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  * 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: src/sys/kern/subr_prof.c,v 1.32.2.2 2000/08/03 00:09:32 ps Exp $
  35  * $DragonFly: src/sys/kern/subr_prof.c,v 1.16 2007/01/06 03:23:18 dillon Exp $
  36  */
  37
  38 #include <sys/param.h>
  39 #include <sys/systm.h>
  40 #include <sys/sysproto.h>
  41 #include <sys/kernel.h>
  42 #include <sys/proc.h>
  43 #include <sys/resourcevar.h>
  44 #include <sys/sysctl.h>
  45 #include <sys/thread2.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(void)
  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(void)
  77 {
  78 }
  79 #endif /* GUPROF */
  80
  81 static void
  82 kmstartup(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         kprintf("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                 kprintf("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         cpu_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         cpu_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         kprintf("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         kprintf(
 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         kprintf(
 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 /* ARGSUSED */
 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         if (uap->scale == 0) {
 355                 stopprofclock(p);
 356                 return (0);
 357         }
 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         return (0);
 370 }
 371
 372 /*
 373  * Scale is a fixed-point number with the binary point 16 bits
 374  * into the value, and is <= 1.0.  pc is at most 32 bits, so the
 375  * intermediate result is at most 48 bits.
 376  */
 377 #define PC_TO_INDEX(pc, prof) \
 378         ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \
 379             (u_quad_t)((prof)->pr_scale)) >> 16) & ~1)
 380
 381 /*
 382  * Collect user-level profiling statistics; called on a profiling tick,
 383  * when a process is running in user-mode.  This routine may be called
 384  * from an interrupt context.  We try to update the user profiling buffers
 385  * cheaply with fuswintr() and suswintr().  If that fails, we revert to
 386  * an AST that will vector us to trap() with a context in which copyin
 387  * and copyout will work.  Trap will then call addupc_task().
 388  *
 389  * XXX fuswintr() and suswintr() never worked (always returnde -1), remove
 390  * them.  It's just a bad idea to try to do this from a hard interrupt.
 391  *
 392  * Note that we may (rarely) not get around to the AST soon enough, and
 393  * lose profile ticks when the next tick overwrites this one, but in this
 394  * case the system is overloaded and the profile is probably already
 395  * inaccurate.
 396  */
 397 void
 398 addupc_intr(struct proc *p, u_long pc, u_int ticks)
 399 {
 400         struct uprof *prof;
 401         caddr_t addr;
 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         addr = prof->pr_base + i;
 412         prof->pr_addr = pc;
 413         prof->pr_ticks = ticks;
 414         need_proftick();
 415 }
 416
 417 /*
 418  * Much like before, but we can afford to take faults here.  If the
 419  * update fails, we simply turn off profiling.
 420  */
 421 void
 422 addupc_task(struct proc *p, u_long pc, u_int ticks)
 423 {
 424         struct uprof *prof;
 425         caddr_t addr;
 426         u_int i;
 427         u_short v;
 428
 429         /* Testing P_PROFIL may be unnecessary, but is certainly safe. */
 430         if ((p->p_flag & P_PROFIL) == 0 || ticks == 0)
 431                 return;
 432
 433         prof = &p->p_prof;
 434         if (pc < prof->pr_off ||
 435             (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
 436                 return;
 437
 438         addr = prof->pr_base + i;
 439         if (copyin(addr, (caddr_t)&v, sizeof(v)) == 0) {
 440                 v += ticks;
 441                 if (copyout((caddr_t)&v, addr, sizeof(v)) == 0)
 442                         return;
 443         }
 444         stopprofclock(p);
 445 }