Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_prof.c
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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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)subr_prof.c 8.3 (Berkeley) 9/23/93 34 * $FreeBSD: releng/5.0/sys/kern/subr_prof.c 104285 2002-10-01 13:15:11Z phk $ 35 */ 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/sysproto.h> 40 #include <sys/kernel.h> 41 #include <sys/lock.h> 42 #include <sys/mutex.h> 43 #include <sys/proc.h> 44 #include <sys/resourcevar.h> 45 #include <sys/sysctl.h> 46 47 #include <machine/cpu.h> 48 49 #ifdef GPROF 50 #include <sys/malloc.h> 51 #include <sys/gmon.h> 52 #undef MCOUNT 53 54 static MALLOC_DEFINE(M_GPROF, "gprof", "kernel profiling buffer"); 55 56 static void kmstartup(void *); 57 SYSINIT(kmem, SI_SUB_KPROF, SI_ORDER_FIRST, kmstartup, NULL) 58 59 struct gmonparam _gmonparam = { GMON_PROF_OFF }; 60 61 #ifdef GUPROF 62 #include <machine/asmacros.h> 63 64 void 65 nullfunc_loop_profiled() 66 { 67 int i; 68 69 for (i = 0; i < CALIB_SCALE; i++) 70 nullfunc_profiled(); 71 } 72 73 #define nullfunc_loop_profiled_end nullfunc_profiled /* XXX */ 74 75 void 76 nullfunc_profiled() 77 { 78 } 79 #endif /* GUPROF */ 80 81 /* 82 * Update the histograms to support extending the text region arbitrarily. 83 * This is done slightly naively (no sparse regions), so will waste slight 84 * amounts of memory, but will overall work nicely enough to allow profiling 85 * of KLDs. 86 */ 87 void 88 kmupetext(uintfptr_t nhighpc) 89 { 90 struct gmonparam np; /* slightly large */ 91 struct gmonparam *p = &_gmonparam; 92 char *cp; 93 94 GIANT_REQUIRED; 95 bcopy(p, &np, sizeof(*p)); 96 np.highpc = ROUNDUP(nhighpc, HISTFRACTION * sizeof(HISTCOUNTER)); 97 if (np.highpc <= p->highpc) 98 return; 99 np.textsize = np.highpc - p->lowpc; 100 np.kcountsize = np.textsize / HISTFRACTION; 101 np.hashfraction = HASHFRACTION; 102 np.fromssize = np.textsize / HASHFRACTION; 103 np.tolimit = np.textsize * ARCDENSITY / 100; 104 if (np.tolimit < MINARCS) 105 np.tolimit = MINARCS; 106 else if (np.tolimit > MAXARCS) 107 np.tolimit = MAXARCS; 108 np.tossize = np.tolimit * sizeof(struct tostruct); 109 cp = malloc(np.kcountsize + np.fromssize + np.tossize, 110 M_GPROF, M_WAITOK); 111 /* 112 * Check for something else extending highpc while we slept. 113 */ 114 if (np.highpc <= p->highpc) { 115 free(cp, M_GPROF); 116 return; 117 } 118 np.tos = (struct tostruct *)cp; 119 cp += np.tossize; 120 np.kcount = (HISTCOUNTER *)cp; 121 cp += np.kcountsize; 122 np.froms = (u_short *)cp; 123 #ifdef GUPROF 124 /* Reinitialize pointers to overhead counters. */ 125 np.cputime_count = &KCOUNT(&np, PC_TO_I(&np, cputime)); 126 np.mcount_count = &KCOUNT(&np, PC_TO_I(&np, mcount)); 127 np.mexitcount_count = &KCOUNT(&np, PC_TO_I(&np, mexitcount)); 128 #endif 129 critical_enter(); 130 bcopy(p->tos, np.tos, p->tossize); 131 bzero((char *)np.tos + p->tossize, np.tossize - p->tossize); 132 bcopy(p->kcount, np.kcount, p->kcountsize); 133 bzero((char *)np.kcount + p->kcountsize, np.kcountsize - 134 p->kcountsize); 135 bcopy(p->froms, np.froms, p->fromssize); 136 bzero((char *)np.froms + p->fromssize, np.fromssize - p->fromssize); 137 cp = (char *)p->tos; 138 bcopy(&np, p, sizeof(*p)); 139 critical_exit(); 140 free(cp, M_GPROF); 141 } 142 143 static void 144 kmstartup(dummy) 145 void *dummy; 146 { 147 char *cp; 148 struct gmonparam *p = &_gmonparam; 149 #ifdef GUPROF 150 int cputime_overhead; 151 int empty_loop_time; 152 int i; 153 int mcount_overhead; 154 int mexitcount_overhead; 155 int nullfunc_loop_overhead; 156 int nullfunc_loop_profiled_time; 157 uintfptr_t tmp_addr; 158 #endif 159 160 /* 161 * Round lowpc and highpc to multiples of the density we're using 162 * so the rest of the scaling (here and in gprof) stays in ints. 163 */ 164 p->lowpc = ROUNDDOWN((u_long)btext, HISTFRACTION * sizeof(HISTCOUNTER)); 165 p->highpc = ROUNDUP((u_long)etext, HISTFRACTION * sizeof(HISTCOUNTER)); 166 p->textsize = p->highpc - p->lowpc; 167 printf("Profiling kernel, textsize=%lu [%x..%x]\n", 168 p->textsize, p->lowpc, p->highpc); 169 p->kcountsize = p->textsize / HISTFRACTION; 170 p->hashfraction = HASHFRACTION; 171 p->fromssize = p->textsize / HASHFRACTION; 172 p->tolimit = p->textsize * ARCDENSITY / 100; 173 if (p->tolimit < MINARCS) 174 p->tolimit = MINARCS; 175 else if (p->tolimit > MAXARCS) 176 p->tolimit = MAXARCS; 177 p->tossize = p->tolimit * sizeof(struct tostruct); 178 cp = (char *)malloc(p->kcountsize + p->fromssize + p->tossize, 179 M_GPROF, M_WAITOK | M_ZERO); 180 p->tos = (struct tostruct *)cp; 181 cp += p->tossize; 182 p->kcount = (HISTCOUNTER *)cp; 183 cp += p->kcountsize; 184 p->froms = (u_short *)cp; 185 186 #ifdef GUPROF 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 #if defined(__i386__) && __GNUC__ >= 2 227 __asm("pushl %0; call __mcount; popl %%ecx" 228 : 229 : "i" (profil) 230 : "ax", "bx", "cx", "dx", "memory"); 231 #elif defined(lint) 232 #else 233 #error 234 #endif 235 mcount_overhead = KCOUNT(p, PC_TO_I(p, profil)); 236 237 startguprof(p); 238 for (i = 0; i < CALIB_SCALE; i++) 239 #if defined(__i386__) && __GNUC__ >= 2 240 __asm("call " __XSTRING(HIDENAME(mexitcount)) "; 1:" 241 : : : "ax", "bx", "cx", "dx", "memory"); 242 __asm("movl $1b,%0" : "=rm" (tmp_addr)); 243 #elif defined(lint) 244 #else 245 #error 246 #endif 247 mexitcount_overhead = KCOUNT(p, PC_TO_I(p, tmp_addr)); 248 249 p->state = GMON_PROF_OFF; 250 stopguprof(p); 251 252 critical_exit(); 253 254 nullfunc_loop_profiled_time = 0; 255 for (tmp_addr = (uintfptr_t)nullfunc_loop_profiled; 256 tmp_addr < (uintfptr_t)nullfunc_loop_profiled_end; 257 tmp_addr += HISTFRACTION * sizeof(HISTCOUNTER)) 258 nullfunc_loop_profiled_time += KCOUNT(p, PC_TO_I(p, tmp_addr)); 259 #define CALIB_DOSCALE(count) (((count) + CALIB_SCALE / 3) / CALIB_SCALE) 260 #define c2n(count, freq) ((int)((count) * 1000000000LL / freq)) 261 printf("cputime %d, empty_loop %d, nullfunc_loop_profiled %d, mcount %d, mexitcount %d\n", 262 CALIB_DOSCALE(c2n(cputime_overhead, p->profrate)), 263 CALIB_DOSCALE(c2n(empty_loop_time, p->profrate)), 264 CALIB_DOSCALE(c2n(nullfunc_loop_profiled_time, p->profrate)), 265 CALIB_DOSCALE(c2n(mcount_overhead, p->profrate)), 266 CALIB_DOSCALE(c2n(mexitcount_overhead, p->profrate))); 267 cputime_overhead -= empty_loop_time; 268 mcount_overhead -= empty_loop_time; 269 mexitcount_overhead -= empty_loop_time; 270 271 /*- 272 * Profiling overheads are determined by the times between the 273 * following events: 274 * MC1: mcount() is called 275 * MC2: cputime() (called from mcount()) latches the timer 276 * MC3: mcount() completes 277 * ME1: mexitcount() is called 278 * ME2: cputime() (called from mexitcount()) latches the timer 279 * ME3: mexitcount() completes. 280 * The times between the events vary slightly depending on instruction 281 * combination and cache misses, etc. Attempt to determine the 282 * minimum times. These can be subtracted from the profiling times 283 * without much risk of reducing the profiling times below what they 284 * would be when profiling is not configured. Abbreviate: 285 * ab = minimum time between MC1 and MC3 286 * a = minumum time between MC1 and MC2 287 * b = minimum time between MC2 and MC3 288 * cd = minimum time between ME1 and ME3 289 * c = minimum time between ME1 and ME2 290 * d = minimum time between ME2 and ME3. 291 * These satisfy the relations: 292 * ab <= mcount_overhead (just measured) 293 * a + b <= ab 294 * cd <= mexitcount_overhead (just measured) 295 * c + d <= cd 296 * a + d <= nullfunc_loop_profiled_time (just measured) 297 * a >= 0, b >= 0, c >= 0, d >= 0. 298 * Assume that ab and cd are equal to the minimums. 299 */ 300 p->cputime_overhead = CALIB_DOSCALE(cputime_overhead); 301 p->mcount_overhead = CALIB_DOSCALE(mcount_overhead - cputime_overhead); 302 p->mexitcount_overhead = CALIB_DOSCALE(mexitcount_overhead 303 - cputime_overhead); 304 nullfunc_loop_overhead = nullfunc_loop_profiled_time - empty_loop_time; 305 p->mexitcount_post_overhead = CALIB_DOSCALE((mcount_overhead 306 - nullfunc_loop_overhead) 307 / 4); 308 p->mexitcount_pre_overhead = p->mexitcount_overhead 309 + p->cputime_overhead 310 - p->mexitcount_post_overhead; 311 p->mcount_pre_overhead = CALIB_DOSCALE(nullfunc_loop_overhead) 312 - p->mexitcount_post_overhead; 313 p->mcount_post_overhead = p->mcount_overhead 314 + p->cputime_overhead 315 - p->mcount_pre_overhead; 316 printf( 317 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d nsec\n", 318 c2n(p->cputime_overhead, p->profrate), 319 c2n(p->mcount_overhead, p->profrate), 320 c2n(p->mcount_pre_overhead, p->profrate), 321 c2n(p->mcount_post_overhead, p->profrate), 322 c2n(p->cputime_overhead, p->profrate), 323 c2n(p->mexitcount_overhead, p->profrate), 324 c2n(p->mexitcount_pre_overhead, p->profrate), 325 c2n(p->mexitcount_post_overhead, p->profrate)); 326 printf( 327 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d cycles\n", 328 p->cputime_overhead, p->mcount_overhead, 329 p->mcount_pre_overhead, p->mcount_post_overhead, 330 p->cputime_overhead, p->mexitcount_overhead, 331 p->mexitcount_pre_overhead, p->mexitcount_post_overhead); 332 #endif /* GUPROF */ 333 } 334 335 /* 336 * Return kernel profiling information. 337 */ 338 static int 339 sysctl_kern_prof(SYSCTL_HANDLER_ARGS) 340 { 341 int *name = (int *) arg1; 342 u_int namelen = arg2; 343 struct gmonparam *gp = &_gmonparam; 344 int error; 345 int state; 346 347 /* all sysctl names at this level are terminal */ 348 if (namelen != 1) 349 return (ENOTDIR); /* overloaded */ 350 351 switch (name[0]) { 352 case GPROF_STATE: 353 state = gp->state; 354 error = sysctl_handle_int(oidp, &state, 0, req); 355 if (error) 356 return (error); 357 if (!req->newptr) 358 return (0); 359 if (state == GMON_PROF_OFF) { 360 gp->state = state; 361 stopprofclock(&proc0); 362 stopguprof(gp); 363 } else if (state == GMON_PROF_ON) { 364 gp->state = GMON_PROF_OFF; 365 stopguprof(gp); 366 gp->profrate = profhz; 367 startprofclock(&proc0); 368 gp->state = state; 369 #ifdef GUPROF 370 } else if (state == GMON_PROF_HIRES) { 371 gp->state = GMON_PROF_OFF; 372 stopprofclock(&proc0); 373 startguprof(gp); 374 gp->state = state; 375 #endif 376 } else if (state != gp->state) 377 return (EINVAL); 378 return (0); 379 case GPROF_COUNT: 380 return (sysctl_handle_opaque(oidp, 381 gp->kcount, gp->kcountsize, req)); 382 case GPROF_FROMS: 383 return (sysctl_handle_opaque(oidp, 384 gp->froms, gp->fromssize, req)); 385 case GPROF_TOS: 386 return (sysctl_handle_opaque(oidp, 387 gp->tos, gp->tossize, req)); 388 case GPROF_GMONPARAM: 389 return (sysctl_handle_opaque(oidp, gp, sizeof *gp, req)); 390 default: 391 return (EOPNOTSUPP); 392 } 393 /* NOTREACHED */ 394 } 395 396 SYSCTL_NODE(_kern, KERN_PROF, prof, CTLFLAG_RW, sysctl_kern_prof, ""); 397 #endif /* GPROF */ 398 399 /* 400 * Profiling system call. 401 * 402 * The scale factor is a fixed point number with 16 bits of fraction, so that 403 * 1.0 is represented as 0x10000. A scale factor of 0 turns off profiling. 404 */ 405 #ifndef _SYS_SYSPROTO_H_ 406 struct profil_args { 407 caddr_t samples; 408 size_t size; 409 size_t offset; 410 u_int scale; 411 }; 412 #endif 413 /* 414 * MPSAFE 415 */ 416 /* ARGSUSED */ 417 int 418 profil(td, uap) 419 struct thread *td; 420 register struct profil_args *uap; 421 { 422 register struct uprof *upp; 423 int s; 424 int error = 0; 425 426 mtx_lock(&Giant); 427 428 if (uap->scale > (1 << 16)) { 429 error = EINVAL; 430 goto done2; 431 } 432 if (uap->scale == 0) { 433 stopprofclock(td->td_proc); 434 goto done2; 435 } 436 upp = &td->td_proc->p_stats->p_prof; 437 438 /* Block profile interrupts while changing state. */ 439 s = splstatclock(); 440 upp->pr_off = uap->offset; 441 upp->pr_scale = uap->scale; 442 upp->pr_base = uap->samples; 443 upp->pr_size = uap->size; 444 startprofclock(td->td_proc); 445 splx(s); 446 447 done2: 448 mtx_unlock(&Giant); 449 return (error); 450 } 451 452 /* 453 * Scale is a fixed-point number with the binary point 16 bits 454 * into the value, and is <= 1.0. pc is at most 32 bits, so the 455 * intermediate result is at most 48 bits. 456 */ 457 #define PC_TO_INDEX(pc, prof) \ 458 ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \ 459 (u_quad_t)((prof)->pr_scale)) >> 16) & ~1) 460 461 /* 462 * Collect user-level profiling statistics; called on a profiling tick, 463 * when a process is running in user-mode. This routine may be called 464 * from an interrupt context. We try to update the user profiling buffers 465 * cheaply with fuswintr() and suswintr(). If that fails, we revert to 466 * an AST that will vector us to trap() with a context in which copyin 467 * and copyout will work. Trap will then call addupc_task(). 468 * 469 * Note that we may (rarely) not get around to the AST soon enough, and 470 * lose profile ticks when the next tick overwrites this one, but in this 471 * case the system is overloaded and the profile is probably already 472 * inaccurate. 473 */ 474 void 475 addupc_intr(ke, pc, ticks) 476 register struct kse *ke; 477 register uintptr_t pc; 478 u_int ticks; 479 { 480 register struct uprof *prof; 481 register caddr_t addr; 482 register u_int i; 483 register int v; 484 485 if (ticks == 0) 486 return; 487 prof = &ke->ke_proc->p_stats->p_prof; 488 if (pc < prof->pr_off || 489 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size) 490 return; /* out of range; ignore */ 491 492 addr = prof->pr_base + i; 493 if ((v = fuswintr(addr)) == -1 || suswintr(addr, v + ticks) == -1) { 494 mtx_lock_spin(&sched_lock); 495 prof->pr_addr = pc; 496 prof->pr_ticks = ticks; 497 ke->ke_flags |= KEF_OWEUPC | KEF_ASTPENDING ; 498 mtx_unlock_spin(&sched_lock); 499 } 500 } 501 502 /* 503 * Much like before, but we can afford to take faults here. If the 504 * update fails, we simply turn off profiling. 505 */ 506 void 507 addupc_task(ke, pc, ticks) 508 register struct kse *ke; 509 register uintptr_t pc; 510 u_int ticks; 511 { 512 struct proc *p = ke->ke_proc; 513 register struct uprof *prof; 514 register caddr_t addr; 515 register u_int i; 516 u_short v; 517 518 if (ticks == 0) 519 return; 520 521 prof = &p->p_stats->p_prof; 522 if (pc < prof->pr_off || 523 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size) 524 return; 525 526 addr = prof->pr_base + i; 527 if (copyin(addr, &v, sizeof(v)) == 0) { 528 v += ticks; 529 if (copyout(&v, addr, sizeof(v)) == 0) 530 return; 531 } 532 stopprofclock(p); 533 }
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