FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_prof.c
1 /*-
2 * Copyright (c) 1982, 1986, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)subr_prof.c 8.3 (Berkeley) 9/23/93
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/sysproto.h>
38 #include <sys/kernel.h>
39 #include <sys/lock.h>
40 #include <sys/mutex.h>
41 #include <sys/proc.h>
42 #include <sys/resourcevar.h>
43 #include <sys/sysctl.h>
44
45 #include <machine/cpu.h>
46
47 #ifdef GPROF
48 #include <sys/malloc.h>
49 #include <sys/gmon.h>
50 #undef MCOUNT
51
52 static MALLOC_DEFINE(M_GPROF, "gprof", "kernel profiling buffer");
53
54 static void kmstartup(void *);
55 SYSINIT(kmem, SI_SUB_KPROF, SI_ORDER_FIRST, kmstartup, NULL);
56
57 struct gmonparam _gmonparam = { GMON_PROF_OFF };
58
59 #ifdef GUPROF
60 void
61 nullfunc_loop_profiled()
62 {
63 int i;
64
65 for (i = 0; i < CALIB_SCALE; i++)
66 nullfunc_profiled();
67 }
68
69 #define nullfunc_loop_profiled_end nullfunc_profiled /* XXX */
70
71 void
72 nullfunc_profiled()
73 {
74 }
75 #endif /* GUPROF */
76
77 /*
78 * Update the histograms to support extending the text region arbitrarily.
79 * This is done slightly naively (no sparse regions), so will waste slight
80 * amounts of memory, but will overall work nicely enough to allow profiling
81 * of KLDs.
82 */
83 void
84 kmupetext(uintfptr_t nhighpc)
85 {
86 struct gmonparam np; /* slightly large */
87 struct gmonparam *p = &_gmonparam;
88 char *cp;
89
90 GIANT_REQUIRED;
91 bcopy(p, &np, sizeof(*p));
92 np.highpc = ROUNDUP(nhighpc, HISTFRACTION * sizeof(HISTCOUNTER));
93 if (np.highpc <= p->highpc)
94 return;
95 np.textsize = np.highpc - p->lowpc;
96 np.kcountsize = np.textsize / HISTFRACTION;
97 np.hashfraction = HASHFRACTION;
98 np.fromssize = np.textsize / HASHFRACTION;
99 np.tolimit = np.textsize * ARCDENSITY / 100;
100 if (np.tolimit < MINARCS)
101 np.tolimit = MINARCS;
102 else if (np.tolimit > MAXARCS)
103 np.tolimit = MAXARCS;
104 np.tossize = np.tolimit * sizeof(struct tostruct);
105 cp = malloc(np.kcountsize + np.fromssize + np.tossize,
106 M_GPROF, M_WAITOK);
107 /*
108 * Check for something else extending highpc while we slept.
109 */
110 if (np.highpc <= p->highpc) {
111 free(cp, M_GPROF);
112 return;
113 }
114 np.tos = (struct tostruct *)cp;
115 cp += np.tossize;
116 np.kcount = (HISTCOUNTER *)cp;
117 cp += np.kcountsize;
118 np.froms = (u_short *)cp;
119 #ifdef GUPROF
120 /* Reinitialize pointers to overhead counters. */
121 np.cputime_count = &KCOUNT(&np, PC_TO_I(&np, cputime));
122 np.mcount_count = &KCOUNT(&np, PC_TO_I(&np, mcount));
123 np.mexitcount_count = &KCOUNT(&np, PC_TO_I(&np, mexitcount));
124 #endif
125 critical_enter();
126 bcopy(p->tos, np.tos, p->tossize);
127 bzero((char *)np.tos + p->tossize, np.tossize - p->tossize);
128 bcopy(p->kcount, np.kcount, p->kcountsize);
129 bzero((char *)np.kcount + p->kcountsize, np.kcountsize -
130 p->kcountsize);
131 bcopy(p->froms, np.froms, p->fromssize);
132 bzero((char *)np.froms + p->fromssize, np.fromssize - p->fromssize);
133 cp = (char *)p->tos;
134 bcopy(&np, p, sizeof(*p));
135 critical_exit();
136 free(cp, M_GPROF);
137 }
138
139 static void
140 kmstartup(dummy)
141 void *dummy;
142 {
143 char *cp;
144 struct gmonparam *p = &_gmonparam;
145 #ifdef GUPROF
146 int cputime_overhead;
147 int empty_loop_time;
148 int i;
149 int mcount_overhead;
150 int mexitcount_overhead;
151 int nullfunc_loop_overhead;
152 int nullfunc_loop_profiled_time;
153 uintfptr_t tmp_addr;
154 #endif
155
156 /*
157 * Round lowpc and highpc to multiples of the density we're using
158 * so the rest of the scaling (here and in gprof) stays in ints.
159 */
160 p->lowpc = ROUNDDOWN((u_long)btext, HISTFRACTION * sizeof(HISTCOUNTER));
161 p->highpc = ROUNDUP((u_long)etext, HISTFRACTION * sizeof(HISTCOUNTER));
162 p->textsize = p->highpc - p->lowpc;
163 printf("Profiling kernel, textsize=%lu [%jx..%jx]\n",
164 p->textsize, (uintmax_t)p->lowpc, (uintmax_t)p->highpc);
165 p->kcountsize = p->textsize / HISTFRACTION;
166 p->hashfraction = HASHFRACTION;
167 p->fromssize = p->textsize / HASHFRACTION;
168 p->tolimit = p->textsize * ARCDENSITY / 100;
169 if (p->tolimit < MINARCS)
170 p->tolimit = MINARCS;
171 else if (p->tolimit > MAXARCS)
172 p->tolimit = MAXARCS;
173 p->tossize = p->tolimit * sizeof(struct tostruct);
174 cp = (char *)malloc(p->kcountsize + p->fromssize + p->tossize,
175 M_GPROF, M_WAITOK | M_ZERO);
176 p->tos = (struct tostruct *)cp;
177 cp += p->tossize;
178 p->kcount = (HISTCOUNTER *)cp;
179 cp += p->kcountsize;
180 p->froms = (u_short *)cp;
181 p->histcounter_type = FUNCTION_ALIGNMENT / HISTFRACTION * NBBY;
182
183 #ifdef GUPROF
184 /* Signed counters. */
185 p->histcounter_type = -p->histcounter_type;
186
187 /* Initialize pointers to overhead counters. */
188 p->cputime_count = &KCOUNT(p, PC_TO_I(p, cputime));
189 p->mcount_count = &KCOUNT(p, PC_TO_I(p, mcount));
190 p->mexitcount_count = &KCOUNT(p, PC_TO_I(p, mexitcount));
191
192 /*
193 * Disable interrupts to avoid interference while we calibrate
194 * things.
195 */
196 critical_enter();
197
198 /*
199 * Determine overheads.
200 * XXX this needs to be repeated for each useful timer/counter.
201 */
202 cputime_overhead = 0;
203 startguprof(p);
204 for (i = 0; i < CALIB_SCALE; i++)
205 cputime_overhead += cputime();
206
207 empty_loop();
208 startguprof(p);
209 empty_loop();
210 empty_loop_time = cputime();
211
212 nullfunc_loop_profiled();
213
214 /*
215 * Start profiling. There won't be any normal function calls since
216 * interrupts are disabled, but we will call the profiling routines
217 * directly to determine their overheads.
218 */
219 p->state = GMON_PROF_HIRES;
220
221 startguprof(p);
222 nullfunc_loop_profiled();
223
224 startguprof(p);
225 for (i = 0; i < CALIB_SCALE; i++)
226 MCOUNT_OVERHEAD(sys_profil);
227 mcount_overhead = KCOUNT(p, PC_TO_I(p, sys_profil));
228
229 startguprof(p);
230 for (i = 0; i < CALIB_SCALE; i++)
231 MEXITCOUNT_OVERHEAD();
232 MEXITCOUNT_OVERHEAD_GETLABEL(tmp_addr);
233 mexitcount_overhead = KCOUNT(p, PC_TO_I(p, tmp_addr));
234
235 p->state = GMON_PROF_OFF;
236 stopguprof(p);
237
238 critical_exit();
239
240 nullfunc_loop_profiled_time = 0;
241 for (tmp_addr = (uintfptr_t)nullfunc_loop_profiled;
242 tmp_addr < (uintfptr_t)nullfunc_loop_profiled_end;
243 tmp_addr += HISTFRACTION * sizeof(HISTCOUNTER))
244 nullfunc_loop_profiled_time += KCOUNT(p, PC_TO_I(p, tmp_addr));
245 #define CALIB_DOSCALE(count) (((count) + CALIB_SCALE / 3) / CALIB_SCALE)
246 #define c2n(count, freq) ((int)((count) * 1000000000LL / freq))
247 printf("cputime %d, empty_loop %d, nullfunc_loop_profiled %d, mcount %d, mexitcount %d\n",
248 CALIB_DOSCALE(c2n(cputime_overhead, p->profrate)),
249 CALIB_DOSCALE(c2n(empty_loop_time, p->profrate)),
250 CALIB_DOSCALE(c2n(nullfunc_loop_profiled_time, p->profrate)),
251 CALIB_DOSCALE(c2n(mcount_overhead, p->profrate)),
252 CALIB_DOSCALE(c2n(mexitcount_overhead, p->profrate)));
253 cputime_overhead -= empty_loop_time;
254 mcount_overhead -= empty_loop_time;
255 mexitcount_overhead -= empty_loop_time;
256
257 /*-
258 * Profiling overheads are determined by the times between the
259 * following events:
260 * MC1: mcount() is called
261 * MC2: cputime() (called from mcount()) latches the timer
262 * MC3: mcount() completes
263 * ME1: mexitcount() is called
264 * ME2: cputime() (called from mexitcount()) latches the timer
265 * ME3: mexitcount() completes.
266 * The times between the events vary slightly depending on instruction
267 * combination and cache misses, etc. Attempt to determine the
268 * minimum times. These can be subtracted from the profiling times
269 * without much risk of reducing the profiling times below what they
270 * would be when profiling is not configured. Abbreviate:
271 * ab = minimum time between MC1 and MC3
272 * a = minimum time between MC1 and MC2
273 * b = minimum time between MC2 and MC3
274 * cd = minimum time between ME1 and ME3
275 * c = minimum time between ME1 and ME2
276 * d = minimum time between ME2 and ME3.
277 * These satisfy the relations:
278 * ab <= mcount_overhead (just measured)
279 * a + b <= ab
280 * cd <= mexitcount_overhead (just measured)
281 * c + d <= cd
282 * a + d <= nullfunc_loop_profiled_time (just measured)
283 * a >= 0, b >= 0, c >= 0, d >= 0.
284 * Assume that ab and cd are equal to the minimums.
285 */
286 p->cputime_overhead = CALIB_DOSCALE(cputime_overhead);
287 p->mcount_overhead = CALIB_DOSCALE(mcount_overhead - cputime_overhead);
288 p->mexitcount_overhead = CALIB_DOSCALE(mexitcount_overhead
289 - cputime_overhead);
290 nullfunc_loop_overhead = nullfunc_loop_profiled_time - empty_loop_time;
291 p->mexitcount_post_overhead = CALIB_DOSCALE((mcount_overhead
292 - nullfunc_loop_overhead)
293 / 4);
294 p->mexitcount_pre_overhead = p->mexitcount_overhead
295 + p->cputime_overhead
296 - p->mexitcount_post_overhead;
297 p->mcount_pre_overhead = CALIB_DOSCALE(nullfunc_loop_overhead)
298 - p->mexitcount_post_overhead;
299 p->mcount_post_overhead = p->mcount_overhead
300 + p->cputime_overhead
301 - p->mcount_pre_overhead;
302 printf(
303 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d nsec\n",
304 c2n(p->cputime_overhead, p->profrate),
305 c2n(p->mcount_overhead, p->profrate),
306 c2n(p->mcount_pre_overhead, p->profrate),
307 c2n(p->mcount_post_overhead, p->profrate),
308 c2n(p->cputime_overhead, p->profrate),
309 c2n(p->mexitcount_overhead, p->profrate),
310 c2n(p->mexitcount_pre_overhead, p->profrate),
311 c2n(p->mexitcount_post_overhead, p->profrate));
312 printf(
313 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d cycles\n",
314 p->cputime_overhead, p->mcount_overhead,
315 p->mcount_pre_overhead, p->mcount_post_overhead,
316 p->cputime_overhead, p->mexitcount_overhead,
317 p->mexitcount_pre_overhead, p->mexitcount_post_overhead);
318 #endif /* GUPROF */
319 }
320
321 /*
322 * Return kernel profiling information.
323 */
324 static int
325 sysctl_kern_prof(SYSCTL_HANDLER_ARGS)
326 {
327 int *name = (int *) arg1;
328 u_int namelen = arg2;
329 struct gmonparam *gp = &_gmonparam;
330 int error;
331 int state;
332
333 /* all sysctl names at this level are terminal */
334 if (namelen != 1)
335 return (ENOTDIR); /* overloaded */
336
337 switch (name[0]) {
338 case GPROF_STATE:
339 state = gp->state;
340 error = sysctl_handle_int(oidp, &state, 0, req);
341 if (error)
342 return (error);
343 if (!req->newptr)
344 return (0);
345 if (state == GMON_PROF_OFF) {
346 gp->state = state;
347 PROC_LOCK(&proc0);
348 stopprofclock(&proc0);
349 PROC_UNLOCK(&proc0);
350 stopguprof(gp);
351 } else if (state == GMON_PROF_ON) {
352 gp->state = GMON_PROF_OFF;
353 stopguprof(gp);
354 gp->profrate = profhz;
355 PROC_LOCK(&proc0);
356 startprofclock(&proc0);
357 PROC_UNLOCK(&proc0);
358 gp->state = state;
359 #ifdef GUPROF
360 } else if (state == GMON_PROF_HIRES) {
361 gp->state = GMON_PROF_OFF;
362 PROC_LOCK(&proc0);
363 stopprofclock(&proc0);
364 PROC_UNLOCK(&proc0);
365 startguprof(gp);
366 gp->state = state;
367 #endif
368 } else if (state != gp->state)
369 return (EINVAL);
370 return (0);
371 case GPROF_COUNT:
372 return (sysctl_handle_opaque(oidp,
373 gp->kcount, gp->kcountsize, req));
374 case GPROF_FROMS:
375 return (sysctl_handle_opaque(oidp,
376 gp->froms, gp->fromssize, req));
377 case GPROF_TOS:
378 return (sysctl_handle_opaque(oidp,
379 gp->tos, gp->tossize, req));
380 case GPROF_GMONPARAM:
381 return (sysctl_handle_opaque(oidp, gp, sizeof *gp, req));
382 default:
383 return (EOPNOTSUPP);
384 }
385 /* NOTREACHED */
386 }
387
388 static SYSCTL_NODE(_kern, KERN_PROF, prof, CTLFLAG_RW, sysctl_kern_prof, "");
389 #endif /* GPROF */
390
391 /*
392 * Profiling system call.
393 *
394 * The scale factor is a fixed point number with 16 bits of fraction, so that
395 * 1.0 is represented as 0x10000. A scale factor of 0 turns off profiling.
396 */
397 #ifndef _SYS_SYSPROTO_H_
398 struct profil_args {
399 caddr_t samples;
400 size_t size;
401 size_t offset;
402 u_int scale;
403 };
404 #endif
405 /* ARGSUSED */
406 int
407 sys_profil(struct thread *td, struct profil_args *uap)
408 {
409 struct uprof *upp;
410 struct proc *p;
411
412 if (uap->scale > (1 << 16))
413 return (EINVAL);
414
415 p = td->td_proc;
416 if (uap->scale == 0) {
417 PROC_LOCK(p);
418 stopprofclock(p);
419 PROC_UNLOCK(p);
420 return (0);
421 }
422 PROC_LOCK(p);
423 upp = &td->td_proc->p_stats->p_prof;
424 PROC_PROFLOCK(p);
425 upp->pr_off = uap->offset;
426 upp->pr_scale = uap->scale;
427 upp->pr_base = uap->samples;
428 upp->pr_size = uap->size;
429 PROC_PROFUNLOCK(p);
430 startprofclock(p);
431 PROC_UNLOCK(p);
432
433 return (0);
434 }
435
436 /*
437 * Scale is a fixed-point number with the binary point 16 bits
438 * into the value, and is <= 1.0. pc is at most 32 bits, so the
439 * intermediate result is at most 48 bits.
440 */
441 #define PC_TO_INDEX(pc, prof) \
442 ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \
443 (u_quad_t)((prof)->pr_scale)) >> 16) & ~1)
444
445 /*
446 * Collect user-level profiling statistics; called on a profiling tick,
447 * when a process is running in user-mode. This routine may be called
448 * from an interrupt context. We try to update the user profiling buffers
449 * cheaply with fuswintr() and suswintr(). If that fails, we revert to
450 * an AST that will vector us to trap() with a context in which copyin
451 * and copyout will work. Trap will then call addupc_task().
452 *
453 * Note that we may (rarely) not get around to the AST soon enough, and
454 * lose profile ticks when the next tick overwrites this one, but in this
455 * case the system is overloaded and the profile is probably already
456 * inaccurate.
457 */
458 void
459 addupc_intr(struct thread *td, uintfptr_t pc, u_int ticks)
460 {
461 struct uprof *prof;
462 caddr_t addr;
463 u_int i;
464 int v;
465
466 if (ticks == 0)
467 return;
468 prof = &td->td_proc->p_stats->p_prof;
469 PROC_PROFLOCK(td->td_proc);
470 if (pc < prof->pr_off ||
471 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size) {
472 PROC_PROFUNLOCK(td->td_proc);
473 return; /* out of range; ignore */
474 }
475
476 addr = prof->pr_base + i;
477 PROC_PROFUNLOCK(td->td_proc);
478 if ((v = fuswintr(addr)) == -1 || suswintr(addr, v + ticks) == -1) {
479 td->td_profil_addr = pc;
480 td->td_profil_ticks = ticks;
481 td->td_pflags |= TDP_OWEUPC;
482 thread_lock(td);
483 td->td_flags |= TDF_ASTPENDING;
484 thread_unlock(td);
485 }
486 }
487
488 /*
489 * Much like before, but we can afford to take faults here. If the
490 * update fails, we simply turn off profiling.
491 */
492 void
493 addupc_task(struct thread *td, uintfptr_t pc, u_int ticks)
494 {
495 struct proc *p = td->td_proc;
496 struct uprof *prof;
497 caddr_t addr;
498 u_int i;
499 u_short v;
500 int stop = 0;
501
502 if (ticks == 0)
503 return;
504
505 PROC_LOCK(p);
506 if (!(p->p_flag & P_PROFIL)) {
507 PROC_UNLOCK(p);
508 return;
509 }
510 p->p_profthreads++;
511 prof = &p->p_stats->p_prof;
512 PROC_PROFLOCK(p);
513 if (pc < prof->pr_off ||
514 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size) {
515 PROC_PROFUNLOCK(p);
516 goto out;
517 }
518
519 addr = prof->pr_base + i;
520 PROC_PROFUNLOCK(p);
521 PROC_UNLOCK(p);
522 if (copyin(addr, &v, sizeof(v)) == 0) {
523 v += ticks;
524 if (copyout(&v, addr, sizeof(v)) == 0) {
525 PROC_LOCK(p);
526 goto out;
527 }
528 }
529 stop = 1;
530 PROC_LOCK(p);
531
532 out:
533 if (--p->p_profthreads == 0) {
534 if (p->p_flag & P_STOPPROF) {
535 wakeup(&p->p_profthreads);
536 p->p_flag &= ~P_STOPPROF;
537 stop = 0;
538 }
539 }
540 if (stop)
541 stopprofclock(p);
542 PROC_UNLOCK(p);
543 }
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