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
  46 #include <sys/thread2.h>
  47 #include <sys/mplock2.h>
  48
  49 #include <machine/cpu.h>
  50
  51 #ifdef GPROF
  52 #include <sys/malloc.h>
  53 #include <sys/gmon.h>
  54 #undef MCOUNT
  55
  56 static MALLOC_DEFINE(M_GPROF, "gprof", "kernel profiling buffer");
  57
  58 static void kmstartup (void *);
  59 SYSINIT(kmem, SI_SUB_KPROF, SI_ORDER_FIRST, kmstartup, NULL)
  60
  61 struct gmonparam _gmonparam = { GMON_PROF_OFF };
  62
  63 #ifdef GUPROF
  64 #include <machine/asmacros.h>
  65
  66 void
  67 nullfunc_loop_profiled(void)
  68 {
  69         int i;
  70
  71         for (i = 0; i < CALIB_SCALE; i++)
  72                 nullfunc_profiled();
  73 }
  74
  75 #define nullfunc_loop_profiled_end      nullfunc_profiled       /* XXX */
  76
  77 void
  78 nullfunc_profiled(void)
  79 {
  80 }
  81 #endif /* GUPROF */
  82
  83 static void
  84 kmstartup(void *dummy)
  85 {
  86         char *cp;
  87         struct gmonparam *p = &_gmonparam;
  88 #ifdef GUPROF
  89         int cputime_overhead;
  90         int empty_loop_time;
  91         int i;
  92         int mcount_overhead;
  93         int mexitcount_overhead;
  94         int nullfunc_loop_overhead;
  95         int nullfunc_loop_profiled_time;
  96         uintfptr_t tmp_addr;
  97 #endif
  98
  99         /*
 100          * Round lowpc and highpc to multiples of the density we're using
 101          * so the rest of the scaling (here and in gprof) stays in ints.
 102          */
 103         p->lowpc = ROUNDDOWN((u_long)btext, HISTFRACTION * sizeof(HISTCOUNTER));
 104         p->highpc = ROUNDUP((u_long)etext, HISTFRACTION * sizeof(HISTCOUNTER));
 105         p->textsize = p->highpc - p->lowpc;
 106         kprintf("Profiling kernel, textsize=%lu [%x..%x]\n",
 107                p->textsize, p->lowpc, p->highpc);
 108         p->kcountsize = p->textsize / HISTFRACTION;
 109         p->hashfraction = HASHFRACTION;
 110         p->fromssize = p->textsize / HASHFRACTION;
 111         p->tolimit = p->textsize * ARCDENSITY / 100;
 112         if (p->tolimit < MINARCS)
 113                 p->tolimit = MINARCS;
 114         else if (p->tolimit > MAXARCS)
 115                 p->tolimit = MAXARCS;
 116         p->tossize = p->tolimit * sizeof(struct tostruct);
 117         cp = (char *)malloc(p->kcountsize + p->fromssize + p->tossize,
 118             M_GPROF, M_NOWAIT);
 119         if (cp == 0) {
 120                 kprintf("No memory for profiling.\n");
 121                 return;
 122         }
 123         bzero(cp, p->kcountsize + p->tossize + p->fromssize);
 124         p->tos = (struct tostruct *)cp;
 125         cp += p->tossize;
 126         p->kcount = (HISTCOUNTER *)cp;
 127         cp += p->kcountsize;
 128         p->froms = (u_short *)cp;
 129
 130 #ifdef GUPROF
 131         /* Initialize pointers to overhead counters. */
 132         p->cputime_count = &KCOUNT(p, PC_TO_I(p, cputime));
 133         p->mcount_count = &KCOUNT(p, PC_TO_I(p, mcount));
 134         p->mexitcount_count = &KCOUNT(p, PC_TO_I(p, mexitcount));
 135
 136         /*
 137          * Disable interrupts to avoid interference while we calibrate
 138          * things.
 139          */
 140         cpu_disable_intr();
 141
 142         /*
 143          * Determine overheads.
 144          * XXX this needs to be repeated for each useful timer/counter.
 145          */
 146         cputime_overhead = 0;
 147         startguprof(p);
 148         for (i = 0; i < CALIB_SCALE; i++)
 149                 cputime_overhead += cputime();
 150
 151         empty_loop();
 152         startguprof(p);
 153         empty_loop();
 154         empty_loop_time = cputime();
 155
 156         nullfunc_loop_profiled();
 157
 158         /*
 159          * Start profiling.  There won't be any normal function calls since
 160          * interrupts are disabled, but we will call the profiling routines
 161          * directly to determine their overheads.
 162          */
 163         p->state = GMON_PROF_HIRES;
 164
 165         startguprof(p);
 166         nullfunc_loop_profiled();
 167
 168         startguprof(p);
 169         for (i = 0; i < CALIB_SCALE; i++)
 170 #if defined(__i386__) && __GNUC__ >= 2
 171                 __asm("pushl %0; call __mcount; popl %%ecx"
 172                       :
 173                       : "i" (profil)
 174                       : "ax", "bx", "cx", "dx", "memory");
 175 #else
 176 #error
 177 #endif
 178         mcount_overhead = KCOUNT(p, PC_TO_I(p, profil));
 179
 180         startguprof(p);
 181         for (i = 0; i < CALIB_SCALE; i++)
 182 #if defined(__i386__) && __GNUC__ >= 2
 183                     __asm("call " __XSTRING(HIDENAME(mexitcount)) "; 1:"
 184                           : : : "ax", "bx", "cx", "dx", "memory");
 185         __asm("movl $1b,%0" : "=rm" (tmp_addr));
 186 #else
 187 #error
 188 #endif
 189         mexitcount_overhead = KCOUNT(p, PC_TO_I(p, tmp_addr));
 190
 191         p->state = GMON_PROF_OFF;
 192         stopguprof(p);
 193
 194         cpu_enable_intr();
 195
 196         nullfunc_loop_profiled_time = 0;
 197         for (tmp_addr = (uintfptr_t)nullfunc_loop_profiled;
 198              tmp_addr < (uintfptr_t)nullfunc_loop_profiled_end;
 199              tmp_addr += HISTFRACTION * sizeof(HISTCOUNTER))
 200                 nullfunc_loop_profiled_time += KCOUNT(p, PC_TO_I(p, tmp_addr));
 201 #define CALIB_DOSCALE(count)    (((count) + CALIB_SCALE / 3) / CALIB_SCALE)
 202 #define c2n(count, freq)        ((int)((count) * 1000000000LL / freq))
 203         kprintf("cputime %d, empty_loop %d, nullfunc_loop_profiled %d, mcount %d, mexitcount %d\n",
 204                CALIB_DOSCALE(c2n(cputime_overhead, p->profrate)),
 205                CALIB_DOSCALE(c2n(empty_loop_time, p->profrate)),
 206                CALIB_DOSCALE(c2n(nullfunc_loop_profiled_time, p->profrate)),
 207                CALIB_DOSCALE(c2n(mcount_overhead, p->profrate)),
 208                CALIB_DOSCALE(c2n(mexitcount_overhead, p->profrate)));
 209         cputime_overhead -= empty_loop_time;
 210         mcount_overhead -= empty_loop_time;
 211         mexitcount_overhead -= empty_loop_time;
 212
 213         /*-
 214          * Profiling overheads are determined by the times between the
 215          * following events:
 216          *      MC1: mcount() is called
 217          *      MC2: cputime() (called from mcount()) latches the timer
 218          *      MC3: mcount() completes
 219          *      ME1: mexitcount() is called
 220          *      ME2: cputime() (called from mexitcount()) latches the timer
 221          *      ME3: mexitcount() completes.
 222          * The times between the events vary slightly depending on instruction
 223          * combination and cache misses, etc.  Attempt to determine the
 224          * minimum times.  These can be subtracted from the profiling times
 225          * without much risk of reducing the profiling times below what they
 226          * would be when profiling is not configured.  Abbreviate:
 227          *      ab = minimum time between MC1 and MC3
 228          *      a  = minumum time between MC1 and MC2
 229          *      b  = minimum time between MC2 and MC3
 230          *      cd = minimum time between ME1 and ME3
 231          *      c  = minimum time between ME1 and ME2
 232          *      d  = minimum time between ME2 and ME3.
 233          * These satisfy the relations:
 234          *      ab            <= mcount_overhead                (just measured)
 235          *      a + b         <= ab
 236          *              cd    <= mexitcount_overhead            (just measured)
 237          *              c + d <= cd
 238          *      a         + d <= nullfunc_loop_profiled_time    (just measured)
 239          *      a >= 0, b >= 0, c >= 0, d >= 0.
 240          * Assume that ab and cd are equal to the minimums.
 241          */
 242         p->cputime_overhead = CALIB_DOSCALE(cputime_overhead);
 243         p->mcount_overhead = CALIB_DOSCALE(mcount_overhead - cputime_overhead);
 244         p->mexitcount_overhead = CALIB_DOSCALE(mexitcount_overhead
 245                                                - cputime_overhead);
 246         nullfunc_loop_overhead = nullfunc_loop_profiled_time - empty_loop_time;
 247         p->mexitcount_post_overhead = CALIB_DOSCALE((mcount_overhead
 248                                                      - nullfunc_loop_overhead)
 249                                                     / 4);
 250         p->mexitcount_pre_overhead = p->mexitcount_overhead
 251                                      + p->cputime_overhead
 252                                      - p->mexitcount_post_overhead;
 253         p->mcount_pre_overhead = CALIB_DOSCALE(nullfunc_loop_overhead)
 254                                  - p->mexitcount_post_overhead;
 255         p->mcount_post_overhead = p->mcount_overhead
 256                                   + p->cputime_overhead
 257                                   - p->mcount_pre_overhead;
 258         kprintf(
 259 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d nsec\n",
 260                c2n(p->cputime_overhead, p->profrate),
 261                c2n(p->mcount_overhead, p->profrate),
 262                c2n(p->mcount_pre_overhead, p->profrate),
 263                c2n(p->mcount_post_overhead, p->profrate),
 264                c2n(p->cputime_overhead, p->profrate),
 265                c2n(p->mexitcount_overhead, p->profrate),
 266                c2n(p->mexitcount_pre_overhead, p->profrate),
 267                c2n(p->mexitcount_post_overhead, p->profrate));
 268         kprintf(
 269 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d cycles\n",
 270                p->cputime_overhead, p->mcount_overhead,
 271                p->mcount_pre_overhead, p->mcount_post_overhead,
 272                p->cputime_overhead, p->mexitcount_overhead,
 273                p->mexitcount_pre_overhead, p->mexitcount_post_overhead);
 274 #endif /* GUPROF */
 275 }
 276
 277 /*
 278  * Return kernel profiling information.
 279  */
 280 static int
 281 sysctl_kern_prof(SYSCTL_HANDLER_ARGS)
 282 {
 283         int *name = (int *) arg1;
 284         u_int namelen = arg2;
 285         struct gmonparam *gp = &_gmonparam;
 286         int error;
 287         int state;
 288
 289         /* all sysctl names at this level are terminal */
 290         if (namelen != 1)
 291                 return (ENOTDIR);               /* overloaded */
 292
 293         switch (name[0]) {
 294         case GPROF_STATE:
 295                 state = gp->state;
 296                 error = sysctl_handle_int(oidp, &state, 0, req);
 297                 if (error)
 298                         return (error);
 299                 if (!req->newptr)
 300                         return (0);
 301                 if (state == GMON_PROF_OFF) {
 302                         gp->state = state;
 303                         stopprofclock(&proc0);
 304                         stopguprof(gp);
 305                 } else if (state == GMON_PROF_ON) {
 306                         gp->state = GMON_PROF_OFF;
 307                         stopguprof(gp);
 308                         gp->profrate = profhz;
 309                         startprofclock(&proc0);
 310                         gp->state = state;
 311 #ifdef GUPROF
 312                 } else if (state == GMON_PROF_HIRES) {
 313                         gp->state = GMON_PROF_OFF;
 314                         stopprofclock(&proc0);
 315                         startguprof(gp);
 316                         gp->state = state;
 317 #endif
 318                 } else if (state != gp->state)
 319                         return (EINVAL);
 320                 return (0);
 321         case GPROF_COUNT:
 322                 return (sysctl_handle_opaque(oidp,
 323                         gp->kcount, gp->kcountsize, req));
 324         case GPROF_FROMS:
 325                 return (sysctl_handle_opaque(oidp,
 326                         gp->froms, gp->fromssize, req));
 327         case GPROF_TOS:
 328                 return (sysctl_handle_opaque(oidp,
 329                         gp->tos, gp->tossize, req));
 330         case GPROF_GMONPARAM:
 331                 return (sysctl_handle_opaque(oidp, gp, sizeof *gp, req));
 332         default:
 333                 return (EOPNOTSUPP);
 334         }
 335         /* NOTREACHED */
 336 }
 337
 338 SYSCTL_NODE(_kern, KERN_PROF, prof, CTLFLAG_RW, sysctl_kern_prof, "");
 339 #endif /* GPROF */
 340
 341 /*
 342  * Profiling system call.
 343  *
 344  * The scale factor is a fixed point number with 16 bits of fraction, so that
 345  * 1.0 is represented as 0x10000.  A scale factor of 0 turns off profiling.
 346  *
 347  * MPALMOSTSAFE
 348  */
 349 int
 350 sys_profil(struct profil_args *uap)
 351 {
 352         struct proc *p = curproc;
 353         struct uprof *upp;
 354
 355         if (uap->scale > (1 << 16))
 356                 return (EINVAL);
 357         get_mplock();
 358         if (uap->scale == 0) {
 359                 stopprofclock(p);
 360         } else {
 361                 upp = &p->p_prof;
 362
 363                 /* Block profile interrupts while changing state. */
 364                 crit_enter();
 365                 upp->pr_off = uap->offset;
 366                 upp->pr_scale = uap->scale;
 367                 upp->pr_base = uap->samples;
 368                 upp->pr_size = uap->size;
 369                 startprofclock(p);
 370                 crit_exit();
 371         }
 372         rel_mplock();
 373         return (0);
 374 }
 375
 376 /*
 377  * Scale is a fixed-point number with the binary point 16 bits
 378  * into the value, and is <= 1.0.  pc is at most 32 bits, so the
 379  * intermediate result is at most 48 bits.
 380  */
 381 #define PC_TO_INDEX(pc, prof) \
 382         ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \
 383             (u_quad_t)((prof)->pr_scale)) >> 16) & ~1)
 384
 385 /*
 386  * Collect user-level profiling statistics; called on a profiling tick,
 387  * when a process is running in user-mode.  This routine may be called
 388  * from an interrupt context.  We try to update the user profiling buffers
 389  * cheaply with fuswintr() and suswintr().  If that fails, we revert to
 390  * an AST that will vector us to trap() with a context in which copyin
 391  * and copyout will work.  Trap will then call addupc_task().
 392  *
 393  * XXX fuswintr() and suswintr() never worked (always returnde -1), remove
 394  * them.  It's just a bad idea to try to do this from a hard interrupt.
 395  *
 396  * Note that we may (rarely) not get around to the AST soon enough, and
 397  * lose profile ticks when the next tick overwrites this one, but in this
 398  * case the system is overloaded and the profile is probably already
 399  * inaccurate.
 400  */
 401 void
 402 addupc_intr(struct proc *p, u_long pc, u_int ticks)
 403 {
 404         struct uprof *prof;
 405         caddr_t addr;
 406         u_int i;
 407
 408         if (ticks == 0)
 409                 return;
 410         prof = &p->p_prof;
 411         if (pc < prof->pr_off ||
 412             (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
 413                 return;                 /* out of range; ignore */
 414
 415         addr = prof->pr_base + i;
 416         prof->pr_addr = pc;
 417         prof->pr_ticks = ticks;
 418         need_proftick();
 419 }
 420
 421 /*
 422  * Much like before, but we can afford to take faults here.  If the
 423  * update fails, we simply turn off profiling.
 424  */
 425 void
 426 addupc_task(struct proc *p, u_long pc, u_int ticks)
 427 {
 428         struct uprof *prof;
 429         caddr_t addr;
 430         u_int i;
 431         u_short v;
 432
 433         /* Testing P_PROFIL may be unnecessary, but is certainly safe. */
 434         if ((p->p_flag & P_PROFIL) == 0 || ticks == 0)
 435                 return;
 436
 437         prof = &p->p_prof;
 438         if (pc < prof->pr_off ||
 439             (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
 440                 return;
 441
 442         addr = prof->pr_base + i;
 443         if (copyin(addr, (caddr_t)&v, sizeof(v)) == 0) {
 444                 v += ticks;
 445                 if (copyout((caddr_t)&v, addr, sizeof(v)) == 0)
 446                         return;
 447         }
 448         stopprofclock(p);
 449 }