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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /kernel/profile.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'kernel/profile.c')
-rw-r--r--kernel/profile.c563
1 files changed, 563 insertions, 0 deletions
diff --git a/kernel/profile.c b/kernel/profile.c
new file mode 100644
index 000000000000..a38fa70075fe
--- /dev/null
+++ b/kernel/profile.c
@@ -0,0 +1,563 @@
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
29struct 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 */
38int (*timer_hook)(struct pt_regs *);
39
40static atomic_t *prof_buffer;
41static unsigned long prof_len, prof_shift;
42static int prof_on;
43static cpumask_t prof_cpu_mask = CPU_MASK_ALL;
44#ifdef CONFIG_SMP
45static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
46static DEFINE_PER_CPU(int, cpu_profile_flip);
47static DECLARE_MUTEX(profile_flip_mutex);
48#endif /* CONFIG_SMP */
49
50static int __init profile_setup(char * str)
51{
52 int par;
53
54 if (!strncmp(str, "schedule", 8)) {
55 prof_on = SCHED_PROFILING;
56 printk(KERN_INFO "kernel schedule profiling enabled\n");
57 if (str[7] == ',')
58 str += 8;
59 }
60 if (get_option(&str,&par)) {
61 prof_shift = par;
62 prof_on = CPU_PROFILING;
63 printk(KERN_INFO "kernel profiling enabled (shift: %ld)\n",
64 prof_shift);
65 }
66 return 1;
67}
68__setup("profile=", profile_setup);
69
70
71void __init profile_init(void)
72{
73 if (!prof_on)
74 return;
75
76 /* only text is profiled */
77 prof_len = (_etext - _stext) >> prof_shift;
78 prof_buffer = alloc_bootmem(prof_len*sizeof(atomic_t));
79}
80
81/* Profile event notifications */
82
83#ifdef CONFIG_PROFILING
84
85static DECLARE_RWSEM(profile_rwsem);
86static DEFINE_RWLOCK(handoff_lock);
87static struct notifier_block * task_exit_notifier;
88static struct notifier_block * task_free_notifier;
89static struct notifier_block * munmap_notifier;
90
91void profile_task_exit(struct task_struct * task)
92{
93 down_read(&profile_rwsem);
94 notifier_call_chain(&task_exit_notifier, 0, task);
95 up_read(&profile_rwsem);
96}
97
98int profile_handoff_task(struct task_struct * task)
99{
100 int ret;
101 read_lock(&handoff_lock);
102 ret = notifier_call_chain(&task_free_notifier, 0, task);
103 read_unlock(&handoff_lock);
104 return (ret == NOTIFY_OK) ? 1 : 0;
105}
106
107void profile_munmap(unsigned long addr)
108{
109 down_read(&profile_rwsem);
110 notifier_call_chain(&munmap_notifier, 0, (void *)addr);
111 up_read(&profile_rwsem);
112}
113
114int task_handoff_register(struct notifier_block * n)
115{
116 int err = -EINVAL;
117
118 write_lock(&handoff_lock);
119 err = notifier_chain_register(&task_free_notifier, n);
120 write_unlock(&handoff_lock);
121 return err;
122}
123
124int task_handoff_unregister(struct notifier_block * n)
125{
126 int err = -EINVAL;
127
128 write_lock(&handoff_lock);
129 err = notifier_chain_unregister(&task_free_notifier, n);
130 write_unlock(&handoff_lock);
131 return err;
132}
133
134int profile_event_register(enum profile_type type, struct notifier_block * n)
135{
136 int err = -EINVAL;
137
138 down_write(&profile_rwsem);
139
140 switch (type) {
141 case PROFILE_TASK_EXIT:
142 err = notifier_chain_register(&task_exit_notifier, n);
143 break;
144 case PROFILE_MUNMAP:
145 err = notifier_chain_register(&munmap_notifier, n);
146 break;
147 }
148
149 up_write(&profile_rwsem);
150
151 return err;
152}
153
154
155int profile_event_unregister(enum profile_type type, struct notifier_block * n)
156{
157 int err = -EINVAL;
158
159 down_write(&profile_rwsem);
160
161 switch (type) {
162 case PROFILE_TASK_EXIT:
163 err = notifier_chain_unregister(&task_exit_notifier, n);
164 break;
165 case PROFILE_MUNMAP:
166 err = notifier_chain_unregister(&munmap_notifier, n);
167 break;
168 }
169
170 up_write(&profile_rwsem);
171 return err;
172}
173
174int register_timer_hook(int (*hook)(struct pt_regs *))
175{
176 if (timer_hook)
177 return -EBUSY;
178 timer_hook = hook;
179 return 0;
180}
181
182void unregister_timer_hook(int (*hook)(struct pt_regs *))
183{
184 WARN_ON(hook != timer_hook);
185 timer_hook = NULL;
186 /* make sure all CPUs see the NULL hook */
187 synchronize_kernel();
188}
189
190EXPORT_SYMBOL_GPL(register_timer_hook);
191EXPORT_SYMBOL_GPL(unregister_timer_hook);
192EXPORT_SYMBOL_GPL(task_handoff_register);
193EXPORT_SYMBOL_GPL(task_handoff_unregister);
194
195#endif /* CONFIG_PROFILING */
196
197EXPORT_SYMBOL_GPL(profile_event_register);
198EXPORT_SYMBOL_GPL(profile_event_unregister);
199
200#ifdef CONFIG_SMP
201/*
202 * Each cpu has a pair of open-addressed hashtables for pending
203 * profile hits. read_profile() IPI's all cpus to request them
204 * to flip buffers and flushes their contents to prof_buffer itself.
205 * Flip requests are serialized by the profile_flip_mutex. The sole
206 * use of having a second hashtable is for avoiding cacheline
207 * contention that would otherwise happen during flushes of pending
208 * profile hits required for the accuracy of reported profile hits
209 * and so resurrect the interrupt livelock issue.
210 *
211 * The open-addressed hashtables are indexed by profile buffer slot
212 * and hold the number of pending hits to that profile buffer slot on
213 * a cpu in an entry. When the hashtable overflows, all pending hits
214 * are accounted to their corresponding profile buffer slots with
215 * atomic_add() and the hashtable emptied. As numerous pending hits
216 * may be accounted to a profile buffer slot in a hashtable entry,
217 * this amortizes a number of atomic profile buffer increments likely
218 * to be far larger than the number of entries in the hashtable,
219 * particularly given that the number of distinct profile buffer
220 * positions to which hits are accounted during short intervals (e.g.
221 * several seconds) is usually very small. Exclusion from buffer
222 * flipping is provided by interrupt disablement (note that for
223 * SCHED_PROFILING profile_hit() may be called from process context).
224 * The hash function is meant to be lightweight as opposed to strong,
225 * and was vaguely inspired by ppc64 firmware-supported inverted
226 * pagetable hash functions, but uses a full hashtable full of finite
227 * collision chains, not just pairs of them.
228 *
229 * -- wli
230 */
231static void __profile_flip_buffers(void *unused)
232{
233 int cpu = smp_processor_id();
234
235 per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
236}
237
238static void profile_flip_buffers(void)
239{
240 int i, j, cpu;
241
242 down(&profile_flip_mutex);
243 j = per_cpu(cpu_profile_flip, get_cpu());
244 put_cpu();
245 on_each_cpu(__profile_flip_buffers, NULL, 0, 1);
246 for_each_online_cpu(cpu) {
247 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
248 for (i = 0; i < NR_PROFILE_HIT; ++i) {
249 if (!hits[i].hits) {
250 if (hits[i].pc)
251 hits[i].pc = 0;
252 continue;
253 }
254 atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
255 hits[i].hits = hits[i].pc = 0;
256 }
257 }
258 up(&profile_flip_mutex);
259}
260
261static void profile_discard_flip_buffers(void)
262{
263 int i, cpu;
264
265 down(&profile_flip_mutex);
266 i = per_cpu(cpu_profile_flip, get_cpu());
267 put_cpu();
268 on_each_cpu(__profile_flip_buffers, NULL, 0, 1);
269 for_each_online_cpu(cpu) {
270 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
271 memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
272 }
273 up(&profile_flip_mutex);
274}
275
276void profile_hit(int type, void *__pc)
277{
278 unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
279 int i, j, cpu;
280 struct profile_hit *hits;
281
282 if (prof_on != type || !prof_buffer)
283 return;
284 pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
285 i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
286 secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
287 cpu = get_cpu();
288 hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
289 if (!hits) {
290 put_cpu();
291 return;
292 }
293 local_irq_save(flags);
294 do {
295 for (j = 0; j < PROFILE_GRPSZ; ++j) {
296 if (hits[i + j].pc == pc) {
297 hits[i + j].hits++;
298 goto out;
299 } else if (!hits[i + j].hits) {
300 hits[i + j].pc = pc;
301 hits[i + j].hits = 1;
302 goto out;
303 }
304 }
305 i = (i + secondary) & (NR_PROFILE_HIT - 1);
306 } while (i != primary);
307 atomic_inc(&prof_buffer[pc]);
308 for (i = 0; i < NR_PROFILE_HIT; ++i) {
309 atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
310 hits[i].pc = hits[i].hits = 0;
311 }
312out:
313 local_irq_restore(flags);
314 put_cpu();
315}
316
317#ifdef CONFIG_HOTPLUG_CPU
318static int __devinit profile_cpu_callback(struct notifier_block *info,
319 unsigned long action, void *__cpu)
320{
321 int node, cpu = (unsigned long)__cpu;
322 struct page *page;
323
324 switch (action) {
325 case CPU_UP_PREPARE:
326 node = cpu_to_node(cpu);
327 per_cpu(cpu_profile_flip, cpu) = 0;
328 if (!per_cpu(cpu_profile_hits, cpu)[1]) {
329 page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
330 if (!page)
331 return NOTIFY_BAD;
332 per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
333 }
334 if (!per_cpu(cpu_profile_hits, cpu)[0]) {
335 page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
336 if (!page)
337 goto out_free;
338 per_cpu(cpu_profile_hits, cpu)[0] = page_address(page);
339 }
340 break;
341 out_free:
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 return NOTIFY_BAD;
346 case CPU_ONLINE:
347 cpu_set(cpu, prof_cpu_mask);
348 break;
349 case CPU_UP_CANCELED:
350 case CPU_DEAD:
351 cpu_clear(cpu, prof_cpu_mask);
352 if (per_cpu(cpu_profile_hits, cpu)[0]) {
353 page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
354 per_cpu(cpu_profile_hits, cpu)[0] = NULL;
355 __free_page(page);
356 }
357 if (per_cpu(cpu_profile_hits, cpu)[1]) {
358 page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
359 per_cpu(cpu_profile_hits, cpu)[1] = NULL;
360 __free_page(page);
361 }
362 break;
363 }
364 return NOTIFY_OK;
365}
366#endif /* CONFIG_HOTPLUG_CPU */
367#else /* !CONFIG_SMP */
368#define profile_flip_buffers() do { } while (0)
369#define profile_discard_flip_buffers() do { } while (0)
370
371void profile_hit(int type, void *__pc)
372{
373 unsigned long pc;
374
375 if (prof_on != type || !prof_buffer)
376 return;
377 pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
378 atomic_inc(&prof_buffer[min(pc, prof_len - 1)]);
379}
380#endif /* !CONFIG_SMP */
381
382void profile_tick(int type, struct pt_regs *regs)
383{
384 if (type == CPU_PROFILING && timer_hook)
385 timer_hook(regs);
386 if (!user_mode(regs) && cpu_isset(smp_processor_id(), prof_cpu_mask))
387 profile_hit(type, (void *)profile_pc(regs));
388}
389
390#ifdef CONFIG_PROC_FS
391#include <linux/proc_fs.h>
392#include <asm/uaccess.h>
393#include <asm/ptrace.h>
394
395static int prof_cpu_mask_read_proc (char *page, char **start, off_t off,
396 int count, int *eof, void *data)
397{
398 int len = cpumask_scnprintf(page, count, *(cpumask_t *)data);
399 if (count - len < 2)
400 return -EINVAL;
401 len += sprintf(page + len, "\n");
402 return len;
403}
404
405static int prof_cpu_mask_write_proc (struct file *file, const char __user *buffer,
406 unsigned long count, void *data)
407{
408 cpumask_t *mask = (cpumask_t *)data;
409 unsigned long full_count = count, err;
410 cpumask_t new_value;
411
412 err = cpumask_parse(buffer, count, new_value);
413 if (err)
414 return err;
415
416 *mask = new_value;
417 return full_count;
418}
419
420void create_prof_cpu_mask(struct proc_dir_entry *root_irq_dir)
421{
422 struct proc_dir_entry *entry;
423
424 /* create /proc/irq/prof_cpu_mask */
425 if (!(entry = create_proc_entry("prof_cpu_mask", 0600, root_irq_dir)))
426 return;
427 entry->nlink = 1;
428 entry->data = (void *)&prof_cpu_mask;
429 entry->read_proc = prof_cpu_mask_read_proc;
430 entry->write_proc = prof_cpu_mask_write_proc;
431}
432
433/*
434 * This function accesses profiling information. The returned data is
435 * binary: the sampling step and the actual contents of the profile
436 * buffer. Use of the program readprofile is recommended in order to
437 * get meaningful info out of these data.
438 */
439static ssize_t
440read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
441{
442 unsigned long p = *ppos;
443 ssize_t read;
444 char * pnt;
445 unsigned int sample_step = 1 << prof_shift;
446
447 profile_flip_buffers();
448 if (p >= (prof_len+1)*sizeof(unsigned int))
449 return 0;
450 if (count > (prof_len+1)*sizeof(unsigned int) - p)
451 count = (prof_len+1)*sizeof(unsigned int) - p;
452 read = 0;
453
454 while (p < sizeof(unsigned int) && count > 0) {
455 put_user(*((char *)(&sample_step)+p),buf);
456 buf++; p++; count--; read++;
457 }
458 pnt = (char *)prof_buffer + p - sizeof(atomic_t);
459 if (copy_to_user(buf,(void *)pnt,count))
460 return -EFAULT;
461 read += count;
462 *ppos += read;
463 return read;
464}
465
466/*
467 * Writing to /proc/profile resets the counters
468 *
469 * Writing a 'profiling multiplier' value into it also re-sets the profiling
470 * interrupt frequency, on architectures that support this.
471 */
472static ssize_t write_profile(struct file *file, const char __user *buf,
473 size_t count, loff_t *ppos)
474{
475#ifdef CONFIG_SMP
476 extern int setup_profiling_timer (unsigned int multiplier);
477
478 if (count == sizeof(int)) {
479 unsigned int multiplier;
480
481 if (copy_from_user(&multiplier, buf, sizeof(int)))
482 return -EFAULT;
483
484 if (setup_profiling_timer(multiplier))
485 return -EINVAL;
486 }
487#endif
488 profile_discard_flip_buffers();
489 memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
490 return count;
491}
492
493static struct file_operations proc_profile_operations = {
494 .read = read_profile,
495 .write = write_profile,
496};
497
498#ifdef CONFIG_SMP
499static void __init profile_nop(void *unused)
500{
501}
502
503static int __init create_hash_tables(void)
504{
505 int cpu;
506
507 for_each_online_cpu(cpu) {
508 int node = cpu_to_node(cpu);
509 struct page *page;
510
511 page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
512 if (!page)
513 goto out_cleanup;
514 per_cpu(cpu_profile_hits, cpu)[1]
515 = (struct profile_hit *)page_address(page);
516 page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
517 if (!page)
518 goto out_cleanup;
519 per_cpu(cpu_profile_hits, cpu)[0]
520 = (struct profile_hit *)page_address(page);
521 }
522 return 0;
523out_cleanup:
524 prof_on = 0;
525 mb();
526 on_each_cpu(profile_nop, NULL, 0, 1);
527 for_each_online_cpu(cpu) {
528 struct page *page;
529
530 if (per_cpu(cpu_profile_hits, cpu)[0]) {
531 page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
532 per_cpu(cpu_profile_hits, cpu)[0] = NULL;
533 __free_page(page);
534 }
535 if (per_cpu(cpu_profile_hits, cpu)[1]) {
536 page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
537 per_cpu(cpu_profile_hits, cpu)[1] = NULL;
538 __free_page(page);
539 }
540 }
541 return -1;
542}
543#else
544#define create_hash_tables() ({ 0; })
545#endif
546
547static int __init create_proc_profile(void)
548{
549 struct proc_dir_entry *entry;
550
551 if (!prof_on)
552 return 0;
553 if (create_hash_tables())
554 return -1;
555 if (!(entry = create_proc_entry("profile", S_IWUSR | S_IRUGO, NULL)))
556 return 0;
557 entry->proc_fops = &proc_profile_operations;
558 entry->size = (1+prof_len) * sizeof(atomic_t);
559 hotcpu_notifier(profile_cpu_callback, 0);
560 return 0;
561}
562module_init(create_proc_profile);
563#endif /* CONFIG_PROC_FS */