 | * buffer. Use of the program readprofile is recommended in order to | |
421 | * get meaningful info out of these data. | |
422 | */ | |
423 | static ssize_t | |
424 | read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos) | |
425 | { | |
426 | unsigned long p = *ppos; | |
427 | ssize_t read; | |
428 | char * pnt; | |
429 | unsigned int sample_step = 1 << prof_shift; | |
430 | ||
431 | profile_flip_buffers(); | |
432 | if (p >= (prof_len+1)*sizeof(unsigned int)) | |
433 | return 0; | |
434 | if (count > (prof_len+1)*sizeof(unsigned int) - p) | |
435 | count = (prof_len+1)*sizeof(unsigned int) - p; | |
436 | read = 0; | |
437 | ||
438 | while (p < sizeof(unsigned int) && count > 0) { | |
439 | put_user(*((char *)(&sample_step)+p),buf); | |
440 | buf++; p++; count--; read++; | |
441 | } | |
442 | pnt = (char *)prof_buffer + p - sizeof(atomic_t); | |
443 | if (copy_to_user(buf,(void *)pnt,count)) | |
444 | return -EFAULT; | |
445 | read += count; | |
446 | *ppos += read; | |
447 | return read; | |
448 | } | |
449 | ||
450 | /* | |
451 | * Writing to /proc/profile resets the counters | |
452 | * | |
453 | * Writing a 'profiling multiplier' value into it also re-sets the profiling | |
454 | * interrupt frequency, on architectures that support this. | |
455 | */ | |
456 | static ssize_t write_profile(struct file *file, const char __user *buf, | |
457 | size_t count, loff_t *ppos) | |
458 | { | |
459 | #ifdef CONFIG_SMP | |
460 | extern int setup_profiling_timer (unsigned int multiplier); | |
461 | ||
462 | if (count == sizeof(int)) { | |
463 | unsigned int multiplier; | |
464 | ||
465 | if (copy_from_user(&multiplier, buf, sizeof(int))) | |
466 | return -EFAULT; | |
467 | ||
468 | if (setup_profiling_timer(multiplier)) | |
469 | return -EINVAL; | |
470 | } | |
471 | #endif | |
472 | profile_discard_flip_buffers(); | |
473 | memset(prof_buffer, 0, prof_len * sizeof(atomic_t)); | |
474 | return count; | |
475 | } | |
476 | ||
477 | static struct file_operations proc_profile_operations = { | |
478 | .read = read_profile, | |
479 | .write = write_profile, | |
480 | }; | |
481 | ||
482 | #ifdef CONFIG_SMP | |
483 | static void __init profile_nop(void *unused) | |
484 | { | |
485 | } | |
486 | ||
487 | static int __init create_hash_tables(void) | |
488 | { | |
489 | int cpu; | |
490 | ||
491 | for_each_online_cpu(cpu) { | |
492 | int node = cpu_to_node(cpu); | |
493 | struct page *page; | |
494 | ||
495 | page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0); | |
496 | if (!page) | |
497 | goto out_cleanup; | |
498 | per_cpu(cpu_profile_hits, cpu)[1] | |
499 | = (struct profile_hit *)page_address(page); | |
500 | page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0); | |
501 | if (!page) | |
502 | goto out_cleanup; | |
503 | per_cpu(cpu_profile_hits, cpu)[0] | |
504 | = (struct profile_hit *)page_address(page); | |
505 | } | |
506 | return 0; | |
507 | out_cleanup: | |
508 | prof_on = 0; | |
d59dd462 | 509 | smp_mb(); |
1da177e4 LT |
510 | on_each_cpu(profile_nop, NULL, 0, 1); |
511 | for_each_online_cpu(cpu) { | |
512 | struct page *page; | |
513 | ||
514 | if (per_cpu(cpu_profile_hits, cpu)[0]) { | |
515 | page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]); | |
516 | per_cpu(cpu_profile_hits, cpu)[0] = NULL; | |
517 | __free_page(page); | |
518 | } | |
519 | if (per_cpu(cpu_profile_hits, cpu)[1]) { | |
520 | page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]); | |
521 | per_cpu(cpu_profile_hits, cpu)[1] = NULL; | |
522 | __free_page(page); | |
523 | } | |
524 | } | |
525 | return -1; | |
526 | } | |
527 | #else | |
528 | #define create_hash_tables() ({ 0; }) | |
529 | #endif | |
530 | ||
531 | static int __init create_proc_profile(void) | |
532 | { | |
533 | struct proc_dir_entry *entry; | |
534 | ||
535 | if (!prof_on) | |
536 | return 0; | |
537 | if (create_hash_tables()) | |
538 | return -1; | |
539 | if (!(entry = create_proc_entry("profile", S_IWUSR | S_IRUGO, NULL))) | |
540 | return 0; | |
541 | entry->proc_fops = &proc_profile_operations; | |
542 | entry->size = (1+prof_len) * sizeof(atomic_t); | |
543 | hotcpu_notifier(profile_cpu_callback, 0); | |
544 | return 0; | |
545 | } | |
546 | module_init(create_proc_profile); | |
547 | #endif /* CONFIG_PROC_FS */ |