Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/kernel/profile.c
Parent Directory | Revision Log
Revision 630 -
(show annotations)
(download)
Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 15264 byte(s)
Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 15264 byte(s)
Tag kernel26-2.6.12-alx-r9
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> |
26 | #include <asm/sections.h> |
27 | #include <asm/semaphore.h> |
28 | |
29 | struct profile_hit { |
30 | u32 pc, hits; |
31 | }; |
32 | #define PROFILE_GRPSHIFT 3 |
33 | #define PROFILE_GRPSZ (1 << PROFILE_GRPSHIFT) |
34 | #define NR_PROFILE_HIT (PAGE_SIZE/sizeof(struct profile_hit)) |
35 | #define NR_PROFILE_GRP (NR_PROFILE_HIT/PROFILE_GRPSZ) |
36 | |
37 | /* Oprofile timer tick hook */ |
38 | int (*timer_hook)(struct pt_regs *); |
39 | |
40 | static atomic_t *prof_buffer; |
41 | static unsigned long prof_len, prof_shift; |
42 | static int prof_on; |
43 | static cpumask_t prof_cpu_mask = CPU_MASK_ALL; |
44 | #ifdef CONFIG_SMP |
45 | static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits); |
46 | static DEFINE_PER_CPU(int, cpu_profile_flip); |
47 | static DECLARE_MUTEX(profile_flip_mutex); |
48 | #endif /* CONFIG_SMP */ |
49 | |
50 | static int __init profile_setup(char * str) |
51 | { |
52 | static char __initdata schedstr[] = "schedule"; |
53 | int par; |
54 | |
55 | if (!strncmp(str, schedstr, strlen(schedstr))) { |
56 | prof_on = SCHED_PROFILING; |
57 | if (str[strlen(schedstr)] == ',') |
58 | str += strlen(schedstr) + 1; |
59 | if (get_option(&str, &par)) |
60 | prof_shift = par; |
61 | printk(KERN_INFO |
62 | "kernel schedule profiling enabled (shift: %ld)\n", |
63 | prof_shift); |
64 | } else if (get_option(&str, &par)) { |
65 | prof_shift = par; |
66 | prof_on = CPU_PROFILING; |
67 | printk(KERN_INFO "kernel profiling enabled (shift: %ld)\n", |
68 | prof_shift); |
69 | } |
70 | return 1; |
71 | } |
72 | __setup("profile=", profile_setup); |
73 | |
74 | |
75 | void __init profile_init(void) |
76 | { |
77 | if (!prof_on) |
78 | return; |
79 | |
80 | /* only text is profiled */ |
81 | prof_len = (_etext - _stext) >> prof_shift; |
82 | prof_buffer = alloc_bootmem(prof_len*sizeof(atomic_t)); |
83 | } |
84 | |
85 | /* Profile event notifications */ |
86 | |
87 | #ifdef CONFIG_PROFILING |
88 | |
89 | static DECLARE_RWSEM(profile_rwsem); |
90 | static DEFINE_RWLOCK(handoff_lock); |
91 | static struct notifier_block * task_exit_notifier; |
92 | static struct notifier_block * task_free_notifier; |
93 | static struct notifier_block * munmap_notifier; |
94 | |
95 | void profile_task_exit(struct task_struct * task) |
96 | { |
97 | down_read(&profile_rwsem); |
98 | notifier_call_chain(&task_exit_notifier, 0, task); |
99 | up_read(&profile_rwsem); |
100 | } |
101 | |
102 | int profile_handoff_task(struct task_struct * task) |
103 | { |
104 | int ret; |
105 | read_lock(&handoff_lock); |
106 | ret = notifier_call_chain(&task_free_notifier, 0, task); |
107 | read_unlock(&handoff_lock); |
108 | return (ret == NOTIFY_OK) ? 1 : 0; |
109 | } |
110 | |
111 | void profile_munmap(unsigned long addr) |
112 | { |
113 | down_read(&profile_rwsem); |
114 | notifier_call_chain(&munmap_notifier, 0, (void *)addr); |
115 | up_read(&profile_rwsem); |
116 | } |
117 | |
118 | int task_handoff_register(struct notifier_block * n) |
119 | { |
120 | int err = -EINVAL; |
121 | |
122 | write_lock(&handoff_lock); |
123 | err = notifier_chain_register(&task_free_notifier, n); |
124 | write_unlock(&handoff_lock); |
125 | return err; |
126 | } |
127 | |
128 | int task_handoff_unregister(struct notifier_block * n) |
129 | { |
130 | int err = -EINVAL; |
131 | |
132 | write_lock(&handoff_lock); |
133 | err = notifier_chain_unregister(&task_free_notifier, n); |
134 | write_unlock(&handoff_lock); |
135 | return err; |
136 | } |
137 | |
138 | int profile_event_register(enum profile_type type, struct notifier_block * n) |
139 | { |
140 | int err = -EINVAL; |
141 | |
142 | down_write(&profile_rwsem); |
143 | |
144 | switch (type) { |
145 | case PROFILE_TASK_EXIT: |
146 | err = notifier_chain_register(&task_exit_notifier, n); |
147 | break; |
148 | case PROFILE_MUNMAP: |
149 | err = notifier_chain_register(&munmap_notifier, n); |
150 | break; |
151 | } |
152 | |
153 | up_write(&profile_rwsem); |
154 | |
155 | return err; |
156 | } |
157 | |
158 | |
159 | int profile_event_unregister(enum profile_type type, struct notifier_block * n) |
160 | { |
161 | int err = -EINVAL; |
162 | |
163 | down_write(&profile_rwsem); |
164 | |
165 | switch (type) { |
166 | case PROFILE_TASK_EXIT: |
167 | err = notifier_chain_unregister(&task_exit_notifier, n); |
168 | break; |
169 | case PROFILE_MUNMAP: |
170 | err = notifier_chain_unregister(&munmap_notifier, n); |
171 | break; |
172 | } |
173 | |
174 | up_write(&profile_rwsem); |
175 | return err; |
176 | } |
177 | |
178 | int register_timer_hook(int (*hook)(struct pt_regs *)) |
179 | { |
180 | if (timer_hook) |
181 | return -EBUSY; |
182 | timer_hook = hook; |
183 | return 0; |
184 | } |
185 | |
186 | void unregister_timer_hook(int (*hook)(struct pt_regs *)) |
187 | { |
188 | WARN_ON(hook != timer_hook); |
189 | timer_hook = NULL; |
190 | /* make sure all CPUs see the NULL hook */ |
191 | synchronize_sched(); /* Allow ongoing interrupts to complete. */ |
192 | } |
193 | |
194 | EXPORT_SYMBOL_GPL(register_timer_hook); |
195 | EXPORT_SYMBOL_GPL(unregister_timer_hook); |
196 | EXPORT_SYMBOL_GPL(task_handoff_register); |
197 | EXPORT_SYMBOL_GPL(task_handoff_unregister); |
198 | |
199 | #endif /* CONFIG_PROFILING */ |
200 | |
201 | EXPORT_SYMBOL_GPL(profile_event_register); |
202 | EXPORT_SYMBOL_GPL(profile_event_unregister); |
203 | |
204 | #ifdef CONFIG_SMP |
205 | /* |
206 | * Each cpu has a pair of open-addressed hashtables for pending |
207 | * profile hits. read_profile() IPI's all cpus to request them |
208 | * to flip buffers and flushes their contents to prof_buffer itself. |
209 | * Flip requests are serialized by the profile_flip_mutex. The sole |
210 | * use of having a second hashtable is for avoiding cacheline |
211 | * contention that would otherwise happen during flushes of pending |
212 | * profile hits required for the accuracy of reported profile hits |
213 | * and so resurrect the interrupt livelock issue. |
214 | * |
215 | * The open-addressed hashtables are indexed by profile buffer slot |
216 | * and hold the number of pending hits to that profile buffer slot on |
217 | * a cpu in an entry. When the hashtable overflows, all pending hits |
218 | * are accounted to their corresponding profile buffer slots with |
219 | * atomic_add() and the hashtable emptied. As numerous pending hits |
220 | * may be accounted to a profile buffer slot in a hashtable entry, |
221 | * this amortizes a number of atomic profile buffer increments likely |
222 | * to be far larger than the number of entries in the hashtable, |
223 | * particularly given that the number of distinct profile buffer |
224 | * positions to which hits are accounted during short intervals (e.g. |
225 | * several seconds) is usually very small. Exclusion from buffer |
226 | * flipping is provided by interrupt disablement (note that for |
227 | * SCHED_PROFILING profile_hit() may be called from process context). |
228 | * The hash function is meant to be lightweight as opposed to strong, |
229 | * and was vaguely inspired by ppc64 firmware-supported inverted |
230 | * pagetable hash functions, but uses a full hashtable full of finite |
231 | * collision chains, not just pairs of them. |
232 | * |
233 | * -- wli |
234 | */ |
235 | static void __profile_flip_buffers(void *unused) |
236 | { |
237 | int cpu = smp_processor_id(); |
238 | |
239 | per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu); |
240 | } |
241 | |
242 | static void profile_flip_buffers(void) |
243 | { |
244 | int i, j, cpu; |
245 | |
246 | down(&profile_flip_mutex); |
247 | j = per_cpu(cpu_profile_flip, get_cpu()); |
248 | put_cpu(); |
249 | on_each_cpu(__profile_flip_buffers, NULL, 0, 1); |
250 | for_each_online_cpu(cpu) { |
251 | struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j]; |
252 | for (i = 0; i < NR_PROFILE_HIT; ++i) { |
253 | if (!hits[i].hits) { |
254 | if (hits[i].pc) |
255 | hits[i].pc = 0; |
256 | continue; |
257 | } |
258 | atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]); |
259 | hits[i].hits = hits[i].pc = 0; |
260 | } |
261 | } |
262 | up(&profile_flip_mutex); |
263 | } |
264 | |
265 | static void profile_discard_flip_buffers(void) |
266 | { |
267 | int i, cpu; |
268 | |
269 | down(&profile_flip_mutex); |
270 | i = per_cpu(cpu_profile_flip, get_cpu()); |
271 | put_cpu(); |
272 | on_each_cpu(__profile_flip_buffers, NULL, 0, 1); |
273 | for_each_online_cpu(cpu) { |
274 | struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i]; |
275 | memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit)); |
276 | } |
277 | up(&profile_flip_mutex); |
278 | } |
279 | |
280 | void profile_hit(int type, void *__pc) |
281 | { |
282 | unsigned long primary, secondary, flags, pc = (unsigned long)__pc; |
283 | int i, j, cpu; |
284 | struct profile_hit *hits; |
285 | |
286 | if (prof_on != type || !prof_buffer) |
287 | return; |
288 | pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1); |
289 | i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT; |
290 | secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT; |
291 | cpu = get_cpu(); |
292 | hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)]; |
293 | if (!hits) { |
294 | put_cpu(); |
295 | return; |
296 | } |
297 | local_irq_save(flags); |
298 | do { |
299 | for (j = 0; j < PROFILE_GRPSZ; ++j) { |
300 | if (hits[i + j].pc == pc) { |
301 | hits[i + j].hits++; |
302 | goto out; |
303 | } else if (!hits[i + j].hits) { |
304 | hits[i + j].pc = pc; |
305 | hits[i + j].hits = 1; |
306 | goto out; |
307 | } |
308 | } |
309 | i = (i + secondary) & (NR_PROFILE_HIT - 1); |
310 | } while (i != primary); |
311 | atomic_inc(&prof_buffer[pc]); |
312 | for (i = 0; i < NR_PROFILE_HIT; ++i) { |
313 | atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]); |
314 | hits[i].pc = hits[i].hits = 0; |
315 | } |
316 | out: |
317 | local_irq_restore(flags); |
318 | put_cpu(); |
319 | } |
320 | |
321 | #ifdef CONFIG_HOTPLUG_CPU |
322 | static int __devinit profile_cpu_callback(struct notifier_block *info, |
323 | unsigned long action, void *__cpu) |
324 | { |
325 | int node, cpu = (unsigned long)__cpu; |
326 | struct page *page; |
327 | |
328 | switch (action) { |
329 | case CPU_UP_PREPARE: |
330 | node = cpu_to_node(cpu); |
331 | per_cpu(cpu_profile_flip, cpu) = 0; |
332 | if (!per_cpu(cpu_profile_hits, cpu)[1]) { |
333 | page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0); |
334 | if (!page) |
335 | return NOTIFY_BAD; |
336 | per_cpu(cpu_profile_hits, cpu)[1] = page_address(page); |
337 | } |
338 | if (!per_cpu(cpu_profile_hits, cpu)[0]) { |
339 | page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0); |
340 | if (!page) |
341 | goto out_free; |
342 | per_cpu(cpu_profile_hits, cpu)[0] = page_address(page); |
343 | } |
344 | break; |
345 | out_free: |
346 | page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]); |
347 | per_cpu(cpu_profile_hits, cpu)[1] = NULL; |
348 | __free_page(page); |
349 | return NOTIFY_BAD; |
350 | case CPU_ONLINE: |
351 | cpu_set(cpu, prof_cpu_mask); |
352 | break; |
353 | case CPU_UP_CANCELED: |
354 | case CPU_DEAD: |
355 | cpu_clear(cpu, prof_cpu_mask); |
356 | if (per_cpu(cpu_profile_hits, cpu)[0]) { |
357 | page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]); |
358 | per_cpu(cpu_profile_hits, cpu)[0] = NULL; |
359 | __free_page(page); |
360 | } |
361 | if (per_cpu(cpu_profile_hits, cpu)[1]) { |
362 | page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]); |
363 | per_cpu(cpu_profile_hits, cpu)[1] = NULL; |
364 | __free_page(page); |
365 | } |
366 | break; |
367 | } |
368 | return NOTIFY_OK; |
369 | } |
370 | #endif /* CONFIG_HOTPLUG_CPU */ |
371 | #else /* !CONFIG_SMP */ |
372 | #define profile_flip_buffers() do { } while (0) |
373 | #define profile_discard_flip_buffers() do { } while (0) |
374 | |
375 | void profile_hit(int type, void *__pc) |
376 | { |
377 | unsigned long pc; |
378 | |
379 | if (prof_on != type || !prof_buffer) |
380 | return; |
381 | pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift; |
382 | atomic_inc(&prof_buffer[min(pc, prof_len - 1)]); |
383 | } |
384 | #endif /* !CONFIG_SMP */ |
385 | |
386 | void profile_tick(int type, struct pt_regs *regs) |
387 | { |
388 | if (type == CPU_PROFILING && timer_hook) |
389 | timer_hook(regs); |
390 | if (!user_mode(regs) && cpu_isset(smp_processor_id(), prof_cpu_mask)) |
391 | profile_hit(type, (void *)profile_pc(regs)); |
392 | } |
393 | |
394 | #ifdef CONFIG_PROC_FS |
395 | #include <linux/proc_fs.h> |
396 | #include <asm/uaccess.h> |
397 | #include <asm/ptrace.h> |
398 | |
399 | static int prof_cpu_mask_read_proc (char *page, char **start, off_t off, |
400 | int count, int *eof, void *data) |
401 | { |
402 | int len = cpumask_scnprintf(page, count, *(cpumask_t *)data); |
403 | if (count - len < 2) |
404 | return -EINVAL; |
405 | len += sprintf(page + len, "\n"); |
406 | return len; |
407 | } |
408 | |
409 | static int prof_cpu_mask_write_proc (struct file *file, const char __user *buffer, |
410 | unsigned long count, void *data) |
411 | { |
412 | cpumask_t *mask = (cpumask_t *)data; |
413 | unsigned long full_count = count, err; |
414 | cpumask_t new_value; |
415 | |
416 | err = cpumask_parse(buffer, count, new_value); |
417 | if (err) |
418 | return err; |
419 | |
420 | *mask = new_value; |
421 | return full_count; |
422 | } |
423 | |
424 | void create_prof_cpu_mask(struct proc_dir_entry *root_irq_dir) |
425 | { |
426 | struct proc_dir_entry *entry; |
427 | |
428 | /* create /proc/irq/prof_cpu_mask */ |
429 | if (!(entry = create_proc_entry("prof_cpu_mask", 0600, root_irq_dir))) |
430 | return; |
431 | entry->nlink = 1; |
432 | entry->data = (void *)&prof_cpu_mask; |
433 | entry->read_proc = prof_cpu_mask_read_proc; |
434 | entry->write_proc = prof_cpu_mask_write_proc; |
435 | } |
436 | |
437 | /* |
438 | * This function accesses profiling information. The returned data is |
439 | * binary: the sampling step and the actual contents of the profile |
440 | * buffer. Use of the program readprofile is recommended in order to |
441 | * get meaningful info out of these data. |
442 | */ |
443 | static ssize_t |
444 | read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos) |
445 | { |
446 | unsigned long p = *ppos; |
447 | ssize_t read; |
448 | char * pnt; |
449 | unsigned int sample_step = 1 << prof_shift; |
450 | |
451 | profile_flip_buffers(); |
452 | if (p >= (prof_len+1)*sizeof(unsigned int)) |
453 | return 0; |
454 | if (count > (prof_len+1)*sizeof(unsigned int) - p) |
455 | count = (prof_len+1)*sizeof(unsigned int) - p; |
456 | read = 0; |
457 | |
458 | while (p < sizeof(unsigned int) && count > 0) { |
459 | put_user(*((char *)(&sample_step)+p),buf); |
460 | buf++; p++; count--; read++; |
461 | } |
462 | pnt = (char *)prof_buffer + p - sizeof(atomic_t); |
463 | if (copy_to_user(buf,(void *)pnt,count)) |
464 | return -EFAULT; |
465 | read += count; |
466 | *ppos += read; |
467 | return read; |
468 | } |
469 | |
470 | /* |
471 | * Writing to /proc/profile resets the counters |
472 | * |
473 | * Writing a 'profiling multiplier' value into it also re-sets the profiling |
474 | * interrupt frequency, on architectures that support this. |
475 | */ |
476 | static ssize_t write_profile(struct file *file, const char __user *buf, |
477 | size_t count, loff_t *ppos) |
478 | { |
479 | #ifdef CONFIG_SMP |
480 | extern int setup_profiling_timer (unsigned int multiplier); |
481 | |
482 | if (count == sizeof(int)) { |
483 | unsigned int multiplier; |
484 | |
485 | if (copy_from_user(&multiplier, buf, sizeof(int))) |
486 | return -EFAULT; |
487 | |
488 | if (setup_profiling_timer(multiplier)) |
489 | return -EINVAL; |
490 | } |
491 | #endif |
492 | profile_discard_flip_buffers(); |
493 | memset(prof_buffer, 0, prof_len * sizeof(atomic_t)); |
494 | return count; |
495 | } |
496 | |
497 | static struct file_operations proc_profile_operations = { |
498 | .read = read_profile, |
499 | .write = write_profile, |
500 | }; |
501 | |
502 | #ifdef CONFIG_SMP |
503 | static void __init profile_nop(void *unused) |
504 | { |
505 | } |
506 | |
507 | static int __init create_hash_tables(void) |
508 | { |
509 | int cpu; |
510 | |
511 | for_each_online_cpu(cpu) { |
512 | int node = cpu_to_node(cpu); |
513 | struct page *page; |
514 | |
515 | page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0); |
516 | if (!page) |
517 | goto out_cleanup; |
518 | per_cpu(cpu_profile_hits, cpu)[1] |
519 | = (struct profile_hit *)page_address(page); |
520 | page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0); |
521 | if (!page) |
522 | goto out_cleanup; |
523 | per_cpu(cpu_profile_hits, cpu)[0] |
524 | = (struct profile_hit *)page_address(page); |
525 | } |
526 | return 0; |
527 | out_cleanup: |
528 | prof_on = 0; |
529 | smp_mb(); |
530 | on_each_cpu(profile_nop, NULL, 0, 1); |
531 | for_each_online_cpu(cpu) { |
532 | struct page *page; |
533 | |
534 | if (per_cpu(cpu_profile_hits, cpu)[0]) { |
535 | page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]); |
536 | per_cpu(cpu_profile_hits, cpu)[0] = NULL; |
537 | __free_page(page); |
538 | } |
539 | if (per_cpu(cpu_profile_hits, cpu)[1]) { |
540 | page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]); |
541 | per_cpu(cpu_profile_hits, cpu)[1] = NULL; |
542 | __free_page(page); |
543 | } |
544 | } |
545 | return -1; |
546 | } |
547 | #else |
548 | #define create_hash_tables() ({ 0; }) |
549 | #endif |
550 | |
551 | static int __init create_proc_profile(void) |
552 | { |
553 | struct proc_dir_entry *entry; |
554 | |
555 | if (!prof_on) |
556 | return 0; |
557 | if (create_hash_tables()) |
558 | return -1; |
559 | if (!(entry = create_proc_entry("profile", S_IWUSR | S_IRUGO, NULL))) |
560 | return 0; |
561 | entry->proc_fops = &proc_profile_operations; |
562 | entry->size = (1+prof_len) * sizeof(atomic_t); |
563 | hotcpu_notifier(profile_cpu_callback, 0); |
564 | return 0; |
565 | } |
566 | module_init(create_proc_profile); |
567 | #endif /* CONFIG_PROC_FS */ |