kern_clock.c revision 1.141
1 /* $NetBSD: kern_clock.c,v 1.141 2020/05/08 22:10:09 ad Exp $ */ 2 3 /*- 4 * Copyright (c) 2000, 2004, 2006, 2007, 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, 9 * NASA Ames Research Center. 10 * This code is derived from software contributed to The NetBSD Foundation 11 * by Charles M. Hannum. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 23 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 24 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 25 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 26 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 27 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 28 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 29 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 30 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 31 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 32 * POSSIBILITY OF SUCH DAMAGE. 33 */ 34 35 /*- 36 * Copyright (c) 1982, 1986, 1991, 1993 37 * The Regents of the University of California. All rights reserved. 38 * (c) UNIX System Laboratories, Inc. 39 * All or some portions of this file are derived from material licensed 40 * to the University of California by American Telephone and Telegraph 41 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 42 * the permission of UNIX System Laboratories, Inc. 43 * 44 * Redistribution and use in source and binary forms, with or without 45 * modification, are permitted provided that the following conditions 46 * are met: 47 * 1. Redistributions of source code must retain the above copyright 48 * notice, this list of conditions and the following disclaimer. 49 * 2. Redistributions in binary form must reproduce the above copyright 50 * notice, this list of conditions and the following disclaimer in the 51 * documentation and/or other materials provided with the distribution. 52 * 3. Neither the name of the University nor the names of its contributors 53 * may be used to endorse or promote products derived from this software 54 * without specific prior written permission. 55 * 56 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 57 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 58 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 59 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 60 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 61 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 62 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 63 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 64 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 65 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 66 * SUCH DAMAGE. 67 * 68 * @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 69 */ 70 71 #include <sys/cdefs.h> 72 __KERNEL_RCSID(0, "$NetBSD: kern_clock.c,v 1.141 2020/05/08 22:10:09 ad Exp $"); 73 74 #ifdef _KERNEL_OPT 75 #include "opt_dtrace.h" 76 #include "opt_gprof.h" 77 #endif 78 79 #include <sys/param.h> 80 #include <sys/systm.h> 81 #include <sys/callout.h> 82 #include <sys/kernel.h> 83 #include <sys/proc.h> 84 #include <sys/resourcevar.h> 85 #include <sys/signalvar.h> 86 #include <sys/sysctl.h> 87 #include <sys/timex.h> 88 #include <sys/sched.h> 89 #include <sys/time.h> 90 #include <sys/timetc.h> 91 #include <sys/cpu.h> 92 #include <sys/atomic.h> 93 94 #ifdef GPROF 95 #include <sys/gmon.h> 96 #endif 97 98 #ifdef KDTRACE_HOOKS 99 #include <sys/dtrace_bsd.h> 100 #include <sys/cpu.h> 101 102 cyclic_clock_func_t cyclic_clock_func[MAXCPUS]; 103 #endif 104 105 static int sysctl_kern_clockrate(SYSCTLFN_PROTO); 106 107 /* 108 * Clock handling routines. 109 * 110 * This code is written to operate with two timers that run independently of 111 * each other. The main clock, running hz times per second, is used to keep 112 * track of real time. The second timer handles kernel and user profiling, 113 * and does resource use estimation. If the second timer is programmable, 114 * it is randomized to avoid aliasing between the two clocks. For example, 115 * the randomization prevents an adversary from always giving up the CPU 116 * just before its quantum expires. Otherwise, it would never accumulate 117 * CPU ticks. The mean frequency of the second timer is stathz. 118 * 119 * If no second timer exists, stathz will be zero; in this case we drive 120 * profiling and statistics off the main clock. This WILL NOT be accurate; 121 * do not do it unless absolutely necessary. 122 * 123 * The statistics clock may (or may not) be run at a higher rate while 124 * profiling. This profile clock runs at profhz. We require that profhz 125 * be an integral multiple of stathz. 126 * 127 * If the statistics clock is running fast, it must be divided by the ratio 128 * profhz/stathz for statistics. (For profiling, every tick counts.) 129 */ 130 131 int stathz; 132 int profhz; 133 int profsrc; 134 int schedhz; 135 int profprocs; 136 int hardclock_ticks; 137 static int hardscheddiv; /* hard => sched divider (used if schedhz == 0) */ 138 static int psdiv; /* prof => stat divider */ 139 int psratio; /* ratio: prof / stat */ 140 141 static u_int get_intr_timecount(struct timecounter *); 142 143 static struct timecounter intr_timecounter = { 144 .tc_get_timecount = get_intr_timecount, 145 .tc_poll_pps = NULL, 146 .tc_counter_mask = ~0u, 147 .tc_frequency = 0, 148 .tc_name = "clockinterrupt", 149 /* quality - minimum implementation level for a clock */ 150 .tc_quality = 0, 151 .tc_priv = NULL, 152 }; 153 154 static u_int 155 get_intr_timecount(struct timecounter *tc) 156 { 157 158 return (u_int)getticks(); 159 } 160 161 int 162 getticks(void) 163 { 164 return atomic_load_relaxed(&hardclock_ticks); 165 } 166 167 /* 168 * Initialize clock frequencies and start both clocks running. 169 */ 170 void 171 initclocks(void) 172 { 173 static struct sysctllog *clog; 174 int i; 175 176 /* 177 * Set divisors to 1 (normal case) and let the machine-specific 178 * code do its bit. 179 */ 180 psdiv = 1; 181 /* 182 * provide minimum default time counter 183 * will only run at interrupt resolution 184 */ 185 intr_timecounter.tc_frequency = hz; 186 tc_init(&intr_timecounter); 187 cpu_initclocks(); 188 189 /* 190 * Compute profhz and stathz, fix profhz if needed. 191 */ 192 i = stathz ? stathz : hz; 193 if (profhz == 0) 194 profhz = i; 195 psratio = profhz / i; 196 if (schedhz == 0) { 197 /* 16Hz is best */ 198 hardscheddiv = hz / 16; 199 if (hardscheddiv <= 0) 200 panic("hardscheddiv"); 201 } 202 203 sysctl_createv(&clog, 0, NULL, NULL, 204 CTLFLAG_PERMANENT, 205 CTLTYPE_STRUCT, "clockrate", 206 SYSCTL_DESCR("Kernel clock rates"), 207 sysctl_kern_clockrate, 0, NULL, 208 sizeof(struct clockinfo), 209 CTL_KERN, KERN_CLOCKRATE, CTL_EOL); 210 sysctl_createv(&clog, 0, NULL, NULL, 211 CTLFLAG_PERMANENT, 212 CTLTYPE_INT, "hardclock_ticks", 213 SYSCTL_DESCR("Number of hardclock ticks"), 214 NULL, 0, &hardclock_ticks, sizeof(hardclock_ticks), 215 CTL_KERN, KERN_HARDCLOCK_TICKS, CTL_EOL); 216 } 217 218 /* 219 * The real-time timer, interrupting hz times per second. 220 */ 221 void 222 hardclock(struct clockframe *frame) 223 { 224 struct lwp *l; 225 struct cpu_info *ci; 226 227 ci = curcpu(); 228 l = ci->ci_onproc; 229 230 timer_tick(l, CLKF_USERMODE(frame)); 231 232 /* 233 * If no separate statistics clock is available, run it from here. 234 */ 235 if (stathz == 0) 236 statclock(frame); 237 /* 238 * If no separate schedclock is provided, call it here 239 * at about 16 Hz. 240 */ 241 if (schedhz == 0) { 242 if ((int)(--ci->ci_schedstate.spc_schedticks) <= 0) { 243 schedclock(l); 244 ci->ci_schedstate.spc_schedticks = hardscheddiv; 245 } 246 } 247 if ((--ci->ci_schedstate.spc_ticks) <= 0) 248 sched_tick(ci); 249 250 if (CPU_IS_PRIMARY(ci)) { 251 atomic_store_relaxed(&hardclock_ticks, 252 atomic_load_relaxed(&hardclock_ticks) + 1); 253 tc_ticktock(); 254 } 255 256 /* 257 * Update real-time timeout queue. 258 */ 259 callout_hardclock(); 260 } 261 262 /* 263 * Start profiling on a process. 264 * 265 * Kernel profiling passes proc0 which never exits and hence 266 * keeps the profile clock running constantly. 267 */ 268 void 269 startprofclock(struct proc *p) 270 { 271 272 KASSERT(mutex_owned(&p->p_stmutex)); 273 274 if ((p->p_stflag & PST_PROFIL) == 0) { 275 p->p_stflag |= PST_PROFIL; 276 /* 277 * This is only necessary if using the clock as the 278 * profiling source. 279 */ 280 if (++profprocs == 1 && stathz != 0) 281 psdiv = psratio; 282 } 283 } 284 285 /* 286 * Stop profiling on a process. 287 */ 288 void 289 stopprofclock(struct proc *p) 290 { 291 292 KASSERT(mutex_owned(&p->p_stmutex)); 293 294 if (p->p_stflag & PST_PROFIL) { 295 p->p_stflag &= ~PST_PROFIL; 296 /* 297 * This is only necessary if using the clock as the 298 * profiling source. 299 */ 300 if (--profprocs == 0 && stathz != 0) 301 psdiv = 1; 302 } 303 } 304 305 void 306 schedclock(struct lwp *l) 307 { 308 if ((l->l_flag & LW_IDLE) != 0) 309 return; 310 311 sched_schedclock(l); 312 } 313 314 /* 315 * Statistics clock. Grab profile sample, and if divider reaches 0, 316 * do process and kernel statistics. 317 */ 318 void 319 statclock(struct clockframe *frame) 320 { 321 #ifdef GPROF 322 struct gmonparam *g; 323 intptr_t i; 324 #endif 325 struct cpu_info *ci = curcpu(); 326 struct schedstate_percpu *spc = &ci->ci_schedstate; 327 struct proc *p; 328 struct lwp *l; 329 330 /* 331 * Notice changes in divisor frequency, and adjust clock 332 * frequency accordingly. 333 */ 334 if (spc->spc_psdiv != psdiv) { 335 spc->spc_psdiv = psdiv; 336 spc->spc_pscnt = psdiv; 337 if (psdiv == 1) { 338 setstatclockrate(stathz); 339 } else { 340 setstatclockrate(profhz); 341 } 342 } 343 l = ci->ci_onproc; 344 if ((l->l_flag & LW_IDLE) != 0) { 345 /* 346 * don't account idle lwps as swapper. 347 */ 348 p = NULL; 349 } else { 350 p = l->l_proc; 351 mutex_spin_enter(&p->p_stmutex); 352 } 353 354 if (CLKF_USERMODE(frame)) { 355 KASSERT(p != NULL); 356 if ((p->p_stflag & PST_PROFIL) && profsrc == PROFSRC_CLOCK) 357 addupc_intr(l, CLKF_PC(frame)); 358 if (--spc->spc_pscnt > 0) { 359 mutex_spin_exit(&p->p_stmutex); 360 return; 361 } 362 363 /* 364 * Came from user mode; CPU was in user state. 365 * If this process is being profiled record the tick. 366 */ 367 p->p_uticks++; 368 if (p->p_nice > NZERO) 369 spc->spc_cp_time[CP_NICE]++; 370 else 371 spc->spc_cp_time[CP_USER]++; 372 } else { 373 #ifdef GPROF 374 /* 375 * Kernel statistics are just like addupc_intr, only easier. 376 */ 377 g = &_gmonparam; 378 if (profsrc == PROFSRC_CLOCK && g->state == GMON_PROF_ON) { 379 i = CLKF_PC(frame) - g->lowpc; 380 if (i < g->textsize) { 381 i /= HISTFRACTION * sizeof(*g->kcount); 382 g->kcount[i]++; 383 } 384 } 385 #endif 386 #ifdef LWP_PC 387 if (p != NULL && profsrc == PROFSRC_CLOCK && 388 (p->p_stflag & PST_PROFIL)) { 389 addupc_intr(l, LWP_PC(l)); 390 } 391 #endif 392 if (--spc->spc_pscnt > 0) { 393 if (p != NULL) 394 mutex_spin_exit(&p->p_stmutex); 395 return; 396 } 397 /* 398 * Came from kernel mode, so we were: 399 * - handling an interrupt, 400 * - doing syscall or trap work on behalf of the current 401 * user process, or 402 * - spinning in the idle loop. 403 * Whichever it is, charge the time as appropriate. 404 * Note that we charge interrupts to the current process, 405 * regardless of whether they are ``for'' that process, 406 * so that we know how much of its real time was spent 407 * in ``non-process'' (i.e., interrupt) work. 408 */ 409 if (CLKF_INTR(frame) || (curlwp->l_pflag & LP_INTR) != 0) { 410 if (p != NULL) { 411 p->p_iticks++; 412 } 413 spc->spc_cp_time[CP_INTR]++; 414 } else if (p != NULL) { 415 p->p_sticks++; 416 spc->spc_cp_time[CP_SYS]++; 417 } else { 418 spc->spc_cp_time[CP_IDLE]++; 419 } 420 } 421 spc->spc_pscnt = psdiv; 422 423 if (p != NULL) { 424 atomic_inc_uint(&l->l_cpticks); 425 mutex_spin_exit(&p->p_stmutex); 426 } 427 428 #ifdef KDTRACE_HOOKS 429 cyclic_clock_func_t func = cyclic_clock_func[cpu_index(ci)]; 430 if (func) { 431 (*func)((struct clockframe *)frame); 432 } 433 #endif 434 } 435 436 /* 437 * sysctl helper routine for kern.clockrate. Assembles a struct on 438 * the fly to be returned to the caller. 439 */ 440 static int 441 sysctl_kern_clockrate(SYSCTLFN_ARGS) 442 { 443 struct clockinfo clkinfo; 444 struct sysctlnode node; 445 446 clkinfo.tick = tick; 447 clkinfo.tickadj = tickadj; 448 clkinfo.hz = hz; 449 clkinfo.profhz = profhz; 450 clkinfo.stathz = stathz ? stathz : hz; 451 452 node = *rnode; 453 node.sysctl_data = &clkinfo; 454 return (sysctl_lookup(SYSCTLFN_CALL(&node))); 455 } 456
Indexes created Thu Sep 25 08:09:54 GMT 2025