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 * $FreeBSD$ 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/proc.h> 42 #include <sys/resourcevar.h> 43 #include <sys/sysctl.h> 44 45 #include <machine/ipl.h> 46 #include <machine/cpu.h> 47 48 #ifdef GPROF 49 #include <sys/malloc.h> 50 #include <sys/gmon.h> 51 #undef MCOUNT 52 53 static MALLOC_DEFINE(M_GPROF, "gprof", "kernel profiling buffer"); 54 55 static void kmstartup __P((void *)); 56 SYSINIT(kmem, SI_SUB_KPROF, SI_ORDER_FIRST, kmstartup, NULL) 57 58 struct gmonparam _gmonparam = { GMON_PROF_OFF }; 59 60 #ifdef GUPROF 61 #include <machine/asmacros.h> 62 63 void 64 nullfunc_loop_profiled() 65 { 66 int i; 67 68 for (i = 0; i < CALIB_SCALE; i++) 69 nullfunc_profiled(); 70 } 71 72 #define nullfunc_loop_profiled_end nullfunc_profiled /* XXX */ 73 74 void 75 nullfunc_profiled() 76 { 77 } 78 #endif /* GUPROF */ 79 80 static void 81 kmstartup(dummy) 82 void *dummy; 83 { 84 char *cp; 85 struct gmonparam *p = &_gmonparam; 86 #ifdef GUPROF 87 int cputime_overhead; 88 int empty_loop_time; 89 int i; 90 int mcount_overhead; 91 int mexitcount_overhead; 92 int nullfunc_loop_overhead; 93 int nullfunc_loop_profiled_time; 94 uintfptr_t tmp_addr; 95 #endif 96 97 /* 98 * Round lowpc and highpc to multiples of the density we're using 99 * so the rest of the scaling (here and in gprof) stays in ints. 100 */ 101 p->lowpc = ROUNDDOWN((u_long)btext, HISTFRACTION * sizeof(HISTCOUNTER)); 102 p->highpc = ROUNDUP((u_long)etext, HISTFRACTION * sizeof(HISTCOUNTER)); 103 p->textsize = p->highpc - p->lowpc; 104 printf("Profiling kernel, textsize=%lu [%x..%x]\n", 105 p->textsize, p->lowpc, p->highpc); 106 p->kcountsize = p->textsize / HISTFRACTION; 107 p->hashfraction = HASHFRACTION; 108 p->fromssize = p->textsize / HASHFRACTION; 109 p->tolimit = p->textsize * ARCDENSITY / 100; 110 if (p->tolimit < MINARCS) 111 p->tolimit = MINARCS; 112 else if (p->tolimit > MAXARCS) 113 p->tolimit = MAXARCS; 114 p->tossize = p->tolimit * sizeof(struct tostruct); 115 cp = (char *)malloc(p->kcountsize + p->fromssize + p->tossize, 116 M_GPROF, M_NOWAIT); 117 if (cp == 0) { 118 printf("No memory for profiling.\n"); 119 return; 120 } 121 bzero(cp, p->kcountsize + p->tossize + p->fromssize); 122 p->tos = (struct tostruct *)cp; 123 cp += p->tossize; 124 p->kcount = (HISTCOUNTER *)cp; 125 cp += p->kcountsize; 126 p->froms = (u_short *)cp; 127 128 #ifdef GUPROF 129 /* Initialize pointers to overhead counters. */ 130 p->cputime_count = &KCOUNT(p, PC_TO_I(p, cputime)); 131 p->mcount_count = &KCOUNT(p, PC_TO_I(p, mcount)); 132 p->mexitcount_count = &KCOUNT(p, PC_TO_I(p, mexitcount)); 133 134 /* 135 * Disable interrupts to avoid interference while we calibrate 136 * things. 137 */ 138 disable_intr(); 139 140 /* 141 * Determine overheads. 142 * XXX this needs to be repeated for each useful timer/counter. 143 */ 144 cputime_overhead = 0; 145 startguprof(p); 146 for (i = 0; i < CALIB_SCALE; i++) 147 cputime_overhead += cputime(); 148 149 empty_loop(); 150 startguprof(p); 151 empty_loop(); 152 empty_loop_time = cputime(); 153 154 nullfunc_loop_profiled(); 155 156 /* 157 * Start profiling. There won't be any normal function calls since 158 * interrupts are disabled, but we will call the profiling routines 159 * directly to determine their overheads. 160 */ 161 p->state = GMON_PROF_HIRES; 162 163 startguprof(p); 164 nullfunc_loop_profiled(); 165 166 startguprof(p); 167 for (i = 0; i < CALIB_SCALE; i++) 168 #if defined(__i386__) && __GNUC__ >= 2 169 __asm("pushl %0; call __mcount; popl %%ecx" 170 : 171 : "i" (profil) 172 : "ax", "bx", "cx", "dx", "memory"); 173 #else 174 #error 175 #endif 176 mcount_overhead = KCOUNT(p, PC_TO_I(p, profil)); 177 178 startguprof(p); 179 for (i = 0; i < CALIB_SCALE; i++) 180 #if defined(__i386__) && __GNUC__ >= 2 181 __asm("call " __XSTRING(HIDENAME(mexitcount)) "; 1:" 182 : : : "ax", "bx", "cx", "dx", "memory"); 183 __asm("movl $1b,%0" : "=rm" (tmp_addr)); 184 #else 185 #error 186 #endif 187 mexitcount_overhead = KCOUNT(p, PC_TO_I(p, tmp_addr)); 188 189 p->state = GMON_PROF_OFF; 190 stopguprof(p); 191 192 enable_intr(); 193 194 nullfunc_loop_profiled_time = 0; 195 for (tmp_addr = (uintfptr_t)nullfunc_loop_profiled; 196 tmp_addr < (uintfptr_t)nullfunc_loop_profiled_end; 197 tmp_addr += HISTFRACTION * sizeof(HISTCOUNTER)) 198 nullfunc_loop_profiled_time += KCOUNT(p, PC_TO_I(p, tmp_addr)); 199 #define CALIB_DOSCALE(count) (((count) + CALIB_SCALE / 3) / CALIB_SCALE) 200 #define c2n(count, freq) ((int)((count) * 1000000000LL / freq)) 201 printf("cputime %d, empty_loop %d, nullfunc_loop_profiled %d, mcount %d, mexitcount %d\n", 202 CALIB_DOSCALE(c2n(cputime_overhead, p->profrate)), 203 CALIB_DOSCALE(c2n(empty_loop_time, p->profrate)), 204 CALIB_DOSCALE(c2n(nullfunc_loop_profiled_time, p->profrate)), 205 CALIB_DOSCALE(c2n(mcount_overhead, p->profrate)), 206 CALIB_DOSCALE(c2n(mexitcount_overhead, p->profrate))); 207 cputime_overhead -= empty_loop_time; 208 mcount_overhead -= empty_loop_time; 209 mexitcount_overhead -= empty_loop_time; 210 211 /*- 212 * Profiling overheads are determined by the times between the 213 * following events: 214 * MC1: mcount() is called 215 * MC2: cputime() (called from mcount()) latches the timer 216 * MC3: mcount() completes 217 * ME1: mexitcount() is called 218 * ME2: cputime() (called from mexitcount()) latches the timer 219 * ME3: mexitcount() completes. 220 * The times between the events vary slightly depending on instruction 221 * combination and cache misses, etc. Attempt to determine the 222 * minimum times. These can be subtracted from the profiling times 223 * without much risk of reducing the profiling times below what they 224 * would be when profiling is not configured. Abbreviate: 225 * ab = minimum time between MC1 and MC3 226 * a = minumum time between MC1 and MC2 227 * b = minimum time between MC2 and MC3 228 * cd = minimum time between ME1 and ME3 229 * c = minimum time between ME1 and ME2 230 * d = minimum time between ME2 and ME3. 231 * These satisfy the relations: 232 * ab <= mcount_overhead (just measured) 233 * a + b <= ab 234 * cd <= mexitcount_overhead (just measured) 235 * c + d <= cd 236 * a + d <= nullfunc_loop_profiled_time (just measured) 237 * a >= 0, b >= 0, c >= 0, d >= 0. 238 * Assume that ab and cd are equal to the minimums. 239 */ 240 p->cputime_overhead = CALIB_DOSCALE(cputime_overhead); 241 p->mcount_overhead = CALIB_DOSCALE(mcount_overhead - cputime_overhead); 242 p->mexitcount_overhead = CALIB_DOSCALE(mexitcount_overhead 243 - cputime_overhead); 244 nullfunc_loop_overhead = nullfunc_loop_profiled_time - empty_loop_time; 245 p->mexitcount_post_overhead = CALIB_DOSCALE((mcount_overhead 246 - nullfunc_loop_overhead) 247 / 4); 248 p->mexitcount_pre_overhead = p->mexitcount_overhead 249 + p->cputime_overhead 250 - p->mexitcount_post_overhead; 251 p->mcount_pre_overhead = CALIB_DOSCALE(nullfunc_loop_overhead) 252 - p->mexitcount_post_overhead; 253 p->mcount_post_overhead = p->mcount_overhead 254 + p->cputime_overhead 255 - p->mcount_pre_overhead; 256 printf( 257 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d nsec\n", 258 c2n(p->cputime_overhead, p->profrate), 259 c2n(p->mcount_overhead, p->profrate), 260 c2n(p->mcount_pre_overhead, p->profrate), 261 c2n(p->mcount_post_overhead, p->profrate), 262 c2n(p->cputime_overhead, p->profrate), 263 c2n(p->mexitcount_overhead, p->profrate), 264 c2n(p->mexitcount_pre_overhead, p->profrate), 265 c2n(p->mexitcount_post_overhead, p->profrate)); 266 printf( 267 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d cycles\n", 268 p->cputime_overhead, p->mcount_overhead, 269 p->mcount_pre_overhead, p->mcount_post_overhead, 270 p->cputime_overhead, p->mexitcount_overhead, 271 p->mexitcount_pre_overhead, p->mexitcount_post_overhead); 272 #endif /* GUPROF */ 273 } 274 275 /* 276 * Return kernel profiling information. 277 */ 278 static int 279 sysctl_kern_prof(SYSCTL_HANDLER_ARGS) 280 { 281 int *name = (int *) arg1; 282 u_int namelen = arg2; 283 struct gmonparam *gp = &_gmonparam; 284 int error; 285 int state; 286 287 /* all sysctl names at this level are terminal */ 288 if (namelen != 1) 289 return (ENOTDIR); /* overloaded */ 290 291 switch (name[0]) { 292 case GPROF_STATE: 293 state = gp->state; 294 error = sysctl_handle_int(oidp, &state, 0, req); 295 if (error) 296 return (error); 297 if (!req->newptr) 298 return (0); 299 if (state == GMON_PROF_OFF) { 300 gp->state = state; 301 stopprofclock(&proc0); 302 stopguprof(gp); 303 } else if (state == GMON_PROF_ON) { 304 gp->state = GMON_PROF_OFF; 305 stopguprof(gp); 306 gp->profrate = profhz; 307 startprofclock(&proc0); 308 gp->state = state; 309 #ifdef GUPROF 310 } else if (state == GMON_PROF_HIRES) { 311 gp->state = GMON_PROF_OFF; 312 stopprofclock(&proc0); 313 startguprof(gp); 314 gp->state = state; 315 #endif 316 } else if (state != gp->state) 317 return (EINVAL); 318 return (0); 319 case GPROF_COUNT: 320 return (sysctl_handle_opaque(oidp, 321 gp->kcount, gp->kcountsize, req)); 322 case GPROF_FROMS: 323 return (sysctl_handle_opaque(oidp, 324 gp->froms, gp->fromssize, req)); 325 case GPROF_TOS: 326 return (sysctl_handle_opaque(oidp, 327 gp->tos, gp->tossize, req)); 328 case GPROF_GMONPARAM: 329 return (sysctl_handle_opaque(oidp, gp, sizeof *gp, req)); 330 default: 331 return (EOPNOTSUPP); 332 } 333 /* NOTREACHED */ 334 } 335 336 SYSCTL_NODE(_kern, KERN_PROF, prof, CTLFLAG_RW, sysctl_kern_prof, ""); 337 #endif /* GPROF */ 338 339 /* 340 * Profiling system call. 341 * 342 * The scale factor is a fixed point number with 16 bits of fraction, so that 343 * 1.0 is represented as 0x10000. A scale factor of 0 turns off profiling. 344 */ 345 #ifndef _SYS_SYSPROTO_H_ 346 struct profil_args { 347 caddr_t samples; 348 size_t size; 349 size_t offset; 350 u_int scale; 351 }; 352 #endif 353 /* ARGSUSED */ 354 int 355 profil(p, uap) 356 struct proc *p; 357 register struct profil_args *uap; 358 { 359 register struct uprof *upp; 360 int s; 361 362 if (uap->scale > (1 << 16)) 363 return (EINVAL); 364 if (uap->scale == 0) { 365 stopprofclock(p); 366 return (0); 367 } 368 upp = &p->p_stats->p_prof; 369 370 /* Block profile interrupts while changing state. */ 371 s = splstatclock(); 372 upp->pr_off = uap->offset; 373 upp->pr_scale = uap->scale; 374 upp->pr_base = uap->samples; 375 upp->pr_size = uap->size; 376 startprofclock(p); 377 splx(s); 378 379 return (0); 380 } 381 382 /* 383 * Scale is a fixed-point number with the binary point 16 bits 384 * into the value, and is <= 1.0. pc is at most 32 bits, so the 385 * intermediate result is at most 48 bits. 386 */ 387 #define PC_TO_INDEX(pc, prof) \ 388 ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \ 389 (u_quad_t)((prof)->pr_scale)) >> 16) & ~1) 390 391 /* 392 * Collect user-level profiling statistics; called on a profiling tick, 393 * when a process is running in user-mode. This routine may be called 394 * from an interrupt context. We try to update the user profiling buffers 395 * cheaply with fuswintr() and suswintr(). If that fails, we revert to 396 * an AST that will vector us to trap() with a context in which copyin 397 * and copyout will work. Trap will then call addupc_task(). 398 * 399 * Note that we may (rarely) not get around to the AST soon enough, and 400 * lose profile ticks when the next tick overwrites this one, but in this 401 * case the system is overloaded and the profile is probably already 402 * inaccurate. 403 */ 404 void 405 addupc_intr(p, pc, ticks) 406 register struct proc *p; 407 register u_long pc; 408 u_int ticks; 409 { 410 register struct uprof *prof; 411 register caddr_t addr; 412 register u_int i; 413 register int v; 414 415 if (ticks == 0) 416 return; 417 prof = &p->p_stats->p_prof; 418 if (pc < prof->pr_off || 419 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size) 420 return; /* out of range; ignore */ 421 422 addr = prof->pr_base + i; 423 if ((v = fuswintr(addr)) == -1 || suswintr(addr, v + ticks) == -1) { 424 prof->pr_addr = pc; 425 prof->pr_ticks = ticks; 426 need_proftick(p); 427 } 428 } 429 430 /* 431 * Much like before, but we can afford to take faults here. If the 432 * update fails, we simply turn off profiling. 433 */ 434 void 435 addupc_task(p, pc, ticks) 436 register struct proc *p; 437 register u_long pc; 438 u_int ticks; 439 { 440 register struct uprof *prof; 441 register caddr_t addr; 442 register u_int i; 443 u_short v; 444 445 /* Testing P_PROFIL may be unnecessary, but is certainly safe. */ 446 if ((p->p_flag & P_PROFIL) == 0 || ticks == 0) 447 return; 448 449 prof = &p->p_stats->p_prof; 450 if (pc < prof->pr_off || 451 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size) 452 return; 453 454 addr = prof->pr_base + i; 455 if (copyin(addr, (caddr_t)&v, sizeof(v)) == 0) { 456 v += ticks; 457 if (copyout((caddr_t)&v, addr, sizeof(v)) == 0) 458 return; 459 } 460 stopprofclock(p); 461 }
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