| 1 | /* $NetBSD: kern_synch.c,v 1.311 2016/07/03 14:24:58 christos Exp $ */ |
| 2 | |
| 3 | /*- |
| 4 | * Copyright (c) 1999, 2000, 2004, 2006, 2007, 2008, 2009 |
| 5 | * The NetBSD Foundation, Inc. |
| 6 | * All rights reserved. |
| 7 | * |
| 8 | * This code is derived from software contributed to The NetBSD Foundation |
| 9 | * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, |
| 10 | * NASA Ames Research Center, by Charles M. Hannum, Andrew Doran and |
| 11 | * Daniel Sieger. |
| 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, 1990, 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_synch.c 8.9 (Berkeley) 5/19/95 |
| 69 | */ |
| 70 | |
| 71 | #include <sys/cdefs.h> |
| 72 | __KERNEL_RCSID(0, "$NetBSD: kern_synch.c,v 1.311 2016/07/03 14:24:58 christos Exp $" ); |
| 73 | |
| 74 | #include "opt_kstack.h" |
| 75 | #include "opt_perfctrs.h" |
| 76 | #include "opt_dtrace.h" |
| 77 | |
| 78 | #define __MUTEX_PRIVATE |
| 79 | |
| 80 | #include <sys/param.h> |
| 81 | #include <sys/systm.h> |
| 82 | #include <sys/proc.h> |
| 83 | #include <sys/kernel.h> |
| 84 | #if defined(PERFCTRS) |
| 85 | #include <sys/pmc.h> |
| 86 | #endif |
| 87 | #include <sys/cpu.h> |
| 88 | #include <sys/pserialize.h> |
| 89 | #include <sys/resourcevar.h> |
| 90 | #include <sys/sched.h> |
| 91 | #include <sys/syscall_stats.h> |
| 92 | #include <sys/sleepq.h> |
| 93 | #include <sys/lockdebug.h> |
| 94 | #include <sys/evcnt.h> |
| 95 | #include <sys/intr.h> |
| 96 | #include <sys/lwpctl.h> |
| 97 | #include <sys/atomic.h> |
| 98 | #include <sys/syslog.h> |
| 99 | |
| 100 | #include <uvm/uvm_extern.h> |
| 101 | |
| 102 | #include <dev/lockstat.h> |
| 103 | |
| 104 | #include <sys/dtrace_bsd.h> |
| 105 | int dtrace_vtime_active=0; |
| 106 | dtrace_vtime_switch_func_t dtrace_vtime_switch_func; |
| 107 | |
| 108 | static void sched_unsleep(struct lwp *, bool); |
| 109 | static void sched_changepri(struct lwp *, pri_t); |
| 110 | static void sched_lendpri(struct lwp *, pri_t); |
| 111 | static void resched_cpu(struct lwp *); |
| 112 | |
| 113 | syncobj_t sleep_syncobj = { |
| 114 | SOBJ_SLEEPQ_SORTED, |
| 115 | sleepq_unsleep, |
| 116 | sleepq_changepri, |
| 117 | sleepq_lendpri, |
| 118 | syncobj_noowner, |
| 119 | }; |
| 120 | |
| 121 | syncobj_t sched_syncobj = { |
| 122 | SOBJ_SLEEPQ_SORTED, |
| 123 | sched_unsleep, |
| 124 | sched_changepri, |
| 125 | sched_lendpri, |
| 126 | syncobj_noowner, |
| 127 | }; |
| 128 | |
| 129 | /* "Lightning bolt": once a second sleep address. */ |
| 130 | kcondvar_t lbolt __cacheline_aligned; |
| 131 | |
| 132 | u_int sched_pstats_ticks __cacheline_aligned; |
| 133 | |
| 134 | /* Preemption event counters. */ |
| 135 | static struct evcnt kpreempt_ev_crit __cacheline_aligned; |
| 136 | static struct evcnt kpreempt_ev_klock __cacheline_aligned; |
| 137 | static struct evcnt kpreempt_ev_immed __cacheline_aligned; |
| 138 | |
| 139 | void |
| 140 | synch_init(void) |
| 141 | { |
| 142 | |
| 143 | cv_init(&lbolt, "lbolt" ); |
| 144 | |
| 145 | evcnt_attach_dynamic(&kpreempt_ev_crit, EVCNT_TYPE_MISC, NULL, |
| 146 | "kpreempt" , "defer: critical section" ); |
| 147 | evcnt_attach_dynamic(&kpreempt_ev_klock, EVCNT_TYPE_MISC, NULL, |
| 148 | "kpreempt" , "defer: kernel_lock" ); |
| 149 | evcnt_attach_dynamic(&kpreempt_ev_immed, EVCNT_TYPE_MISC, NULL, |
| 150 | "kpreempt" , "immediate" ); |
| 151 | } |
| 152 | |
| 153 | /* |
| 154 | * OBSOLETE INTERFACE |
| 155 | * |
| 156 | * General sleep call. Suspends the current LWP until a wakeup is |
| 157 | * performed on the specified identifier. The LWP will then be made |
| 158 | * runnable with the specified priority. Sleeps at most timo/hz seconds (0 |
| 159 | * means no timeout). If pri includes PCATCH flag, signals are checked |
| 160 | * before and after sleeping, else signals are not checked. Returns 0 if |
| 161 | * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a |
| 162 | * signal needs to be delivered, ERESTART is returned if the current system |
| 163 | * call should be restarted if possible, and EINTR is returned if the system |
| 164 | * call should be interrupted by the signal (return EINTR). |
| 165 | */ |
| 166 | int |
| 167 | tsleep(wchan_t ident, pri_t priority, const char *wmesg, int timo) |
| 168 | { |
| 169 | struct lwp *l = curlwp; |
| 170 | sleepq_t *sq; |
| 171 | kmutex_t *mp; |
| 172 | |
| 173 | KASSERT((l->l_pflag & LP_INTR) == 0); |
| 174 | KASSERT(ident != &lbolt); |
| 175 | |
| 176 | if (sleepq_dontsleep(l)) { |
| 177 | (void)sleepq_abort(NULL, 0); |
| 178 | return 0; |
| 179 | } |
| 180 | |
| 181 | l->l_kpriority = true; |
| 182 | sq = sleeptab_lookup(&sleeptab, ident, &mp); |
| 183 | sleepq_enter(sq, l, mp); |
| 184 | sleepq_enqueue(sq, ident, wmesg, &sleep_syncobj); |
| 185 | return sleepq_block(timo, priority & PCATCH); |
| 186 | } |
| 187 | |
| 188 | int |
| 189 | mtsleep(wchan_t ident, pri_t priority, const char *wmesg, int timo, |
| 190 | kmutex_t *mtx) |
| 191 | { |
| 192 | struct lwp *l = curlwp; |
| 193 | sleepq_t *sq; |
| 194 | kmutex_t *mp; |
| 195 | int error; |
| 196 | |
| 197 | KASSERT((l->l_pflag & LP_INTR) == 0); |
| 198 | KASSERT(ident != &lbolt); |
| 199 | |
| 200 | if (sleepq_dontsleep(l)) { |
| 201 | (void)sleepq_abort(mtx, (priority & PNORELOCK) != 0); |
| 202 | return 0; |
| 203 | } |
| 204 | |
| 205 | l->l_kpriority = true; |
| 206 | sq = sleeptab_lookup(&sleeptab, ident, &mp); |
| 207 | sleepq_enter(sq, l, mp); |
| 208 | sleepq_enqueue(sq, ident, wmesg, &sleep_syncobj); |
| 209 | mutex_exit(mtx); |
| 210 | error = sleepq_block(timo, priority & PCATCH); |
| 211 | |
| 212 | if ((priority & PNORELOCK) == 0) |
| 213 | mutex_enter(mtx); |
| 214 | |
| 215 | return error; |
| 216 | } |
| 217 | |
| 218 | /* |
| 219 | * General sleep call for situations where a wake-up is not expected. |
| 220 | */ |
| 221 | int |
| 222 | kpause(const char *wmesg, bool intr, int timo, kmutex_t *mtx) |
| 223 | { |
| 224 | struct lwp *l = curlwp; |
| 225 | kmutex_t *mp; |
| 226 | sleepq_t *sq; |
| 227 | int error; |
| 228 | |
| 229 | KASSERT(!(timo == 0 && intr == false)); |
| 230 | |
| 231 | if (sleepq_dontsleep(l)) |
| 232 | return sleepq_abort(NULL, 0); |
| 233 | |
| 234 | if (mtx != NULL) |
| 235 | mutex_exit(mtx); |
| 236 | l->l_kpriority = true; |
| 237 | sq = sleeptab_lookup(&sleeptab, l, &mp); |
| 238 | sleepq_enter(sq, l, mp); |
| 239 | sleepq_enqueue(sq, l, wmesg, &sleep_syncobj); |
| 240 | error = sleepq_block(timo, intr); |
| 241 | if (mtx != NULL) |
| 242 | mutex_enter(mtx); |
| 243 | |
| 244 | return error; |
| 245 | } |
| 246 | |
| 247 | /* |
| 248 | * OBSOLETE INTERFACE |
| 249 | * |
| 250 | * Make all LWPs sleeping on the specified identifier runnable. |
| 251 | */ |
| 252 | void |
| 253 | wakeup(wchan_t ident) |
| 254 | { |
| 255 | sleepq_t *sq; |
| 256 | kmutex_t *mp; |
| 257 | |
| 258 | if (__predict_false(cold)) |
| 259 | return; |
| 260 | |
| 261 | sq = sleeptab_lookup(&sleeptab, ident, &mp); |
| 262 | sleepq_wake(sq, ident, (u_int)-1, mp); |
| 263 | } |
| 264 | |
| 265 | /* |
| 266 | * General yield call. Puts the current LWP back on its run queue and |
| 267 | * performs a voluntary context switch. Should only be called when the |
| 268 | * current LWP explicitly requests it (eg sched_yield(2)). |
| 269 | */ |
| 270 | void |
| 271 | yield(void) |
| 272 | { |
| 273 | struct lwp *l = curlwp; |
| 274 | |
| 275 | KERNEL_UNLOCK_ALL(l, &l->l_biglocks); |
| 276 | lwp_lock(l); |
| 277 | KASSERT(lwp_locked(l, l->l_cpu->ci_schedstate.spc_lwplock)); |
| 278 | KASSERT(l->l_stat == LSONPROC); |
| 279 | l->l_kpriority = false; |
| 280 | (void)mi_switch(l); |
| 281 | KERNEL_LOCK(l->l_biglocks, l); |
| 282 | } |
| 283 | |
| 284 | /* |
| 285 | * General preemption call. Puts the current LWP back on its run queue |
| 286 | * and performs an involuntary context switch. |
| 287 | */ |
| 288 | void |
| 289 | preempt(void) |
| 290 | { |
| 291 | struct lwp *l = curlwp; |
| 292 | |
| 293 | KERNEL_UNLOCK_ALL(l, &l->l_biglocks); |
| 294 | lwp_lock(l); |
| 295 | KASSERT(lwp_locked(l, l->l_cpu->ci_schedstate.spc_lwplock)); |
| 296 | KASSERT(l->l_stat == LSONPROC); |
| 297 | l->l_kpriority = false; |
| 298 | l->l_nivcsw++; |
| 299 | (void)mi_switch(l); |
| 300 | KERNEL_LOCK(l->l_biglocks, l); |
| 301 | } |
| 302 | |
| 303 | /* |
| 304 | * Handle a request made by another agent to preempt the current LWP |
| 305 | * in-kernel. Usually called when l_dopreempt may be non-zero. |
| 306 | * |
| 307 | * Character addresses for lockstat only. |
| 308 | */ |
| 309 | static char in_critical_section; |
| 310 | static char kernel_lock_held; |
| 311 | static char is_softint; |
| 312 | static char cpu_kpreempt_enter_fail; |
| 313 | |
| 314 | bool |
| 315 | kpreempt(uintptr_t where) |
| 316 | { |
| 317 | uintptr_t failed; |
| 318 | lwp_t *l; |
| 319 | int s, dop, lsflag; |
| 320 | |
| 321 | l = curlwp; |
| 322 | failed = 0; |
| 323 | while ((dop = l->l_dopreempt) != 0) { |
| 324 | if (l->l_stat != LSONPROC) { |
| 325 | /* |
| 326 | * About to block (or die), let it happen. |
| 327 | * Doesn't really count as "preemption has |
| 328 | * been blocked", since we're going to |
| 329 | * context switch. |
| 330 | */ |
| 331 | l->l_dopreempt = 0; |
| 332 | return true; |
| 333 | } |
| 334 | if (__predict_false((l->l_flag & LW_IDLE) != 0)) { |
| 335 | /* Can't preempt idle loop, don't count as failure. */ |
| 336 | l->l_dopreempt = 0; |
| 337 | return true; |
| 338 | } |
| 339 | if (__predict_false(l->l_nopreempt != 0)) { |
| 340 | /* LWP holds preemption disabled, explicitly. */ |
| 341 | if ((dop & DOPREEMPT_COUNTED) == 0) { |
| 342 | kpreempt_ev_crit.ev_count++; |
| 343 | } |
| 344 | failed = (uintptr_t)&in_critical_section; |
| 345 | break; |
| 346 | } |
| 347 | if (__predict_false((l->l_pflag & LP_INTR) != 0)) { |
| 348 | /* Can't preempt soft interrupts yet. */ |
| 349 | l->l_dopreempt = 0; |
| 350 | failed = (uintptr_t)&is_softint; |
| 351 | break; |
| 352 | } |
| 353 | s = splsched(); |
| 354 | if (__predict_false(l->l_blcnt != 0 || |
| 355 | curcpu()->ci_biglock_wanted != NULL)) { |
| 356 | /* Hold or want kernel_lock, code is not MT safe. */ |
| 357 | splx(s); |
| 358 | if ((dop & DOPREEMPT_COUNTED) == 0) { |
| 359 | kpreempt_ev_klock.ev_count++; |
| 360 | } |
| 361 | failed = (uintptr_t)&kernel_lock_held; |
| 362 | break; |
| 363 | } |
| 364 | if (__predict_false(!cpu_kpreempt_enter(where, s))) { |
| 365 | /* |
| 366 | * It may be that the IPL is too high. |
| 367 | * kpreempt_enter() can schedule an |
| 368 | * interrupt to retry later. |
| 369 | */ |
| 370 | splx(s); |
| 371 | failed = (uintptr_t)&cpu_kpreempt_enter_fail; |
| 372 | break; |
| 373 | } |
| 374 | /* Do it! */ |
| 375 | if (__predict_true((dop & DOPREEMPT_COUNTED) == 0)) { |
| 376 | kpreempt_ev_immed.ev_count++; |
| 377 | } |
| 378 | lwp_lock(l); |
| 379 | mi_switch(l); |
| 380 | l->l_nopreempt++; |
| 381 | splx(s); |
| 382 | |
| 383 | /* Take care of any MD cleanup. */ |
| 384 | cpu_kpreempt_exit(where); |
| 385 | l->l_nopreempt--; |
| 386 | } |
| 387 | |
| 388 | if (__predict_true(!failed)) { |
| 389 | return false; |
| 390 | } |
| 391 | |
| 392 | /* Record preemption failure for reporting via lockstat. */ |
| 393 | atomic_or_uint(&l->l_dopreempt, DOPREEMPT_COUNTED); |
| 394 | lsflag = 0; |
| 395 | LOCKSTAT_ENTER(lsflag); |
| 396 | if (__predict_false(lsflag)) { |
| 397 | if (where == 0) { |
| 398 | where = (uintptr_t)__builtin_return_address(0); |
| 399 | } |
| 400 | /* Preemption is on, might recurse, so make it atomic. */ |
| 401 | if (atomic_cas_ptr_ni((void *)&l->l_pfailaddr, NULL, |
| 402 | (void *)where) == NULL) { |
| 403 | LOCKSTAT_START_TIMER(lsflag, l->l_pfailtime); |
| 404 | l->l_pfaillock = failed; |
| 405 | } |
| 406 | } |
| 407 | LOCKSTAT_EXIT(lsflag); |
| 408 | return true; |
| 409 | } |
| 410 | |
| 411 | /* |
| 412 | * Return true if preemption is explicitly disabled. |
| 413 | */ |
| 414 | bool |
| 415 | kpreempt_disabled(void) |
| 416 | { |
| 417 | const lwp_t *l = curlwp; |
| 418 | |
| 419 | return l->l_nopreempt != 0 || l->l_stat == LSZOMB || |
| 420 | (l->l_flag & LW_IDLE) != 0 || cpu_kpreempt_disabled(); |
| 421 | } |
| 422 | |
| 423 | /* |
| 424 | * Disable kernel preemption. |
| 425 | */ |
| 426 | void |
| 427 | kpreempt_disable(void) |
| 428 | { |
| 429 | |
| 430 | KPREEMPT_DISABLE(curlwp); |
| 431 | } |
| 432 | |
| 433 | /* |
| 434 | * Reenable kernel preemption. |
| 435 | */ |
| 436 | void |
| 437 | kpreempt_enable(void) |
| 438 | { |
| 439 | |
| 440 | KPREEMPT_ENABLE(curlwp); |
| 441 | } |
| 442 | |
| 443 | /* |
| 444 | * Compute the amount of time during which the current lwp was running. |
| 445 | * |
| 446 | * - update l_rtime unless it's an idle lwp. |
| 447 | */ |
| 448 | |
| 449 | void |
| 450 | updatertime(lwp_t *l, const struct bintime *now) |
| 451 | { |
| 452 | |
| 453 | if (__predict_false(l->l_flag & LW_IDLE)) |
| 454 | return; |
| 455 | |
| 456 | /* rtime += now - stime */ |
| 457 | bintime_add(&l->l_rtime, now); |
| 458 | bintime_sub(&l->l_rtime, &l->l_stime); |
| 459 | } |
| 460 | |
| 461 | /* |
| 462 | * Select next LWP from the current CPU to run.. |
| 463 | */ |
| 464 | static inline lwp_t * |
| 465 | nextlwp(struct cpu_info *ci, struct schedstate_percpu *spc) |
| 466 | { |
| 467 | lwp_t *newl; |
| 468 | |
| 469 | /* |
| 470 | * Let sched_nextlwp() select the LWP to run the CPU next. |
| 471 | * If no LWP is runnable, select the idle LWP. |
| 472 | * |
| 473 | * Note that spc_lwplock might not necessary be held, and |
| 474 | * new thread would be unlocked after setting the LWP-lock. |
| 475 | */ |
| 476 | newl = sched_nextlwp(); |
| 477 | if (newl != NULL) { |
| 478 | sched_dequeue(newl); |
| 479 | KASSERT(lwp_locked(newl, spc->spc_mutex)); |
| 480 | KASSERT(newl->l_cpu == ci); |
| 481 | newl->l_stat = LSONPROC; |
| 482 | newl->l_pflag |= LP_RUNNING; |
| 483 | lwp_setlock(newl, spc->spc_lwplock); |
| 484 | } else { |
| 485 | newl = ci->ci_data.cpu_idlelwp; |
| 486 | newl->l_stat = LSONPROC; |
| 487 | newl->l_pflag |= LP_RUNNING; |
| 488 | } |
| 489 | |
| 490 | /* |
| 491 | * Only clear want_resched if there are no pending (slow) |
| 492 | * software interrupts. |
| 493 | */ |
| 494 | ci->ci_want_resched = ci->ci_data.cpu_softints; |
| 495 | spc->spc_flags &= ~SPCF_SWITCHCLEAR; |
| 496 | spc->spc_curpriority = lwp_eprio(newl); |
| 497 | |
| 498 | return newl; |
| 499 | } |
| 500 | |
| 501 | /* |
| 502 | * The machine independent parts of context switch. |
| 503 | * |
| 504 | * Returns 1 if another LWP was actually run. |
| 505 | */ |
| 506 | int |
| 507 | mi_switch(lwp_t *l) |
| 508 | { |
| 509 | struct cpu_info *ci; |
| 510 | struct schedstate_percpu *spc; |
| 511 | struct lwp *newl; |
| 512 | int retval, oldspl; |
| 513 | struct bintime bt; |
| 514 | bool returning; |
| 515 | |
| 516 | KASSERT(lwp_locked(l, NULL)); |
| 517 | KASSERT(kpreempt_disabled()); |
| 518 | LOCKDEBUG_BARRIER(l->l_mutex, 1); |
| 519 | |
| 520 | kstack_check_magic(l); |
| 521 | |
| 522 | binuptime(&bt); |
| 523 | |
| 524 | KASSERTMSG(l == curlwp, "l %p curlwp %p" , l, curlwp); |
| 525 | KASSERT((l->l_pflag & LP_RUNNING) != 0); |
| 526 | KASSERT(l->l_cpu == curcpu()); |
| 527 | ci = l->l_cpu; |
| 528 | spc = &ci->ci_schedstate; |
| 529 | returning = false; |
| 530 | newl = NULL; |
| 531 | |
| 532 | /* |
| 533 | * If we have been asked to switch to a specific LWP, then there |
| 534 | * is no need to inspect the run queues. If a soft interrupt is |
| 535 | * blocking, then return to the interrupted thread without adjusting |
| 536 | * VM context or its start time: neither have been changed in order |
| 537 | * to take the interrupt. |
| 538 | */ |
| 539 | if (l->l_switchto != NULL) { |
| 540 | if ((l->l_pflag & LP_INTR) != 0) { |
| 541 | returning = true; |
| 542 | softint_block(l); |
| 543 | if ((l->l_pflag & LP_TIMEINTR) != 0) |
| 544 | updatertime(l, &bt); |
| 545 | } |
| 546 | newl = l->l_switchto; |
| 547 | l->l_switchto = NULL; |
| 548 | } |
| 549 | #ifndef __HAVE_FAST_SOFTINTS |
| 550 | else if (ci->ci_data.cpu_softints != 0) { |
| 551 | /* There are pending soft interrupts, so pick one. */ |
| 552 | newl = softint_picklwp(); |
| 553 | newl->l_stat = LSONPROC; |
| 554 | newl->l_pflag |= LP_RUNNING; |
| 555 | } |
| 556 | #endif /* !__HAVE_FAST_SOFTINTS */ |
| 557 | |
| 558 | /* Count time spent in current system call */ |
| 559 | if (!returning) { |
| 560 | SYSCALL_TIME_SLEEP(l); |
| 561 | |
| 562 | /* |
| 563 | * XXXSMP If we are using h/w performance counters, |
| 564 | * save context. |
| 565 | */ |
| 566 | #if PERFCTRS |
| 567 | if (PMC_ENABLED(l->l_proc)) { |
| 568 | pmc_save_context(l->l_proc); |
| 569 | } |
| 570 | #endif |
| 571 | updatertime(l, &bt); |
| 572 | } |
| 573 | |
| 574 | /* Lock the runqueue */ |
| 575 | KASSERT(l->l_stat != LSRUN); |
| 576 | mutex_spin_enter(spc->spc_mutex); |
| 577 | |
| 578 | /* |
| 579 | * If on the CPU and we have gotten this far, then we must yield. |
| 580 | */ |
| 581 | if (l->l_stat == LSONPROC && l != newl) { |
| 582 | KASSERT(lwp_locked(l, spc->spc_lwplock)); |
| 583 | if ((l->l_flag & LW_IDLE) == 0) { |
| 584 | l->l_stat = LSRUN; |
| 585 | lwp_setlock(l, spc->spc_mutex); |
| 586 | sched_enqueue(l, true); |
| 587 | /* |
| 588 | * Handle migration. Note that "migrating LWP" may |
| 589 | * be reset here, if interrupt/preemption happens |
| 590 | * early in idle LWP. |
| 591 | */ |
| 592 | if (l->l_target_cpu != NULL) { |
| 593 | KASSERT((l->l_pflag & LP_INTR) == 0); |
| 594 | spc->spc_migrating = l; |
| 595 | } |
| 596 | } else |
| 597 | l->l_stat = LSIDL; |
| 598 | } |
| 599 | |
| 600 | /* Pick new LWP to run. */ |
| 601 | if (newl == NULL) { |
| 602 | newl = nextlwp(ci, spc); |
| 603 | } |
| 604 | |
| 605 | /* Items that must be updated with the CPU locked. */ |
| 606 | if (!returning) { |
| 607 | /* Update the new LWP's start time. */ |
| 608 | newl->l_stime = bt; |
| 609 | |
| 610 | /* |
| 611 | * ci_curlwp changes when a fast soft interrupt occurs. |
| 612 | * We use cpu_onproc to keep track of which kernel or |
| 613 | * user thread is running 'underneath' the software |
| 614 | * interrupt. This is important for time accounting, |
| 615 | * itimers and forcing user threads to preempt (aston). |
| 616 | */ |
| 617 | ci->ci_data.cpu_onproc = newl; |
| 618 | } |
| 619 | |
| 620 | /* |
| 621 | * Preemption related tasks. Must be done with the current |
| 622 | * CPU locked. |
| 623 | */ |
| 624 | cpu_did_resched(l); |
| 625 | l->l_dopreempt = 0; |
| 626 | if (__predict_false(l->l_pfailaddr != 0)) { |
| 627 | LOCKSTAT_FLAG(lsflag); |
| 628 | LOCKSTAT_ENTER(lsflag); |
| 629 | LOCKSTAT_STOP_TIMER(lsflag, l->l_pfailtime); |
| 630 | LOCKSTAT_EVENT_RA(lsflag, l->l_pfaillock, LB_NOPREEMPT|LB_SPIN, |
| 631 | 1, l->l_pfailtime, l->l_pfailaddr); |
| 632 | LOCKSTAT_EXIT(lsflag); |
| 633 | l->l_pfailtime = 0; |
| 634 | l->l_pfaillock = 0; |
| 635 | l->l_pfailaddr = 0; |
| 636 | } |
| 637 | |
| 638 | if (l != newl) { |
| 639 | struct lwp *prevlwp; |
| 640 | |
| 641 | /* Release all locks, but leave the current LWP locked */ |
| 642 | if (l->l_mutex == spc->spc_mutex) { |
| 643 | /* |
| 644 | * Drop spc_lwplock, if the current LWP has been moved |
| 645 | * to the run queue (it is now locked by spc_mutex). |
| 646 | */ |
| 647 | mutex_spin_exit(spc->spc_lwplock); |
| 648 | } else { |
| 649 | /* |
| 650 | * Otherwise, drop the spc_mutex, we are done with the |
| 651 | * run queues. |
| 652 | */ |
| 653 | mutex_spin_exit(spc->spc_mutex); |
| 654 | } |
| 655 | |
| 656 | /* |
| 657 | * Mark that context switch is going to be performed |
| 658 | * for this LWP, to protect it from being switched |
| 659 | * to on another CPU. |
| 660 | */ |
| 661 | KASSERT(l->l_ctxswtch == 0); |
| 662 | l->l_ctxswtch = 1; |
| 663 | l->l_ncsw++; |
| 664 | KASSERT((l->l_pflag & LP_RUNNING) != 0); |
| 665 | l->l_pflag &= ~LP_RUNNING; |
| 666 | |
| 667 | /* |
| 668 | * Increase the count of spin-mutexes before the release |
| 669 | * of the last lock - we must remain at IPL_SCHED during |
| 670 | * the context switch. |
| 671 | */ |
| 672 | KASSERTMSG(ci->ci_mtx_count == -1, |
| 673 | "%s: cpu%u: ci_mtx_count (%d) != -1 " |
| 674 | "(block with spin-mutex held)" , |
| 675 | __func__, cpu_index(ci), ci->ci_mtx_count); |
| 676 | oldspl = MUTEX_SPIN_OLDSPL(ci); |
| 677 | ci->ci_mtx_count--; |
| 678 | lwp_unlock(l); |
| 679 | |
| 680 | /* Count the context switch on this CPU. */ |
| 681 | ci->ci_data.cpu_nswtch++; |
| 682 | |
| 683 | /* Update status for lwpctl, if present. */ |
| 684 | if (l->l_lwpctl != NULL) |
| 685 | l->l_lwpctl->lc_curcpu = LWPCTL_CPU_NONE; |
| 686 | |
| 687 | /* |
| 688 | * Save old VM context, unless a soft interrupt |
| 689 | * handler is blocking. |
| 690 | */ |
| 691 | if (!returning) |
| 692 | pmap_deactivate(l); |
| 693 | |
| 694 | /* |
| 695 | * We may need to spin-wait if 'newl' is still |
| 696 | * context switching on another CPU. |
| 697 | */ |
| 698 | if (__predict_false(newl->l_ctxswtch != 0)) { |
| 699 | u_int count; |
| 700 | count = SPINLOCK_BACKOFF_MIN; |
| 701 | while (newl->l_ctxswtch) |
| 702 | SPINLOCK_BACKOFF(count); |
| 703 | } |
| 704 | |
| 705 | /* |
| 706 | * If DTrace has set the active vtime enum to anything |
| 707 | * other than INACTIVE (0), then it should have set the |
| 708 | * function to call. |
| 709 | */ |
| 710 | if (__predict_false(dtrace_vtime_active)) { |
| 711 | (*dtrace_vtime_switch_func)(newl); |
| 712 | } |
| 713 | |
| 714 | /* Switch to the new LWP.. */ |
| 715 | #ifdef MULTIPROCESSOR |
| 716 | KASSERT(curlwp == ci->ci_curlwp); |
| 717 | #endif |
| 718 | KASSERTMSG(l == curlwp, "l %p curlwp %p" , l, curlwp); |
| 719 | prevlwp = cpu_switchto(l, newl, returning); |
| 720 | ci = curcpu(); |
| 721 | #ifdef MULTIPROCESSOR |
| 722 | KASSERT(curlwp == ci->ci_curlwp); |
| 723 | #endif |
| 724 | KASSERTMSG(l == curlwp, "l %p curlwp %p prevlwp %p" , |
| 725 | l, curlwp, prevlwp); |
| 726 | |
| 727 | /* |
| 728 | * Switched away - we have new curlwp. |
| 729 | * Restore VM context and IPL. |
| 730 | */ |
| 731 | pmap_activate(l); |
| 732 | uvm_emap_switch(l); |
| 733 | pcu_switchpoint(l); |
| 734 | |
| 735 | if (prevlwp != NULL) { |
| 736 | /* Normalize the count of the spin-mutexes */ |
| 737 | ci->ci_mtx_count++; |
| 738 | /* Unmark the state of context switch */ |
| 739 | membar_exit(); |
| 740 | prevlwp->l_ctxswtch = 0; |
| 741 | } |
| 742 | |
| 743 | /* Update status for lwpctl, if present. */ |
| 744 | if (l->l_lwpctl != NULL) { |
| 745 | l->l_lwpctl->lc_curcpu = (int)cpu_index(ci); |
| 746 | l->l_lwpctl->lc_pctr++; |
| 747 | } |
| 748 | |
| 749 | /* Note trip through cpu_switchto(). */ |
| 750 | pserialize_switchpoint(); |
| 751 | |
| 752 | KASSERT(l->l_cpu == ci); |
| 753 | splx(oldspl); |
| 754 | /* |
| 755 | * note that, unless the caller disabled preemption, |
| 756 | * we can be preempted at any time after the above splx() call. |
| 757 | */ |
| 758 | retval = 1; |
| 759 | } else { |
| 760 | /* Nothing to do - just unlock and return. */ |
| 761 | mutex_spin_exit(spc->spc_mutex); |
| 762 | lwp_unlock(l); |
| 763 | retval = 0; |
| 764 | } |
| 765 | |
| 766 | KASSERT(l == curlwp); |
| 767 | KASSERT(l->l_stat == LSONPROC); |
| 768 | |
| 769 | /* |
| 770 | * XXXSMP If we are using h/w performance counters, restore context. |
| 771 | * XXXSMP preemption problem. |
| 772 | */ |
| 773 | #if PERFCTRS |
| 774 | if (PMC_ENABLED(l->l_proc)) { |
| 775 | pmc_restore_context(l->l_proc); |
| 776 | } |
| 777 | #endif |
| 778 | SYSCALL_TIME_WAKEUP(l); |
| 779 | LOCKDEBUG_BARRIER(NULL, 1); |
| 780 | |
| 781 | return retval; |
| 782 | } |
| 783 | |
| 784 | /* |
| 785 | * The machine independent parts of context switch to oblivion. |
| 786 | * Does not return. Call with the LWP unlocked. |
| 787 | */ |
| 788 | void |
| 789 | lwp_exit_switchaway(lwp_t *l) |
| 790 | { |
| 791 | struct cpu_info *ci; |
| 792 | struct lwp *newl; |
| 793 | struct bintime bt; |
| 794 | |
| 795 | ci = l->l_cpu; |
| 796 | |
| 797 | KASSERT(kpreempt_disabled()); |
| 798 | KASSERT(l->l_stat == LSZOMB || l->l_stat == LSIDL); |
| 799 | KASSERT(ci == curcpu()); |
| 800 | LOCKDEBUG_BARRIER(NULL, 0); |
| 801 | |
| 802 | kstack_check_magic(l); |
| 803 | |
| 804 | /* Count time spent in current system call */ |
| 805 | SYSCALL_TIME_SLEEP(l); |
| 806 | binuptime(&bt); |
| 807 | updatertime(l, &bt); |
| 808 | |
| 809 | /* Must stay at IPL_SCHED even after releasing run queue lock. */ |
| 810 | (void)splsched(); |
| 811 | |
| 812 | /* |
| 813 | * Let sched_nextlwp() select the LWP to run the CPU next. |
| 814 | * If no LWP is runnable, select the idle LWP. |
| 815 | * |
| 816 | * Note that spc_lwplock might not necessary be held, and |
| 817 | * new thread would be unlocked after setting the LWP-lock. |
| 818 | */ |
| 819 | spc_lock(ci); |
| 820 | #ifndef __HAVE_FAST_SOFTINTS |
| 821 | if (ci->ci_data.cpu_softints != 0) { |
| 822 | /* There are pending soft interrupts, so pick one. */ |
| 823 | newl = softint_picklwp(); |
| 824 | newl->l_stat = LSONPROC; |
| 825 | newl->l_pflag |= LP_RUNNING; |
| 826 | } else |
| 827 | #endif /* !__HAVE_FAST_SOFTINTS */ |
| 828 | { |
| 829 | newl = nextlwp(ci, &ci->ci_schedstate); |
| 830 | } |
| 831 | |
| 832 | /* Update the new LWP's start time. */ |
| 833 | newl->l_stime = bt; |
| 834 | l->l_pflag &= ~LP_RUNNING; |
| 835 | |
| 836 | /* |
| 837 | * ci_curlwp changes when a fast soft interrupt occurs. |
| 838 | * We use cpu_onproc to keep track of which kernel or |
| 839 | * user thread is running 'underneath' the software |
| 840 | * interrupt. This is important for time accounting, |
| 841 | * itimers and forcing user threads to preempt (aston). |
| 842 | */ |
| 843 | ci->ci_data.cpu_onproc = newl; |
| 844 | |
| 845 | /* |
| 846 | * Preemption related tasks. Must be done with the current |
| 847 | * CPU locked. |
| 848 | */ |
| 849 | cpu_did_resched(l); |
| 850 | |
| 851 | /* Unlock the run queue. */ |
| 852 | spc_unlock(ci); |
| 853 | |
| 854 | /* Count the context switch on this CPU. */ |
| 855 | ci->ci_data.cpu_nswtch++; |
| 856 | |
| 857 | /* Update status for lwpctl, if present. */ |
| 858 | if (l->l_lwpctl != NULL) |
| 859 | l->l_lwpctl->lc_curcpu = LWPCTL_CPU_EXITED; |
| 860 | |
| 861 | /* |
| 862 | * We may need to spin-wait if 'newl' is still |
| 863 | * context switching on another CPU. |
| 864 | */ |
| 865 | if (__predict_false(newl->l_ctxswtch != 0)) { |
| 866 | u_int count; |
| 867 | count = SPINLOCK_BACKOFF_MIN; |
| 868 | while (newl->l_ctxswtch) |
| 869 | SPINLOCK_BACKOFF(count); |
| 870 | } |
| 871 | |
| 872 | /* |
| 873 | * If DTrace has set the active vtime enum to anything |
| 874 | * other than INACTIVE (0), then it should have set the |
| 875 | * function to call. |
| 876 | */ |
| 877 | if (__predict_false(dtrace_vtime_active)) { |
| 878 | (*dtrace_vtime_switch_func)(newl); |
| 879 | } |
| 880 | |
| 881 | /* Switch to the new LWP.. */ |
| 882 | (void)cpu_switchto(NULL, newl, false); |
| 883 | |
| 884 | for (;;) continue; /* XXX: convince gcc about "noreturn" */ |
| 885 | /* NOTREACHED */ |
| 886 | } |
| 887 | |
| 888 | /* |
| 889 | * setrunnable: change LWP state to be runnable, placing it on the run queue. |
| 890 | * |
| 891 | * Call with the process and LWP locked. Will return with the LWP unlocked. |
| 892 | */ |
| 893 | void |
| 894 | setrunnable(struct lwp *l) |
| 895 | { |
| 896 | struct proc *p = l->l_proc; |
| 897 | struct cpu_info *ci; |
| 898 | |
| 899 | KASSERT((l->l_flag & LW_IDLE) == 0); |
| 900 | KASSERT(mutex_owned(p->p_lock)); |
| 901 | KASSERT(lwp_locked(l, NULL)); |
| 902 | KASSERT(l->l_mutex != l->l_cpu->ci_schedstate.spc_mutex); |
| 903 | |
| 904 | switch (l->l_stat) { |
| 905 | case LSSTOP: |
| 906 | /* |
| 907 | * If we're being traced (possibly because someone attached us |
| 908 | * while we were stopped), check for a signal from the debugger. |
| 909 | */ |
| 910 | if ((p->p_slflag & PSL_TRACED) != 0 && p->p_xsig != 0) |
| 911 | signotify(l); |
| 912 | p->p_nrlwps++; |
| 913 | break; |
| 914 | case LSSUSPENDED: |
| 915 | l->l_flag &= ~LW_WSUSPEND; |
| 916 | p->p_nrlwps++; |
| 917 | cv_broadcast(&p->p_lwpcv); |
| 918 | break; |
| 919 | case LSSLEEP: |
| 920 | KASSERT(l->l_wchan != NULL); |
| 921 | break; |
| 922 | default: |
| 923 | panic("setrunnable: lwp %p state was %d" , l, l->l_stat); |
| 924 | } |
| 925 | |
| 926 | /* |
| 927 | * If the LWP was sleeping, start it again. |
| 928 | */ |
| 929 | if (l->l_wchan != NULL) { |
| 930 | l->l_stat = LSSLEEP; |
| 931 | /* lwp_unsleep() will release the lock. */ |
| 932 | lwp_unsleep(l, true); |
| 933 | return; |
| 934 | } |
| 935 | |
| 936 | /* |
| 937 | * If the LWP is still on the CPU, mark it as LSONPROC. It may be |
| 938 | * about to call mi_switch(), in which case it will yield. |
| 939 | */ |
| 940 | if ((l->l_pflag & LP_RUNNING) != 0) { |
| 941 | l->l_stat = LSONPROC; |
| 942 | l->l_slptime = 0; |
| 943 | lwp_unlock(l); |
| 944 | return; |
| 945 | } |
| 946 | |
| 947 | /* |
| 948 | * Look for a CPU to run. |
| 949 | * Set the LWP runnable. |
| 950 | */ |
| 951 | ci = sched_takecpu(l); |
| 952 | l->l_cpu = ci; |
| 953 | spc_lock(ci); |
| 954 | lwp_unlock_to(l, ci->ci_schedstate.spc_mutex); |
| 955 | sched_setrunnable(l); |
| 956 | l->l_stat = LSRUN; |
| 957 | l->l_slptime = 0; |
| 958 | |
| 959 | sched_enqueue(l, false); |
| 960 | resched_cpu(l); |
| 961 | lwp_unlock(l); |
| 962 | } |
| 963 | |
| 964 | /* |
| 965 | * suspendsched: |
| 966 | * |
| 967 | * Convert all non-LW_SYSTEM LSSLEEP or LSRUN LWPs to LSSUSPENDED. |
| 968 | */ |
| 969 | void |
| 970 | suspendsched(void) |
| 971 | { |
| 972 | CPU_INFO_ITERATOR cii; |
| 973 | struct cpu_info *ci; |
| 974 | struct lwp *l; |
| 975 | struct proc *p; |
| 976 | |
| 977 | /* |
| 978 | * We do this by process in order not to violate the locking rules. |
| 979 | */ |
| 980 | mutex_enter(proc_lock); |
| 981 | PROCLIST_FOREACH(p, &allproc) { |
| 982 | mutex_enter(p->p_lock); |
| 983 | if ((p->p_flag & PK_SYSTEM) != 0) { |
| 984 | mutex_exit(p->p_lock); |
| 985 | continue; |
| 986 | } |
| 987 | |
| 988 | if (p->p_stat != SSTOP) { |
| 989 | if (p->p_stat != SZOMB && p->p_stat != SDEAD) { |
| 990 | p->p_pptr->p_nstopchild++; |
| 991 | p->p_waited = 0; |
| 992 | } |
| 993 | p->p_stat = SSTOP; |
| 994 | } |
| 995 | |
| 996 | LIST_FOREACH(l, &p->p_lwps, l_sibling) { |
| 997 | if (l == curlwp) |
| 998 | continue; |
| 999 | |
| 1000 | lwp_lock(l); |
| 1001 | |
| 1002 | /* |
| 1003 | * Set L_WREBOOT so that the LWP will suspend itself |
| 1004 | * when it tries to return to user mode. We want to |
| 1005 | * try and get to get as many LWPs as possible to |
| 1006 | * the user / kernel boundary, so that they will |
| 1007 | * release any locks that they hold. |
| 1008 | */ |
| 1009 | l->l_flag |= (LW_WREBOOT | LW_WSUSPEND); |
| 1010 | |
| 1011 | if (l->l_stat == LSSLEEP && |
| 1012 | (l->l_flag & LW_SINTR) != 0) { |
| 1013 | /* setrunnable() will release the lock. */ |
| 1014 | setrunnable(l); |
| 1015 | continue; |
| 1016 | } |
| 1017 | |
| 1018 | lwp_unlock(l); |
| 1019 | } |
| 1020 | |
| 1021 | mutex_exit(p->p_lock); |
| 1022 | } |
| 1023 | mutex_exit(proc_lock); |
| 1024 | |
| 1025 | /* |
| 1026 | * Kick all CPUs to make them preempt any LWPs running in user mode. |
| 1027 | * They'll trap into the kernel and suspend themselves in userret(). |
| 1028 | */ |
| 1029 | for (CPU_INFO_FOREACH(cii, ci)) { |
| 1030 | spc_lock(ci); |
| 1031 | cpu_need_resched(ci, RESCHED_IMMED); |
| 1032 | spc_unlock(ci); |
| 1033 | } |
| 1034 | } |
| 1035 | |
| 1036 | /* |
| 1037 | * sched_unsleep: |
| 1038 | * |
| 1039 | * The is called when the LWP has not been awoken normally but instead |
| 1040 | * interrupted: for example, if the sleep timed out. Because of this, |
| 1041 | * it's not a valid action for running or idle LWPs. |
| 1042 | */ |
| 1043 | static void |
| 1044 | sched_unsleep(struct lwp *l, bool cleanup) |
| 1045 | { |
| 1046 | |
| 1047 | lwp_unlock(l); |
| 1048 | panic("sched_unsleep" ); |
| 1049 | } |
| 1050 | |
| 1051 | static void |
| 1052 | resched_cpu(struct lwp *l) |
| 1053 | { |
| 1054 | struct cpu_info *ci = l->l_cpu; |
| 1055 | |
| 1056 | KASSERT(lwp_locked(l, NULL)); |
| 1057 | if (lwp_eprio(l) > ci->ci_schedstate.spc_curpriority) |
| 1058 | cpu_need_resched(ci, 0); |
| 1059 | } |
| 1060 | |
| 1061 | static void |
| 1062 | sched_changepri(struct lwp *l, pri_t pri) |
| 1063 | { |
| 1064 | |
| 1065 | KASSERT(lwp_locked(l, NULL)); |
| 1066 | |
| 1067 | if (l->l_stat == LSRUN) { |
| 1068 | KASSERT(lwp_locked(l, l->l_cpu->ci_schedstate.spc_mutex)); |
| 1069 | sched_dequeue(l); |
| 1070 | l->l_priority = pri; |
| 1071 | sched_enqueue(l, false); |
| 1072 | } else { |
| 1073 | l->l_priority = pri; |
| 1074 | } |
| 1075 | resched_cpu(l); |
| 1076 | } |
| 1077 | |
| 1078 | static void |
| 1079 | sched_lendpri(struct lwp *l, pri_t pri) |
| 1080 | { |
| 1081 | |
| 1082 | KASSERT(lwp_locked(l, NULL)); |
| 1083 | |
| 1084 | if (l->l_stat == LSRUN) { |
| 1085 | KASSERT(lwp_locked(l, l->l_cpu->ci_schedstate.spc_mutex)); |
| 1086 | sched_dequeue(l); |
| 1087 | l->l_inheritedprio = pri; |
| 1088 | l->l_auxprio = MAX(l->l_inheritedprio, l->l_protectprio); |
| 1089 | sched_enqueue(l, false); |
| 1090 | } else { |
| 1091 | l->l_inheritedprio = pri; |
| 1092 | l->l_auxprio = MAX(l->l_inheritedprio, l->l_protectprio); |
| 1093 | } |
| 1094 | resched_cpu(l); |
| 1095 | } |
| 1096 | |
| 1097 | struct lwp * |
| 1098 | syncobj_noowner(wchan_t wchan) |
| 1099 | { |
| 1100 | |
| 1101 | return NULL; |
| 1102 | } |
| 1103 | |
| 1104 | /* Decay 95% of proc::p_pctcpu in 60 seconds, ccpu = exp(-1/20) */ |
| 1105 | const fixpt_t ccpu = 0.95122942450071400909 * FSCALE; |
| 1106 | |
| 1107 | /* |
| 1108 | * Constants for averages over 1, 5 and 15 minutes when sampling at |
| 1109 | * 5 second intervals. |
| 1110 | */ |
| 1111 | static const fixpt_t cexp[ ] = { |
| 1112 | 0.9200444146293232 * FSCALE, /* exp(-1/12) */ |
| 1113 | 0.9834714538216174 * FSCALE, /* exp(-1/60) */ |
| 1114 | 0.9944598480048967 * FSCALE, /* exp(-1/180) */ |
| 1115 | }; |
| 1116 | |
| 1117 | /* |
| 1118 | * sched_pstats: |
| 1119 | * |
| 1120 | * => Update process statistics and check CPU resource allocation. |
| 1121 | * => Call scheduler-specific hook to eventually adjust LWP priorities. |
| 1122 | * => Compute load average of a quantity on 1, 5 and 15 minute intervals. |
| 1123 | */ |
| 1124 | void |
| 1125 | sched_pstats(void) |
| 1126 | { |
| 1127 | extern struct loadavg averunnable; |
| 1128 | struct loadavg *avg = &averunnable; |
| 1129 | const int clkhz = (stathz != 0 ? stathz : hz); |
| 1130 | static bool backwards = false; |
| 1131 | static u_int lavg_count = 0; |
| 1132 | struct proc *p; |
| 1133 | int nrun; |
| 1134 | |
| 1135 | sched_pstats_ticks++; |
| 1136 | if (++lavg_count >= 5) { |
| 1137 | lavg_count = 0; |
| 1138 | nrun = 0; |
| 1139 | } |
| 1140 | mutex_enter(proc_lock); |
| 1141 | PROCLIST_FOREACH(p, &allproc) { |
| 1142 | struct lwp *l; |
| 1143 | struct rlimit *rlim; |
| 1144 | time_t runtm; |
| 1145 | int sig; |
| 1146 | |
| 1147 | /* Increment sleep time (if sleeping), ignore overflow. */ |
| 1148 | mutex_enter(p->p_lock); |
| 1149 | runtm = p->p_rtime.sec; |
| 1150 | LIST_FOREACH(l, &p->p_lwps, l_sibling) { |
| 1151 | fixpt_t lpctcpu; |
| 1152 | u_int lcpticks; |
| 1153 | |
| 1154 | if (__predict_false((l->l_flag & LW_IDLE) != 0)) |
| 1155 | continue; |
| 1156 | lwp_lock(l); |
| 1157 | runtm += l->l_rtime.sec; |
| 1158 | l->l_swtime++; |
| 1159 | sched_lwp_stats(l); |
| 1160 | |
| 1161 | /* For load average calculation. */ |
| 1162 | if (__predict_false(lavg_count == 0) && |
| 1163 | (l->l_flag & (LW_SINTR | LW_SYSTEM)) == 0) { |
| 1164 | switch (l->l_stat) { |
| 1165 | case LSSLEEP: |
| 1166 | if (l->l_slptime > 1) { |
| 1167 | break; |
| 1168 | } |
| 1169 | case LSRUN: |
| 1170 | case LSONPROC: |
| 1171 | case LSIDL: |
| 1172 | nrun++; |
| 1173 | } |
| 1174 | } |
| 1175 | lwp_unlock(l); |
| 1176 | |
| 1177 | l->l_pctcpu = (l->l_pctcpu * ccpu) >> FSHIFT; |
| 1178 | if (l->l_slptime != 0) |
| 1179 | continue; |
| 1180 | |
| 1181 | lpctcpu = l->l_pctcpu; |
| 1182 | lcpticks = atomic_swap_uint(&l->l_cpticks, 0); |
| 1183 | lpctcpu += ((FSCALE - ccpu) * |
| 1184 | (lcpticks * FSCALE / clkhz)) >> FSHIFT; |
| 1185 | l->l_pctcpu = lpctcpu; |
| 1186 | } |
| 1187 | /* Calculating p_pctcpu only for ps(1) */ |
| 1188 | p->p_pctcpu = (p->p_pctcpu * ccpu) >> FSHIFT; |
| 1189 | |
| 1190 | if (__predict_false(runtm < 0)) { |
| 1191 | if (!backwards) { |
| 1192 | backwards = true; |
| 1193 | printf("WARNING: negative runtime; " |
| 1194 | "monotonic clock has gone backwards\n" ); |
| 1195 | } |
| 1196 | mutex_exit(p->p_lock); |
| 1197 | continue; |
| 1198 | } |
| 1199 | |
| 1200 | /* |
| 1201 | * Check if the process exceeds its CPU resource allocation. |
| 1202 | * If over the hard limit, kill it with SIGKILL. |
| 1203 | * If over the soft limit, send SIGXCPU and raise |
| 1204 | * the soft limit a little. |
| 1205 | */ |
| 1206 | rlim = &p->p_rlimit[RLIMIT_CPU]; |
| 1207 | sig = 0; |
| 1208 | if (__predict_false(runtm >= rlim->rlim_cur)) { |
| 1209 | if (runtm >= rlim->rlim_max) { |
| 1210 | sig = SIGKILL; |
| 1211 | log(LOG_NOTICE, "pid %d is killed: %s\n" , |
| 1212 | p->p_pid, "exceeded RLIMIT_CPU" ); |
| 1213 | uprintf("pid %d, command %s, is killed: %s\n" , |
| 1214 | p->p_pid, p->p_comm, |
| 1215 | "exceeded RLIMIT_CPU" ); |
| 1216 | } else { |
| 1217 | sig = SIGXCPU; |
| 1218 | if (rlim->rlim_cur < rlim->rlim_max) |
| 1219 | rlim->rlim_cur += 5; |
| 1220 | } |
| 1221 | } |
| 1222 | mutex_exit(p->p_lock); |
| 1223 | if (__predict_false(sig)) { |
| 1224 | KASSERT((p->p_flag & PK_SYSTEM) == 0); |
| 1225 | psignal(p, sig); |
| 1226 | } |
| 1227 | } |
| 1228 | mutex_exit(proc_lock); |
| 1229 | |
| 1230 | /* Load average calculation. */ |
| 1231 | if (__predict_false(lavg_count == 0)) { |
| 1232 | int i; |
| 1233 | CTASSERT(__arraycount(cexp) == __arraycount(avg->ldavg)); |
| 1234 | for (i = 0; i < __arraycount(cexp); i++) { |
| 1235 | avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + |
| 1236 | nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; |
| 1237 | } |
| 1238 | } |
| 1239 | |
| 1240 | /* Lightning bolt. */ |
| 1241 | cv_broadcast(&lbolt); |
| 1242 | } |
| 1243 | |