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. 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 * $FreeBSD: src/sys/kern/subr_prof.c,v 1.32.2.2 2000/08/03 00:09:32 ps Exp $ 31 */ 32 33 #include <sys/param.h> 34 #include <sys/systm.h> 35 #include <sys/sysproto.h> 36 #include <sys/kernel.h> 37 #include <sys/proc.h> 38 #include <sys/resourcevar.h> 39 #include <sys/sysctl.h> 40 41 #include <sys/thread2.h> 42 #include <sys/mplock2.h> 43 44 #include <machine/cpu.h> 45 46 #ifdef GPROF 47 #include <sys/malloc.h> 48 #include <sys/gmon.h> 49 #undef MCOUNT 50 51 static MALLOC_DEFINE(M_GPROF, "gprof", "kernel profiling buffer"); 52 53 static void kmstartup (void *); 54 SYSINIT(kmem, SI_SUB_KPROF, SI_ORDER_FIRST, kmstartup, NULL) 55 56 struct gmonparam _gmonparam = { GMON_PROF_OFF }; 57 58 #ifdef GUPROF 59 #include <machine/asmacros.h> 60 61 void 62 nullfunc_loop_profiled(void) 63 { 64 int i; 65 66 for (i = 0; i < CALIB_SCALE; i++) 67 nullfunc_profiled(); 68 } 69 70 #define nullfunc_loop_profiled_end nullfunc_profiled /* XXX */ 71 72 void 73 nullfunc_profiled(void) 74 { 75 } 76 #endif /* GUPROF */ 77 78 static void 79 kmstartup(void *dummy) 80 { 81 char *cp; 82 struct gmonparam *p = &_gmonparam; 83 #ifdef GUPROF 84 int cputime_overhead; 85 int empty_loop_time; 86 int i; 87 int mcount_overhead; 88 int mexitcount_overhead; 89 int nullfunc_loop_overhead; 90 int nullfunc_loop_profiled_time; 91 uintfptr_t tmp_addr; 92 #endif 93 94 /* 95 * Round lowpc and highpc to multiples of the density we're using 96 * so the rest of the scaling (here and in gprof) stays in ints. 97 */ 98 p->lowpc = ROUNDDOWN((u_long)btext, HISTFRACTION * sizeof(HISTCOUNTER)); 99 p->highpc = ROUNDUP((u_long)etext, HISTFRACTION * sizeof(HISTCOUNTER)); 100 p->textsize = p->highpc - p->lowpc; 101 kprintf("Profiling kernel, textsize=%lu [%jx..%jx]\n", 102 p->textsize, (uintmax_t)p->lowpc, (uintmax_t)p->highpc); 103 p->kcountsize = p->textsize / HISTFRACTION; 104 p->hashfraction = HASHFRACTION; 105 p->fromssize = p->textsize / HASHFRACTION; 106 p->tolimit = p->textsize * ARCDENSITY / 100; 107 if (p->tolimit < MINARCS) 108 p->tolimit = MINARCS; 109 else if (p->tolimit > MAXARCS) 110 p->tolimit = MAXARCS; 111 p->tossize = p->tolimit * sizeof(struct tostruct); 112 cp = (char *)kmalloc(p->kcountsize + p->fromssize + p->tossize, 113 M_GPROF, M_NOWAIT | M_ZERO); 114 if (cp == NULL) { 115 kprintf("No memory for profiling.\n"); 116 return; 117 } 118 p->tos = (struct tostruct *)cp; 119 cp += p->tossize; 120 p->kcount = (HISTCOUNTER *)cp; 121 cp += p->kcountsize; 122 p->froms = (u_short *)cp; 123 124 #ifdef GUPROF 125 /* Initialize pointers to overhead counters. */ 126 p->cputime_count = &KCOUNT(p, PC_TO_I(p, cputime)); 127 p->mcount_count = &KCOUNT(p, PC_TO_I(p, mcount)); 128 p->mexitcount_count = &KCOUNT(p, PC_TO_I(p, mexitcount)); 129 130 /* 131 * Disable interrupts to avoid interference while we calibrate 132 * things. 133 */ 134 cpu_disable_intr(); 135 136 /* 137 * Determine overheads. 138 * XXX this needs to be repeated for each useful timer/counter. 139 */ 140 cputime_overhead = 0; 141 startguprof(p); 142 for (i = 0; i < CALIB_SCALE; i++) 143 cputime_overhead += cputime(); 144 145 empty_loop(); 146 startguprof(p); 147 empty_loop(); 148 empty_loop_time = cputime(); 149 150 nullfunc_loop_profiled(); 151 152 /* 153 * Start profiling. There won't be any normal function calls since 154 * interrupts are disabled, but we will call the profiling routines 155 * directly to determine their overheads. 156 */ 157 p->state = GMON_PROF_HIRES; 158 159 startguprof(p); 160 nullfunc_loop_profiled(); 161 162 startguprof(p); 163 for (i = 0; i < CALIB_SCALE; i++) 164 #if defined(__i386__) && __GNUC__ >= 2 165 __asm("pushl %0; call __mcount; popl %%ecx" 166 : 167 : "i" (profil) 168 : "ax", "bx", "cx", "dx", "memory"); 169 #else 170 #error 171 #endif 172 mcount_overhead = KCOUNT(p, PC_TO_I(p, profil)); 173 174 startguprof(p); 175 for (i = 0; i < CALIB_SCALE; i++) 176 #if defined(__i386__) && __GNUC__ >= 2 177 __asm("call " __XSTRING(HIDENAME(mexitcount)) "; 1:" 178 : : : "ax", "bx", "cx", "dx", "memory"); 179 __asm("movl $1b,%0" : "=rm" (tmp_addr)); 180 #else 181 #error 182 #endif 183 mexitcount_overhead = KCOUNT(p, PC_TO_I(p, tmp_addr)); 184 185 p->state = GMON_PROF_OFF; 186 stopguprof(p); 187 188 cpu_enable_intr(); 189 190 nullfunc_loop_profiled_time = 0; 191 for (tmp_addr = (uintfptr_t)nullfunc_loop_profiled; 192 tmp_addr < (uintfptr_t)nullfunc_loop_profiled_end; 193 tmp_addr += HISTFRACTION * sizeof(HISTCOUNTER)) 194 nullfunc_loop_profiled_time += KCOUNT(p, PC_TO_I(p, tmp_addr)); 195 #define CALIB_DOSCALE(count) (((count) + CALIB_SCALE / 3) / CALIB_SCALE) 196 #define c2n(count, freq) ((int)((count) * 1000000000LL / freq)) 197 kprintf("cputime %d, empty_loop %d, nullfunc_loop_profiled %d, mcount %d, mexitcount %d\n", 198 CALIB_DOSCALE(c2n(cputime_overhead, p->profrate)), 199 CALIB_DOSCALE(c2n(empty_loop_time, p->profrate)), 200 CALIB_DOSCALE(c2n(nullfunc_loop_profiled_time, p->profrate)), 201 CALIB_DOSCALE(c2n(mcount_overhead, p->profrate)), 202 CALIB_DOSCALE(c2n(mexitcount_overhead, p->profrate))); 203 cputime_overhead -= empty_loop_time; 204 mcount_overhead -= empty_loop_time; 205 mexitcount_overhead -= empty_loop_time; 206 207 /*- 208 * Profiling overheads are determined by the times between the 209 * following events: 210 * MC1: mcount() is called 211 * MC2: cputime() (called from mcount()) latches the timer 212 * MC3: mcount() completes 213 * ME1: mexitcount() is called 214 * ME2: cputime() (called from mexitcount()) latches the timer 215 * ME3: mexitcount() completes. 216 * The times between the events vary slightly depending on instruction 217 * combination and cache misses, etc. Attempt to determine the 218 * minimum times. These can be subtracted from the profiling times 219 * without much risk of reducing the profiling times below what they 220 * would be when profiling is not configured. Abbreviate: 221 * ab = minimum time between MC1 and MC3 222 * a = minumum time between MC1 and MC2 223 * b = minimum time between MC2 and MC3 224 * cd = minimum time between ME1 and ME3 225 * c = minimum time between ME1 and ME2 226 * d = minimum time between ME2 and ME3. 227 * These satisfy the relations: 228 * ab <= mcount_overhead (just measured) 229 * a + b <= ab 230 * cd <= mexitcount_overhead (just measured) 231 * c + d <= cd 232 * a + d <= nullfunc_loop_profiled_time (just measured) 233 * a >= 0, b >= 0, c >= 0, d >= 0. 234 * Assume that ab and cd are equal to the minimums. 235 */ 236 p->cputime_overhead = CALIB_DOSCALE(cputime_overhead); 237 p->mcount_overhead = CALIB_DOSCALE(mcount_overhead - cputime_overhead); 238 p->mexitcount_overhead = CALIB_DOSCALE(mexitcount_overhead 239 - cputime_overhead); 240 nullfunc_loop_overhead = nullfunc_loop_profiled_time - empty_loop_time; 241 p->mexitcount_post_overhead = CALIB_DOSCALE((mcount_overhead 242 - nullfunc_loop_overhead) 243 / 4); 244 p->mexitcount_pre_overhead = p->mexitcount_overhead 245 + p->cputime_overhead 246 - p->mexitcount_post_overhead; 247 p->mcount_pre_overhead = CALIB_DOSCALE(nullfunc_loop_overhead) 248 - p->mexitcount_post_overhead; 249 p->mcount_post_overhead = p->mcount_overhead 250 + p->cputime_overhead 251 - p->mcount_pre_overhead; 252 kprintf( 253 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d nsec\n", 254 c2n(p->cputime_overhead, p->profrate), 255 c2n(p->mcount_overhead, p->profrate), 256 c2n(p->mcount_pre_overhead, p->profrate), 257 c2n(p->mcount_post_overhead, p->profrate), 258 c2n(p->cputime_overhead, p->profrate), 259 c2n(p->mexitcount_overhead, p->profrate), 260 c2n(p->mexitcount_pre_overhead, p->profrate), 261 c2n(p->mexitcount_post_overhead, p->profrate)); 262 kprintf( 263 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d cycles\n", 264 p->cputime_overhead, p->mcount_overhead, 265 p->mcount_pre_overhead, p->mcount_post_overhead, 266 p->cputime_overhead, p->mexitcount_overhead, 267 p->mexitcount_pre_overhead, p->mexitcount_post_overhead); 268 #endif /* GUPROF */ 269 } 270 271 /* 272 * Return kernel profiling information. 273 */ 274 static int 275 sysctl_kern_prof(SYSCTL_HANDLER_ARGS) 276 { 277 int *name = (int *) arg1; 278 u_int namelen = arg2; 279 struct gmonparam *gp = &_gmonparam; 280 int error; 281 int state; 282 283 /* all sysctl names at this level are terminal */ 284 if (namelen != 1) 285 return (ENOTDIR); /* overloaded */ 286 287 switch (name[0]) { 288 case GPROF_STATE: 289 state = gp->state; 290 error = sysctl_handle_int(oidp, &state, 0, req); 291 if (error) 292 return (error); 293 if (!req->newptr) 294 return (0); 295 lwkt_gettoken(&proc0.p_token); 296 if (state == GMON_PROF_OFF) { 297 gp->state = state; 298 stopprofclock(&proc0); 299 stopguprof(gp); 300 } else if (state == GMON_PROF_ON) { 301 gp->state = GMON_PROF_OFF; 302 stopguprof(gp); 303 gp->profrate = profhz; 304 startprofclock(&proc0); 305 gp->state = state; 306 #ifdef GUPROF 307 } else if (state == GMON_PROF_HIRES) { 308 gp->state = GMON_PROF_OFF; 309 stopprofclock(&proc0); 310 startguprof(gp); 311 gp->state = state; 312 #endif 313 } else if (state != gp->state) { 314 error = EINVAL; 315 } 316 lwkt_reltoken(&proc0.p_token); 317 return (error); 318 case GPROF_COUNT: 319 return (sysctl_handle_opaque(oidp, 320 gp->kcount, gp->kcountsize, req)); 321 case GPROF_FROMS: 322 return (sysctl_handle_opaque(oidp, 323 gp->froms, gp->fromssize, req)); 324 case GPROF_TOS: 325 return (sysctl_handle_opaque(oidp, 326 gp->tos, gp->tossize, req)); 327 case GPROF_GMONPARAM: 328 return (sysctl_handle_opaque(oidp, gp, sizeof *gp, req)); 329 default: 330 return (EOPNOTSUPP); 331 } 332 /* NOTREACHED */ 333 } 334 335 SYSCTL_NODE(_kern, KERN_PROF, prof, CTLFLAG_RW, sysctl_kern_prof, ""); 336 #endif /* GPROF */ 337 338 /* 339 * Profiling system call. 340 * 341 * The scale factor is a fixed point number with 16 bits of fraction, so that 342 * 1.0 is represented as 0x10000. A scale factor of 0 turns off profiling. 343 * 344 * MPALMOSTSAFE 345 */ 346 int 347 sys_profil(struct profil_args *uap) 348 { 349 struct proc *p = curproc; 350 struct uprof *upp; 351 352 if (uap->scale > (1 << 16)) 353 return (EINVAL); 354 get_mplock(); 355 if (uap->scale == 0) { 356 stopprofclock(p); 357 } else { 358 upp = &p->p_prof; 359 360 /* Block profile interrupts while changing state. */ 361 crit_enter(); 362 upp->pr_off = uap->offset; 363 upp->pr_scale = uap->scale; 364 upp->pr_base = uap->samples; 365 upp->pr_size = uap->size; 366 startprofclock(p); 367 crit_exit(); 368 } 369 rel_mplock(); 370 return (0); 371 } 372 373 /* 374 * Scale is a fixed-point number with the binary point 16 bits 375 * into the value, and is <= 1.0. pc is at most 32 bits, so the 376 * intermediate result is at most 48 bits. 377 */ 378 #define PC_TO_INDEX(pc, prof) \ 379 ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \ 380 (u_quad_t)((prof)->pr_scale)) >> 16) & ~1) 381 382 /* 383 * Collect user-level profiling statistics; called on a profiling tick, 384 * when a process is running in user-mode. This routine may be called 385 * from an interrupt context. We try to update the user profiling buffers 386 * cheaply with fuswintr() and suswintr(). If that fails, we revert to 387 * an AST that will vector us to trap() with a context in which copyin 388 * and copyout will work. Trap will then call addupc_task(). 389 * 390 * XXX fuswintr() and suswintr() never worked (always returnde -1), remove 391 * them. It's just a bad idea to try to do this from a hard interrupt. 392 * 393 * Note that we may (rarely) not get around to the AST soon enough, and 394 * lose profile ticks when the next tick overwrites this one, but in this 395 * case the system is overloaded and the profile is probably already 396 * inaccurate. 397 */ 398 void 399 addupc_intr(struct proc *p, u_long pc, u_int ticks) 400 { 401 struct uprof *prof; 402 u_int i; 403 404 if (ticks == 0) 405 return; 406 prof = &p->p_prof; 407 if (pc < prof->pr_off || 408 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size) 409 return; /* out of range; ignore */ 410 411 prof->pr_addr = pc; 412 prof->pr_ticks = ticks; 413 need_proftick(); 414 } 415 416 /* 417 * Much like before, but we can afford to take faults here. If the 418 * update fails, we simply turn off profiling. 419 */ 420 void 421 addupc_task(struct proc *p, u_long pc, u_int ticks) 422 { 423 struct uprof *prof; 424 caddr_t addr; 425 u_int i; 426 u_short v; 427 428 /* Testing P_PROFIL may be unnecessary, but is certainly safe. */ 429 if ((p->p_flags & P_PROFIL) == 0 || ticks == 0) 430 return; 431 432 prof = &p->p_prof; 433 if (pc < prof->pr_off || 434 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size) 435 return; 436 437 addr = prof->pr_base + i; 438 if (copyin(addr, (caddr_t)&v, sizeof(v)) == 0) { 439 v += ticks; 440 if (copyout((caddr_t)&v, addr, sizeof(v)) == 0) 441 return; 442 } 443 stopprofclock(p); 444 }
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