The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_clocksource.c

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    1 /*-
    2  * Copyright (c) 2010-2013 Alexander Motin <mav@FreeBSD.org>
    3  * 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  *    without modification, immediately at the beginning of the file.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD$");
   29 
   30 /*
   31  * Common routines to manage event timers hardware.
   32  */
   33 
   34 #include "opt_device_polling.h"
   35 
   36 #include <sys/param.h>
   37 #include <sys/systm.h>
   38 #include <sys/bus.h>
   39 #include <sys/limits.h>
   40 #include <sys/lock.h>
   41 #include <sys/kdb.h>
   42 #include <sys/ktr.h>
   43 #include <sys/mutex.h>
   44 #include <sys/proc.h>
   45 #include <sys/kernel.h>
   46 #include <sys/sched.h>
   47 #include <sys/smp.h>
   48 #include <sys/sysctl.h>
   49 #include <sys/timeet.h>
   50 #include <sys/timetc.h>
   51 
   52 #include <machine/atomic.h>
   53 #include <machine/clock.h>
   54 #include <machine/cpu.h>
   55 #include <machine/smp.h>
   56 
   57 int                     cpu_disable_c2_sleep = 0; /* Timer dies in C2. */
   58 int                     cpu_disable_c3_sleep = 0; /* Timer dies in C3. */
   59 
   60 static void             setuptimer(void);
   61 static void             loadtimer(sbintime_t now, int first);
   62 static int              doconfigtimer(void);
   63 static void             configtimer(int start);
   64 static int              round_freq(struct eventtimer *et, int freq);
   65 
   66 static sbintime_t       getnextcpuevent(int idle);
   67 static sbintime_t       getnextevent(void);
   68 static int              handleevents(sbintime_t now, int fake);
   69 
   70 static struct mtx       et_hw_mtx;
   71 
   72 #define ET_HW_LOCK(state)                                               \
   73         {                                                               \
   74                 if (timer->et_flags & ET_FLAGS_PERCPU)                  \
   75                         mtx_lock_spin(&(state)->et_hw_mtx);             \
   76                 else                                                    \
   77                         mtx_lock_spin(&et_hw_mtx);                      \
   78         }
   79 
   80 #define ET_HW_UNLOCK(state)                                             \
   81         {                                                               \
   82                 if (timer->et_flags & ET_FLAGS_PERCPU)                  \
   83                         mtx_unlock_spin(&(state)->et_hw_mtx);           \
   84                 else                                                    \
   85                         mtx_unlock_spin(&et_hw_mtx);                    \
   86         }
   87 
   88 static struct eventtimer *timer = NULL;
   89 static sbintime_t       timerperiod;    /* Timer period for periodic mode. */
   90 static sbintime_t       statperiod;     /* statclock() events period. */
   91 static sbintime_t       profperiod;     /* profclock() events period. */
   92 static sbintime_t       nexttick;       /* Next global timer tick time. */
   93 static u_int            busy = 1;       /* Reconfiguration is in progress. */
   94 static int              profiling;      /* Profiling events enabled. */
   95 
   96 static char             timername[32];  /* Wanted timer. */
   97 TUNABLE_STR("kern.eventtimer.timer", timername, sizeof(timername));
   98 
   99 static int              singlemul;      /* Multiplier for periodic mode. */
  100 SYSCTL_INT(_kern_eventtimer, OID_AUTO, singlemul, CTLFLAG_RWTUN, &singlemul,
  101     0, "Multiplier for periodic mode");
  102 
  103 static u_int            idletick;       /* Run periodic events when idle. */
  104 SYSCTL_UINT(_kern_eventtimer, OID_AUTO, idletick, CTLFLAG_RWTUN, &idletick,
  105     0, "Run periodic events when idle");
  106 
  107 static int              periodic;       /* Periodic or one-shot mode. */
  108 static int              want_periodic;  /* What mode to prefer. */
  109 TUNABLE_INT("kern.eventtimer.periodic", &want_periodic);
  110 
  111 struct pcpu_state {
  112         struct mtx      et_hw_mtx;      /* Per-CPU timer mutex. */
  113         u_int           action;         /* Reconfiguration requests. */
  114         u_int           handle;         /* Immediate handle resuests. */
  115         sbintime_t      now;            /* Last tick time. */
  116         sbintime_t      nextevent;      /* Next scheduled event on this CPU. */
  117         sbintime_t      nexttick;       /* Next timer tick time. */
  118         sbintime_t      nexthard;       /* Next hardclock() event. */
  119         sbintime_t      nextstat;       /* Next statclock() event. */
  120         sbintime_t      nextprof;       /* Next profclock() event. */
  121         sbintime_t      nextcall;       /* Next callout event. */
  122         sbintime_t      nextcallopt;    /* Next optional callout event. */
  123         int             ipi;            /* This CPU needs IPI. */
  124         int             idle;           /* This CPU is in idle mode. */
  125 };
  126 
  127 static DPCPU_DEFINE(struct pcpu_state, timerstate);
  128 DPCPU_DEFINE(sbintime_t, hardclocktime);
  129 
  130 /*
  131  * Timer broadcast IPI handler.
  132  */
  133 int
  134 hardclockintr(void)
  135 {
  136         sbintime_t now;
  137         struct pcpu_state *state;
  138         int done;
  139 
  140         if (doconfigtimer() || busy)
  141                 return (FILTER_HANDLED);
  142         state = DPCPU_PTR(timerstate);
  143         now = state->now;
  144         CTR3(KTR_SPARE2, "ipi  at %d:    now  %d.%08x",
  145             curcpu, (int)(now >> 32), (u_int)(now & 0xffffffff));
  146         done = handleevents(now, 0);
  147         return (done ? FILTER_HANDLED : FILTER_STRAY);
  148 }
  149 
  150 /*
  151  * Handle all events for specified time on this CPU
  152  */
  153 static int
  154 handleevents(sbintime_t now, int fake)
  155 {
  156         sbintime_t t, *hct;
  157         struct trapframe *frame;
  158         struct pcpu_state *state;
  159         int usermode;
  160         int done, runs;
  161 
  162         CTR3(KTR_SPARE2, "handle at %d:  now  %d.%08x",
  163             curcpu, (int)(now >> 32), (u_int)(now & 0xffffffff));
  164         done = 0;
  165         if (fake) {
  166                 frame = NULL;
  167                 usermode = 0;
  168         } else {
  169                 frame = curthread->td_intr_frame;
  170                 usermode = TRAPF_USERMODE(frame);
  171         }
  172 
  173         state = DPCPU_PTR(timerstate);
  174 
  175         runs = 0;
  176         while (now >= state->nexthard) {
  177                 state->nexthard += tick_sbt;
  178                 runs++;
  179         }
  180         if (runs) {
  181                 hct = DPCPU_PTR(hardclocktime);
  182                 *hct = state->nexthard - tick_sbt;
  183                 if (fake < 2) {
  184                         hardclock_cnt(runs, usermode);
  185                         done = 1;
  186                 }
  187         }
  188         runs = 0;
  189         while (now >= state->nextstat) {
  190                 state->nextstat += statperiod;
  191                 runs++;
  192         }
  193         if (runs && fake < 2) {
  194                 statclock_cnt(runs, usermode);
  195                 done = 1;
  196         }
  197         if (profiling) {
  198                 runs = 0;
  199                 while (now >= state->nextprof) {
  200                         state->nextprof += profperiod;
  201                         runs++;
  202                 }
  203                 if (runs && !fake) {
  204                         profclock_cnt(runs, usermode, TRAPF_PC(frame));
  205                         done = 1;
  206                 }
  207         } else
  208                 state->nextprof = state->nextstat;
  209         if (now >= state->nextcallopt || now >= state->nextcall) {
  210                 state->nextcall = state->nextcallopt = SBT_MAX;
  211                 callout_process(now);
  212         }
  213 
  214         t = getnextcpuevent(0);
  215         ET_HW_LOCK(state);
  216         if (!busy) {
  217                 state->idle = 0;
  218                 state->nextevent = t;
  219                 loadtimer(now, (fake == 2) &&
  220                     (timer->et_flags & ET_FLAGS_PERCPU));
  221         }
  222         ET_HW_UNLOCK(state);
  223         return (done);
  224 }
  225 
  226 /*
  227  * Schedule binuptime of the next event on current CPU.
  228  */
  229 static sbintime_t
  230 getnextcpuevent(int idle)
  231 {
  232         sbintime_t event;
  233         struct pcpu_state *state;
  234         u_int hardfreq;
  235 
  236         state = DPCPU_PTR(timerstate);
  237         /* Handle hardclock() events, skipping some if CPU is idle. */
  238         event = state->nexthard;
  239         if (idle) {
  240                 hardfreq = (u_int)hz / 2;
  241                 if (tc_min_ticktock_freq > 2
  242 #ifdef SMP
  243                     && curcpu == CPU_FIRST()
  244 #endif
  245                     )
  246                         hardfreq = hz / tc_min_ticktock_freq;
  247                 if (hardfreq > 1)
  248                         event += tick_sbt * (hardfreq - 1);
  249         }
  250         /* Handle callout events. */
  251         if (event > state->nextcall)
  252                 event = state->nextcall;
  253         if (!idle) { /* If CPU is active - handle other types of events. */
  254                 if (event > state->nextstat)
  255                         event = state->nextstat;
  256                 if (profiling && event > state->nextprof)
  257                         event = state->nextprof;
  258         }
  259         return (event);
  260 }
  261 
  262 /*
  263  * Schedule binuptime of the next event on all CPUs.
  264  */
  265 static sbintime_t
  266 getnextevent(void)
  267 {
  268         struct pcpu_state *state;
  269         sbintime_t event;
  270 #ifdef SMP
  271         int     cpu;
  272 #endif
  273 #ifdef KTR
  274         int     c;
  275 
  276         c = -1;
  277 #endif
  278         state = DPCPU_PTR(timerstate);
  279         event = state->nextevent;
  280 #ifdef SMP
  281         if ((timer->et_flags & ET_FLAGS_PERCPU) == 0) {
  282                 CPU_FOREACH(cpu) {
  283                         state = DPCPU_ID_PTR(cpu, timerstate);
  284                         if (event > state->nextevent) {
  285                                 event = state->nextevent;
  286 #ifdef KTR
  287                                 c = cpu;
  288 #endif
  289                         }
  290                 }
  291         }
  292 #endif
  293         CTR4(KTR_SPARE2, "next at %d:    next %d.%08x by %d",
  294             curcpu, (int)(event >> 32), (u_int)(event & 0xffffffff), c);
  295         return (event);
  296 }
  297 
  298 /* Hardware timer callback function. */
  299 static void
  300 timercb(struct eventtimer *et, void *arg)
  301 {
  302         sbintime_t now;
  303         sbintime_t *next;
  304         struct pcpu_state *state;
  305 #ifdef SMP
  306         int cpu, bcast;
  307 #endif
  308 
  309         /* Do not touch anything if somebody reconfiguring timers. */
  310         if (busy)
  311                 return;
  312         /* Update present and next tick times. */
  313         state = DPCPU_PTR(timerstate);
  314         if (et->et_flags & ET_FLAGS_PERCPU) {
  315                 next = &state->nexttick;
  316         } else
  317                 next = &nexttick;
  318         now = sbinuptime();
  319         if (periodic)
  320                 *next = now + timerperiod;
  321         else
  322                 *next = -1;     /* Next tick is not scheduled yet. */
  323         state->now = now;
  324         CTR3(KTR_SPARE2, "intr at %d:    now  %d.%08x",
  325             curcpu, (int)(now >> 32), (u_int)(now & 0xffffffff));
  326 
  327 #ifdef SMP
  328 #ifdef EARLY_AP_STARTUP
  329         MPASS(mp_ncpus == 1 || smp_started);
  330 #endif
  331         /* Prepare broadcasting to other CPUs for non-per-CPU timers. */
  332         bcast = 0;
  333 #ifdef EARLY_AP_STARTUP
  334         if ((et->et_flags & ET_FLAGS_PERCPU) == 0) {
  335 #else
  336         if ((et->et_flags & ET_FLAGS_PERCPU) == 0 && smp_started) {
  337 #endif
  338                 CPU_FOREACH(cpu) {
  339                         state = DPCPU_ID_PTR(cpu, timerstate);
  340                         ET_HW_LOCK(state);
  341                         state->now = now;
  342                         if (now >= state->nextevent) {
  343                                 state->nextevent += SBT_1S;
  344                                 if (curcpu != cpu) {
  345                                         state->ipi = 1;
  346                                         bcast = 1;
  347                                 }
  348                         }
  349                         ET_HW_UNLOCK(state);
  350                 }
  351         }
  352 #endif
  353 
  354         /* Handle events for this time on this CPU. */
  355         handleevents(now, 0);
  356 
  357 #ifdef SMP
  358         /* Broadcast interrupt to other CPUs for non-per-CPU timers. */
  359         if (bcast) {
  360                 CPU_FOREACH(cpu) {
  361                         if (curcpu == cpu)
  362                                 continue;
  363                         state = DPCPU_ID_PTR(cpu, timerstate);
  364                         if (state->ipi) {
  365                                 state->ipi = 0;
  366                                 ipi_cpu(cpu, IPI_HARDCLOCK);
  367                         }
  368                 }
  369         }
  370 #endif
  371 }
  372 
  373 /*
  374  * Load new value into hardware timer.
  375  */
  376 static void
  377 loadtimer(sbintime_t now, int start)
  378 {
  379         struct pcpu_state *state;
  380         sbintime_t new;
  381         sbintime_t *next;
  382         uint64_t tmp;
  383         int eq;
  384 
  385         if (timer->et_flags & ET_FLAGS_PERCPU) {
  386                 state = DPCPU_PTR(timerstate);
  387                 next = &state->nexttick;
  388         } else
  389                 next = &nexttick;
  390         if (periodic) {
  391                 if (start) {
  392                         /*
  393                          * Try to start all periodic timers aligned
  394                          * to period to make events synchronous.
  395                          */
  396                         tmp = now % timerperiod;
  397                         new = timerperiod - tmp;
  398                         if (new < tmp)          /* Left less then passed. */
  399                                 new += timerperiod;
  400                         CTR5(KTR_SPARE2, "load p at %d:   now %d.%08x first in %d.%08x",
  401                             curcpu, (int)(now >> 32), (u_int)(now & 0xffffffff),
  402                             (int)(new >> 32), (u_int)(new & 0xffffffff));
  403                         *next = new + now;
  404                         et_start(timer, new, timerperiod);
  405                 }
  406         } else {
  407                 new = getnextevent();
  408                 eq = (new == *next);
  409                 CTR4(KTR_SPARE2, "load at %d:    next %d.%08x eq %d",
  410                     curcpu, (int)(new >> 32), (u_int)(new & 0xffffffff), eq);
  411                 if (!eq) {
  412                         *next = new;
  413                         et_start(timer, new - now, 0);
  414                 }
  415         }
  416 }
  417 
  418 /*
  419  * Prepare event timer parameters after configuration changes.
  420  */
  421 static void
  422 setuptimer(void)
  423 {
  424         int freq;
  425 
  426         if (periodic && (timer->et_flags & ET_FLAGS_PERIODIC) == 0)
  427                 periodic = 0;
  428         else if (!periodic && (timer->et_flags & ET_FLAGS_ONESHOT) == 0)
  429                 periodic = 1;
  430         singlemul = MIN(MAX(singlemul, 1), 20);
  431         freq = hz * singlemul;
  432         while (freq < (profiling ? profhz : stathz))
  433                 freq += hz;
  434         freq = round_freq(timer, freq);
  435         timerperiod = SBT_1S / freq;
  436 }
  437 
  438 /*
  439  * Reconfigure specified per-CPU timer on other CPU. Called from IPI handler.
  440  */
  441 static int
  442 doconfigtimer(void)
  443 {
  444         sbintime_t now;
  445         struct pcpu_state *state;
  446 
  447         state = DPCPU_PTR(timerstate);
  448         switch (atomic_load_acq_int(&state->action)) {
  449         case 1:
  450                 now = sbinuptime();
  451                 ET_HW_LOCK(state);
  452                 loadtimer(now, 1);
  453                 ET_HW_UNLOCK(state);
  454                 state->handle = 0;
  455                 atomic_store_rel_int(&state->action, 0);
  456                 return (1);
  457         case 2:
  458                 ET_HW_LOCK(state);
  459                 et_stop(timer);
  460                 ET_HW_UNLOCK(state);
  461                 state->handle = 0;
  462                 atomic_store_rel_int(&state->action, 0);
  463                 return (1);
  464         }
  465         if (atomic_readandclear_int(&state->handle) && !busy) {
  466                 now = sbinuptime();
  467                 handleevents(now, 0);
  468                 return (1);
  469         }
  470         return (0);
  471 }
  472 
  473 /*
  474  * Reconfigure specified timer.
  475  * For per-CPU timers use IPI to make other CPUs to reconfigure.
  476  */
  477 static void
  478 configtimer(int start)
  479 {
  480         sbintime_t now, next;
  481         struct pcpu_state *state;
  482         int cpu;
  483 
  484         if (start) {
  485                 setuptimer();
  486                 now = sbinuptime();
  487         } else
  488                 now = 0;
  489         critical_enter();
  490         ET_HW_LOCK(DPCPU_PTR(timerstate));
  491         if (start) {
  492                 /* Initialize time machine parameters. */
  493                 next = now + timerperiod;
  494                 if (periodic)
  495                         nexttick = next;
  496                 else
  497                         nexttick = -1;
  498 #ifdef EARLY_AP_STARTUP
  499                 MPASS(mp_ncpus == 1 || smp_started);
  500 #endif
  501                 CPU_FOREACH(cpu) {
  502                         state = DPCPU_ID_PTR(cpu, timerstate);
  503                         state->now = now;
  504 #ifndef EARLY_AP_STARTUP
  505                         if (!smp_started && cpu != CPU_FIRST())
  506                                 state->nextevent = SBT_MAX;
  507                         else
  508 #endif
  509                                 state->nextevent = next;
  510                         if (periodic)
  511                                 state->nexttick = next;
  512                         else
  513                                 state->nexttick = -1;
  514                         state->nexthard = next;
  515                         state->nextstat = next;
  516                         state->nextprof = next;
  517                         state->nextcall = next;
  518                         state->nextcallopt = next;
  519                         hardclock_sync(cpu);
  520                 }
  521                 busy = 0;
  522                 /* Start global timer or per-CPU timer of this CPU. */
  523                 loadtimer(now, 1);
  524         } else {
  525                 busy = 1;
  526                 /* Stop global timer or per-CPU timer of this CPU. */
  527                 et_stop(timer);
  528         }
  529         ET_HW_UNLOCK(DPCPU_PTR(timerstate));
  530 #ifdef SMP
  531 #ifdef EARLY_AP_STARTUP
  532         /* If timer is global we are done. */
  533         if ((timer->et_flags & ET_FLAGS_PERCPU) == 0) {
  534 #else
  535         /* If timer is global or there is no other CPUs yet - we are done. */
  536         if ((timer->et_flags & ET_FLAGS_PERCPU) == 0 || !smp_started) {
  537 #endif
  538                 critical_exit();
  539                 return;
  540         }
  541         /* Set reconfigure flags for other CPUs. */
  542         CPU_FOREACH(cpu) {
  543                 state = DPCPU_ID_PTR(cpu, timerstate);
  544                 atomic_store_rel_int(&state->action,
  545                     (cpu == curcpu) ? 0 : ( start ? 1 : 2));
  546         }
  547         /* Broadcast reconfigure IPI. */
  548         ipi_all_but_self(IPI_HARDCLOCK);
  549         /* Wait for reconfiguration completed. */
  550 restart:
  551         cpu_spinwait();
  552         CPU_FOREACH(cpu) {
  553                 if (cpu == curcpu)
  554                         continue;
  555                 state = DPCPU_ID_PTR(cpu, timerstate);
  556                 if (atomic_load_acq_int(&state->action))
  557                         goto restart;
  558         }
  559 #endif
  560         critical_exit();
  561 }
  562 
  563 /*
  564  * Calculate nearest frequency supported by hardware timer.
  565  */
  566 static int
  567 round_freq(struct eventtimer *et, int freq)
  568 {
  569         uint64_t div;
  570 
  571         if (et->et_frequency != 0) {
  572                 div = lmax((et->et_frequency + freq / 2) / freq, 1);
  573                 if (et->et_flags & ET_FLAGS_POW2DIV)
  574                         div = 1 << (flsl(div + div / 2) - 1);
  575                 freq = (et->et_frequency + div / 2) / div;
  576         }
  577         if (et->et_min_period > SBT_1S)
  578                 panic("Event timer \"%s\" doesn't support sub-second periods!",
  579                     et->et_name);
  580         else if (et->et_min_period != 0)
  581                 freq = min(freq, SBT2FREQ(et->et_min_period));
  582         if (et->et_max_period < SBT_1S && et->et_max_period != 0)
  583                 freq = max(freq, SBT2FREQ(et->et_max_period));
  584         return (freq);
  585 }
  586 
  587 /*
  588  * Configure and start event timers (BSP part).
  589  */
  590 void
  591 cpu_initclocks_bsp(void)
  592 {
  593         struct pcpu_state *state;
  594         int base, div, cpu;
  595 
  596         mtx_init(&et_hw_mtx, "et_hw_mtx", NULL, MTX_SPIN);
  597         CPU_FOREACH(cpu) {
  598                 state = DPCPU_ID_PTR(cpu, timerstate);
  599                 mtx_init(&state->et_hw_mtx, "et_hw_mtx", NULL, MTX_SPIN);
  600                 state->nextcall = SBT_MAX;
  601                 state->nextcallopt = SBT_MAX;
  602         }
  603         periodic = want_periodic;
  604         /* Grab requested timer or the best of present. */
  605         if (timername[0])
  606                 timer = et_find(timername, 0, 0);
  607         if (timer == NULL && periodic) {
  608                 timer = et_find(NULL,
  609                     ET_FLAGS_PERIODIC, ET_FLAGS_PERIODIC);
  610         }
  611         if (timer == NULL) {
  612                 timer = et_find(NULL,
  613                     ET_FLAGS_ONESHOT, ET_FLAGS_ONESHOT);
  614         }
  615         if (timer == NULL && !periodic) {
  616                 timer = et_find(NULL,
  617                     ET_FLAGS_PERIODIC, ET_FLAGS_PERIODIC);
  618         }
  619         if (timer == NULL)
  620                 panic("No usable event timer found!");
  621         et_init(timer, timercb, NULL, NULL);
  622 
  623         /* Adapt to timer capabilities. */
  624         if (periodic && (timer->et_flags & ET_FLAGS_PERIODIC) == 0)
  625                 periodic = 0;
  626         else if (!periodic && (timer->et_flags & ET_FLAGS_ONESHOT) == 0)
  627                 periodic = 1;
  628         if (timer->et_flags & ET_FLAGS_C3STOP)
  629                 cpu_disable_c3_sleep++;
  630 
  631         /*
  632          * We honor the requested 'hz' value.
  633          * We want to run stathz in the neighborhood of 128hz.
  634          * We would like profhz to run as often as possible.
  635          */
  636         if (singlemul <= 0 || singlemul > 20) {
  637                 if (hz >= 1500 || (hz % 128) == 0)
  638                         singlemul = 1;
  639                 else if (hz >= 750)
  640                         singlemul = 2;
  641                 else
  642                         singlemul = 4;
  643         }
  644         if (periodic) {
  645                 base = round_freq(timer, hz * singlemul);
  646                 singlemul = max((base + hz / 2) / hz, 1);
  647                 hz = (base + singlemul / 2) / singlemul;
  648                 if (base <= 128)
  649                         stathz = base;
  650                 else {
  651                         div = base / 128;
  652                         if (div >= singlemul && (div % singlemul) == 0)
  653                                 div++;
  654                         stathz = base / div;
  655                 }
  656                 profhz = stathz;
  657                 while ((profhz + stathz) <= 128 * 64)
  658                         profhz += stathz;
  659                 profhz = round_freq(timer, profhz);
  660         } else {
  661                 hz = round_freq(timer, hz);
  662                 stathz = round_freq(timer, 127);
  663                 profhz = round_freq(timer, stathz * 64);
  664         }
  665         tick = 1000000 / hz;
  666         tick_sbt = SBT_1S / hz;
  667         tick_bt = sbttobt(tick_sbt);
  668         statperiod = SBT_1S / stathz;
  669         profperiod = SBT_1S / profhz;
  670         ET_LOCK();
  671         configtimer(1);
  672         ET_UNLOCK();
  673 }
  674 
  675 /*
  676  * Start per-CPU event timers on APs.
  677  */
  678 void
  679 cpu_initclocks_ap(void)
  680 {
  681         sbintime_t now;
  682         struct pcpu_state *state;
  683         struct thread *td;
  684 
  685         state = DPCPU_PTR(timerstate);
  686         now = sbinuptime();
  687         ET_HW_LOCK(state);
  688         state->now = now;
  689         hardclock_sync(curcpu);
  690         spinlock_enter();
  691         ET_HW_UNLOCK(state);
  692         td = curthread;
  693         td->td_intr_nesting_level++;
  694         handleevents(state->now, 2);
  695         td->td_intr_nesting_level--;
  696         spinlock_exit();
  697 }
  698 
  699 void
  700 suspendclock(void)
  701 {
  702         ET_LOCK();
  703         configtimer(0);
  704         ET_UNLOCK();
  705 }
  706 
  707 void
  708 resumeclock(void)
  709 {
  710         ET_LOCK();
  711         configtimer(1);
  712         ET_UNLOCK();
  713 }
  714 
  715 /*
  716  * Switch to profiling clock rates.
  717  */
  718 void
  719 cpu_startprofclock(void)
  720 {
  721 
  722         ET_LOCK();
  723         if (profiling == 0) {
  724                 if (periodic) {
  725                         configtimer(0);
  726                         profiling = 1;
  727                         configtimer(1);
  728                 } else
  729                         profiling = 1;
  730         } else
  731                 profiling++;
  732         ET_UNLOCK();
  733 }
  734 
  735 /*
  736  * Switch to regular clock rates.
  737  */
  738 void
  739 cpu_stopprofclock(void)
  740 {
  741 
  742         ET_LOCK();
  743         if (profiling == 1) {
  744                 if (periodic) {
  745                         configtimer(0);
  746                         profiling = 0;
  747                         configtimer(1);
  748                 } else
  749                 profiling = 0;
  750         } else
  751                 profiling--;
  752         ET_UNLOCK();
  753 }
  754 
  755 /*
  756  * Switch to idle mode (all ticks handled).
  757  */
  758 sbintime_t
  759 cpu_idleclock(void)
  760 {
  761         sbintime_t now, t;
  762         struct pcpu_state *state;
  763 
  764         if (idletick || busy ||
  765             (periodic && (timer->et_flags & ET_FLAGS_PERCPU))
  766 #ifdef DEVICE_POLLING
  767             || curcpu == CPU_FIRST()
  768 #endif
  769             )
  770                 return (-1);
  771         state = DPCPU_PTR(timerstate);
  772         if (periodic)
  773                 now = state->now;
  774         else
  775                 now = sbinuptime();
  776         CTR3(KTR_SPARE2, "idle at %d:    now  %d.%08x",
  777             curcpu, (int)(now >> 32), (u_int)(now & 0xffffffff));
  778         t = getnextcpuevent(1);
  779         ET_HW_LOCK(state);
  780         state->idle = 1;
  781         state->nextevent = t;
  782         if (!periodic)
  783                 loadtimer(now, 0);
  784         ET_HW_UNLOCK(state);
  785         return (MAX(t - now, 0));
  786 }
  787 
  788 /*
  789  * Switch to active mode (skip empty ticks).
  790  */
  791 void
  792 cpu_activeclock(void)
  793 {
  794         sbintime_t now;
  795         struct pcpu_state *state;
  796         struct thread *td;
  797 
  798         state = DPCPU_PTR(timerstate);
  799         if (state->idle == 0 || busy)
  800                 return;
  801         if (periodic)
  802                 now = state->now;
  803         else
  804                 now = sbinuptime();
  805         CTR3(KTR_SPARE2, "active at %d:  now  %d.%08x",
  806             curcpu, (int)(now >> 32), (u_int)(now & 0xffffffff));
  807         spinlock_enter();
  808         td = curthread;
  809         td->td_intr_nesting_level++;
  810         handleevents(now, 1);
  811         td->td_intr_nesting_level--;
  812         spinlock_exit();
  813 }
  814 
  815 /*
  816  * Change the frequency of the given timer.  This changes et->et_frequency and
  817  * if et is the active timer it reconfigures the timer on all CPUs.  This is
  818  * intended to be a private interface for the use of et_change_frequency() only.
  819  */
  820 void
  821 cpu_et_frequency(struct eventtimer *et, uint64_t newfreq)
  822 {
  823 
  824         ET_LOCK();
  825         if (et == timer) {
  826                 configtimer(0);
  827                 et->et_frequency = newfreq;
  828                 configtimer(1);
  829         } else
  830                 et->et_frequency = newfreq;
  831         ET_UNLOCK();
  832 }
  833 
  834 void
  835 cpu_new_callout(int cpu, sbintime_t bt, sbintime_t bt_opt)
  836 {
  837         struct pcpu_state *state;
  838 
  839         /* Do not touch anything if somebody reconfiguring timers. */
  840         if (busy)
  841                 return;
  842         CTR6(KTR_SPARE2, "new co at %d:    on %d at %d.%08x - %d.%08x",
  843             curcpu, cpu, (int)(bt_opt >> 32), (u_int)(bt_opt & 0xffffffff),
  844             (int)(bt >> 32), (u_int)(bt & 0xffffffff));
  845         state = DPCPU_ID_PTR(cpu, timerstate);
  846         ET_HW_LOCK(state);
  847 
  848         /*
  849          * If there is callout time already set earlier -- do nothing.
  850          * This check may appear redundant because we check already in
  851          * callout_process() but this double check guarantees we're safe
  852          * with respect to race conditions between interrupts execution
  853          * and scheduling.
  854          */
  855         state->nextcallopt = bt_opt;
  856         if (bt >= state->nextcall)
  857                 goto done;
  858         state->nextcall = bt;
  859         /* If there is some other event set earlier -- do nothing. */
  860         if (bt >= state->nextevent)
  861                 goto done;
  862         state->nextevent = bt;
  863         /* If timer is periodic -- there is nothing to reprogram. */
  864         if (periodic)
  865                 goto done;
  866         /* If timer is global or of the current CPU -- reprogram it. */
  867         if ((timer->et_flags & ET_FLAGS_PERCPU) == 0 || cpu == curcpu) {
  868                 loadtimer(sbinuptime(), 0);
  869 done:
  870                 ET_HW_UNLOCK(state);
  871                 return;
  872         }
  873         /* Otherwise make other CPU to reprogram it. */
  874         state->handle = 1;
  875         ET_HW_UNLOCK(state);
  876 #ifdef SMP
  877         ipi_cpu(cpu, IPI_HARDCLOCK);
  878 #endif
  879 }
  880 
  881 /*
  882  * Report or change the active event timers hardware.
  883  */
  884 static int
  885 sysctl_kern_eventtimer_timer(SYSCTL_HANDLER_ARGS)
  886 {
  887         char buf[32];
  888         struct eventtimer *et;
  889         int error;
  890 
  891         ET_LOCK();
  892         et = timer;
  893         snprintf(buf, sizeof(buf), "%s", et->et_name);
  894         ET_UNLOCK();
  895         error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
  896         ET_LOCK();
  897         et = timer;
  898         if (error != 0 || req->newptr == NULL ||
  899             strcasecmp(buf, et->et_name) == 0) {
  900                 ET_UNLOCK();
  901                 return (error);
  902         }
  903         et = et_find(buf, 0, 0);
  904         if (et == NULL) {
  905                 ET_UNLOCK();
  906                 return (ENOENT);
  907         }
  908         configtimer(0);
  909         et_free(timer);
  910         if (et->et_flags & ET_FLAGS_C3STOP)
  911                 cpu_disable_c3_sleep++;
  912         if (timer->et_flags & ET_FLAGS_C3STOP)
  913                 cpu_disable_c3_sleep--;
  914         periodic = want_periodic;
  915         timer = et;
  916         et_init(timer, timercb, NULL, NULL);
  917         configtimer(1);
  918         ET_UNLOCK();
  919         return (error);
  920 }
  921 SYSCTL_PROC(_kern_eventtimer, OID_AUTO, timer,
  922     CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_MPSAFE,
  923     0, 0, sysctl_kern_eventtimer_timer, "A", "Chosen event timer");
  924 
  925 /*
  926  * Report or change the active event timer periodicity.
  927  */
  928 static int
  929 sysctl_kern_eventtimer_periodic(SYSCTL_HANDLER_ARGS)
  930 {
  931         int error, val;
  932 
  933         val = periodic;
  934         error = sysctl_handle_int(oidp, &val, 0, req);
  935         if (error != 0 || req->newptr == NULL)
  936                 return (error);
  937         ET_LOCK();
  938         configtimer(0);
  939         periodic = want_periodic = val;
  940         configtimer(1);
  941         ET_UNLOCK();
  942         return (error);
  943 }
  944 SYSCTL_PROC(_kern_eventtimer, OID_AUTO, periodic,
  945     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
  946     0, 0, sysctl_kern_eventtimer_periodic, "I", "Enable event timer periodic mode");
  947 
  948 #include "opt_ddb.h"
  949 
  950 #ifdef DDB
  951 #include <ddb/ddb.h>
  952 
  953 DB_SHOW_COMMAND(clocksource, db_show_clocksource)
  954 {
  955         struct pcpu_state *st;
  956         int c;
  957 
  958         CPU_FOREACH(c) {
  959                 st = DPCPU_ID_PTR(c, timerstate);
  960                 db_printf(
  961                     "CPU %2d: action %d handle %d  ipi %d idle %d\n"
  962                     "        now %#jx nevent %#jx (%jd)\n"
  963                     "        ntick %#jx (%jd) nhard %#jx (%jd)\n"
  964                     "        nstat %#jx (%jd) nprof %#jx (%jd)\n"
  965                     "        ncall %#jx (%jd) ncallopt %#jx (%jd)\n",
  966                     c, st->action, st->handle, st->ipi, st->idle,
  967                     (uintmax_t)st->now,
  968                     (uintmax_t)st->nextevent,
  969                     (uintmax_t)(st->nextevent - st->now) / tick_sbt,
  970                     (uintmax_t)st->nexttick,
  971                     (uintmax_t)(st->nexttick - st->now) / tick_sbt,
  972                     (uintmax_t)st->nexthard,
  973                     (uintmax_t)(st->nexthard - st->now) / tick_sbt,
  974                     (uintmax_t)st->nextstat,
  975                     (uintmax_t)(st->nextstat - st->now) / tick_sbt,
  976                     (uintmax_t)st->nextprof,
  977                     (uintmax_t)(st->nextprof - st->now) / tick_sbt,
  978                     (uintmax_t)st->nextcall,
  979                     (uintmax_t)(st->nextcall - st->now) / tick_sbt,
  980                     (uintmax_t)st->nextcallopt,
  981                     (uintmax_t)(st->nextcallopt - st->now) / tick_sbt);
  982         }
  983 }
  984 
  985 #endif

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