| 1 | /* |
| 2 | * Copyright (c) 1999 Peter Wemm <peter@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 | * 2. Redistributions in binary form must reproduce the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer in the |
| 12 | * documentation and/or other materials provided with the distribution. |
| 13 | * |
| 14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
| 15 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 16 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 17 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| 18 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 19 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 20 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 21 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 22 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 23 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 24 | * SUCH DAMAGE. |
| 25 | */ |
| 26 | |
| 27 | #include <sys/param.h> |
| 28 | #include <sys/systm.h> |
| 29 | #include <sys/kernel.h> |
| 30 | #include <sys/lock.h> |
| 31 | #include <sys/queue.h> |
| 32 | #include <sys/proc.h> |
| 33 | #include <sys/rtprio.h> |
| 34 | #include <sys/uio.h> |
| 35 | #include <sys/sysctl.h> |
| 36 | #include <sys/resourcevar.h> |
| 37 | #include <sys/spinlock.h> |
| 38 | #include <machine/cpu.h> |
| 39 | #include <machine/smp.h> |
| 40 | |
| 41 | #include <sys/thread2.h> |
| 42 | #include <sys/spinlock2.h> |
| 43 | #include <sys/mplock2.h> |
| 44 | |
| 45 | /* |
| 46 | * Priorities. Note that with 32 run queues per scheduler each queue |
| 47 | * represents four priority levels. |
| 48 | */ |
| 49 | |
| 50 | #define MAXPRI 128 |
| 51 | #define PRIMASK (MAXPRI - 1) |
| 52 | #define PRIBASE_REALTIME 0 |
| 53 | #define PRIBASE_NORMAL MAXPRI |
| 54 | #define PRIBASE_IDLE (MAXPRI * 2) |
| 55 | #define PRIBASE_THREAD (MAXPRI * 3) |
| 56 | #define PRIBASE_NULL (MAXPRI * 4) |
| 57 | |
| 58 | #define NQS 32 /* 32 run queues. */ |
| 59 | #define PPQ (MAXPRI / NQS) /* priorities per queue */ |
| 60 | #define PPQMASK (PPQ - 1) |
| 61 | |
| 62 | /* |
| 63 | * NICEPPQ - number of nice units per priority queue |
| 64 | * |
| 65 | * ESTCPUPPQ - number of estcpu units per priority queue |
| 66 | * ESTCPUMAX - number of estcpu units |
| 67 | */ |
| 68 | #define NICEPPQ 2 |
| 69 | #define ESTCPUPPQ 512 |
| 70 | #define ESTCPUMAX (ESTCPUPPQ * NQS) |
| 71 | #define BATCHMAX (ESTCPUFREQ * 30) |
| 72 | #define PRIO_RANGE (PRIO_MAX - PRIO_MIN + 1) |
| 73 | |
| 74 | #define ESTCPULIM(v) min((v), ESTCPUMAX) |
| 75 | |
| 76 | TAILQ_HEAD(rq, lwp); |
| 77 | |
| 78 | #define lwp_priority lwp_usdata.bsd4.priority |
| 79 | #define lwp_rqindex lwp_usdata.bsd4.rqindex |
| 80 | #define lwp_estcpu lwp_usdata.bsd4.estcpu |
| 81 | #define lwp_batch lwp_usdata.bsd4.batch |
| 82 | #define lwp_rqtype lwp_usdata.bsd4.rqtype |
| 83 | |
| 84 | static void bsd4_acquire_curproc(struct lwp *lp); |
| 85 | static void bsd4_release_curproc(struct lwp *lp); |
| 86 | static void bsd4_select_curproc(globaldata_t gd); |
| 87 | static void bsd4_setrunqueue(struct lwp *lp); |
| 88 | static void bsd4_schedulerclock(struct lwp *lp, sysclock_t period, |
| 89 | sysclock_t cpstamp); |
| 90 | static void bsd4_recalculate_estcpu(struct lwp *lp); |
| 91 | static void bsd4_resetpriority(struct lwp *lp); |
| 92 | static void bsd4_forking(struct lwp *plp, struct lwp *lp); |
| 93 | static void bsd4_exiting(struct lwp *lp, struct proc *); |
| 94 | static void bsd4_yield(struct lwp *lp); |
| 95 | |
| 96 | #ifdef SMP |
| 97 | static void need_user_resched_remote(void *dummy); |
| 98 | #endif |
| 99 | static struct lwp *chooseproc_locked(struct lwp *chklp); |
| 100 | static void bsd4_remrunqueue_locked(struct lwp *lp); |
| 101 | static void bsd4_setrunqueue_locked(struct lwp *lp); |
| 102 | |
| 103 | struct usched usched_bsd4 = { |
| 104 | { NULL }, |
| 105 | "bsd4", "Original DragonFly Scheduler", |
| 106 | NULL, /* default registration */ |
| 107 | NULL, /* default deregistration */ |
| 108 | bsd4_acquire_curproc, |
| 109 | bsd4_release_curproc, |
| 110 | bsd4_setrunqueue, |
| 111 | bsd4_schedulerclock, |
| 112 | bsd4_recalculate_estcpu, |
| 113 | bsd4_resetpriority, |
| 114 | bsd4_forking, |
| 115 | bsd4_exiting, |
| 116 | NULL, /* setcpumask not supported */ |
| 117 | bsd4_yield |
| 118 | }; |
| 119 | |
| 120 | struct usched_bsd4_pcpu { |
| 121 | struct thread helper_thread; |
| 122 | short rrcount; |
| 123 | short upri; |
| 124 | struct lwp *uschedcp; |
| 125 | }; |
| 126 | |
| 127 | typedef struct usched_bsd4_pcpu *bsd4_pcpu_t; |
| 128 | |
| 129 | /* |
| 130 | * We have NQS (32) run queues per scheduling class. For the normal |
| 131 | * class, there are 128 priorities scaled onto these 32 queues. New |
| 132 | * processes are added to the last entry in each queue, and processes |
| 133 | * are selected for running by taking them from the head and maintaining |
| 134 | * a simple FIFO arrangement. Realtime and Idle priority processes have |
| 135 | * and explicit 0-31 priority which maps directly onto their class queue |
| 136 | * index. When a queue has something in it, the corresponding bit is |
| 137 | * set in the queuebits variable, allowing a single read to determine |
| 138 | * the state of all 32 queues and then a ffs() to find the first busy |
| 139 | * queue. |
| 140 | */ |
| 141 | static struct rq bsd4_queues[NQS]; |
| 142 | static struct rq bsd4_rtqueues[NQS]; |
| 143 | static struct rq bsd4_idqueues[NQS]; |
| 144 | static u_int32_t bsd4_queuebits; |
| 145 | static u_int32_t bsd4_rtqueuebits; |
| 146 | static u_int32_t bsd4_idqueuebits; |
| 147 | static cpumask_t bsd4_curprocmask = -1; /* currently running a user process */ |
| 148 | static cpumask_t bsd4_rdyprocmask; /* ready to accept a user process */ |
| 149 | static int bsd4_runqcount; |
| 150 | #ifdef SMP |
| 151 | static volatile int bsd4_scancpu; |
| 152 | #endif |
| 153 | static struct spinlock bsd4_spin; |
| 154 | static struct usched_bsd4_pcpu bsd4_pcpu[MAXCPU]; |
| 155 | |
| 156 | SYSCTL_INT(_debug, OID_AUTO, bsd4_runqcount, CTLFLAG_RD, &bsd4_runqcount, 0, |
| 157 | "Number of run queues"); |
| 158 | #ifdef INVARIANTS |
| 159 | static int usched_nonoptimal; |
| 160 | SYSCTL_INT(_debug, OID_AUTO, usched_nonoptimal, CTLFLAG_RW, |
| 161 | &usched_nonoptimal, 0, "acquire_curproc() was not optimal"); |
| 162 | static int usched_optimal; |
| 163 | SYSCTL_INT(_debug, OID_AUTO, usched_optimal, CTLFLAG_RW, |
| 164 | &usched_optimal, 0, "acquire_curproc() was optimal"); |
| 165 | #endif |
| 166 | static int usched_debug = -1; |
| 167 | SYSCTL_INT(_debug, OID_AUTO, scdebug, CTLFLAG_RW, &usched_debug, 0, |
| 168 | "Print debug information for this pid"); |
| 169 | #ifdef SMP |
| 170 | static int remote_resched_nonaffinity; |
| 171 | static int remote_resched_affinity; |
| 172 | static int choose_affinity; |
| 173 | SYSCTL_INT(_debug, OID_AUTO, remote_resched_nonaffinity, CTLFLAG_RD, |
| 174 | &remote_resched_nonaffinity, 0, "Number of remote rescheds"); |
| 175 | SYSCTL_INT(_debug, OID_AUTO, remote_resched_affinity, CTLFLAG_RD, |
| 176 | &remote_resched_affinity, 0, "Number of remote rescheds"); |
| 177 | SYSCTL_INT(_debug, OID_AUTO, choose_affinity, CTLFLAG_RD, |
| 178 | &choose_affinity, 0, "chooseproc() was smart"); |
| 179 | #endif |
| 180 | |
| 181 | static int usched_bsd4_rrinterval = (ESTCPUFREQ + 9) / 10; |
| 182 | SYSCTL_INT(_kern, OID_AUTO, usched_bsd4_rrinterval, CTLFLAG_RW, |
| 183 | &usched_bsd4_rrinterval, 0, ""); |
| 184 | static int usched_bsd4_decay = 8; |
| 185 | SYSCTL_INT(_kern, OID_AUTO, usched_bsd4_decay, CTLFLAG_RW, |
| 186 | &usched_bsd4_decay, 0, "Extra decay when not running"); |
| 187 | static int usched_bsd4_batch_time = 10; |
| 188 | SYSCTL_INT(_kern, OID_AUTO, usched_bsd4_batch_time, CTLFLAG_RW, |
| 189 | &usched_bsd4_batch_time, 0, "Minimum batch counter value"); |
| 190 | |
| 191 | /* |
| 192 | * Initialize the run queues at boot time. |
| 193 | */ |
| 194 | static void |
| 195 | rqinit(void *dummy) |
| 196 | { |
| 197 | int i; |
| 198 | |
| 199 | spin_init(&bsd4_spin); |
| 200 | for (i = 0; i < NQS; i++) { |
| 201 | TAILQ_INIT(&bsd4_queues[i]); |
| 202 | TAILQ_INIT(&bsd4_rtqueues[i]); |
| 203 | TAILQ_INIT(&bsd4_idqueues[i]); |
| 204 | } |
| 205 | atomic_clear_cpumask(&bsd4_curprocmask, 1); |
| 206 | } |
| 207 | SYSINIT(runqueue, SI_BOOT2_USCHED, SI_ORDER_FIRST, rqinit, NULL) |
| 208 | |
| 209 | /* |
| 210 | * BSD4_ACQUIRE_CURPROC |
| 211 | * |
| 212 | * This function is called when the kernel intends to return to userland. |
| 213 | * It is responsible for making the thread the current designated userland |
| 214 | * thread for this cpu, blocking if necessary. |
| 215 | * |
| 216 | * The kernel has already depressed our LWKT priority so we must not switch |
| 217 | * until we have either assigned or disposed of the thread. |
| 218 | * |
| 219 | * WARNING! THIS FUNCTION IS ALLOWED TO CAUSE THE CURRENT THREAD TO MIGRATE |
| 220 | * TO ANOTHER CPU! Because most of the kernel assumes that no migration will |
| 221 | * occur, this function is called only under very controlled circumstances. |
| 222 | * |
| 223 | * MPSAFE |
| 224 | */ |
| 225 | static void |
| 226 | bsd4_acquire_curproc(struct lwp *lp) |
| 227 | { |
| 228 | globaldata_t gd; |
| 229 | bsd4_pcpu_t dd; |
| 230 | thread_t td; |
| 231 | #if 0 |
| 232 | struct lwp *olp; |
| 233 | #endif |
| 234 | |
| 235 | /* |
| 236 | * Make sure we aren't sitting on a tsleep queue. |
| 237 | */ |
| 238 | td = lp->lwp_thread; |
| 239 | crit_enter_quick(td); |
| 240 | if (td->td_flags & TDF_TSLEEPQ) |
| 241 | tsleep_remove(td); |
| 242 | bsd4_recalculate_estcpu(lp); |
| 243 | |
| 244 | /* |
| 245 | * If a reschedule was requested give another thread the |
| 246 | * driver's seat. |
| 247 | */ |
| 248 | if (user_resched_wanted()) { |
| 249 | clear_user_resched(); |
| 250 | bsd4_release_curproc(lp); |
| 251 | } |
| 252 | |
| 253 | /* |
| 254 | * Loop until we are the current user thread |
| 255 | */ |
| 256 | gd = mycpu; |
| 257 | dd = &bsd4_pcpu[gd->gd_cpuid]; |
| 258 | |
| 259 | do { |
| 260 | /* |
| 261 | * Process any pending events and higher priority threads. |
| 262 | */ |
| 263 | lwkt_yield(); |
| 264 | |
| 265 | /* |
| 266 | * Become the currently scheduled user thread for this cpu |
| 267 | * if we can do so trivially. |
| 268 | * |
| 269 | * We can steal another thread's current thread designation |
| 270 | * on this cpu since if we are running that other thread |
| 271 | * must not be, so we can safely deschedule it. |
| 272 | */ |
| 273 | if (dd->uschedcp == lp) { |
| 274 | /* |
| 275 | * We are already the current lwp (hot path). |
| 276 | */ |
| 277 | dd->upri = lp->lwp_priority; |
| 278 | } else if (dd->uschedcp == NULL) { |
| 279 | /* |
| 280 | * We can trivially become the current lwp. |
| 281 | */ |
| 282 | atomic_set_cpumask(&bsd4_curprocmask, gd->gd_cpumask); |
| 283 | dd->uschedcp = lp; |
| 284 | dd->upri = lp->lwp_priority; |
| 285 | } else if (dd->upri > lp->lwp_priority) { |
| 286 | /* |
| 287 | * We can steal the current cpu's lwp designation |
| 288 | * away simply by replacing it. The other thread |
| 289 | * will stall when it tries to return to userland. |
| 290 | */ |
| 291 | dd->uschedcp = lp; |
| 292 | dd->upri = lp->lwp_priority; |
| 293 | /* |
| 294 | lwkt_deschedule(olp->lwp_thread); |
| 295 | bsd4_setrunqueue(olp); |
| 296 | */ |
| 297 | } else { |
| 298 | /* |
| 299 | * We cannot become the current lwp, place the lp |
| 300 | * on the bsd4 run-queue and deschedule ourselves. |
| 301 | * |
| 302 | * When we are reactivated we will have another |
| 303 | * chance. |
| 304 | */ |
| 305 | lwkt_deschedule(lp->lwp_thread); |
| 306 | bsd4_setrunqueue(lp); |
| 307 | lwkt_switch(); |
| 308 | /* |
| 309 | * Reload after a switch or setrunqueue/switch possibly |
| 310 | * moved us to another cpu. |
| 311 | */ |
| 312 | gd = mycpu; |
| 313 | dd = &bsd4_pcpu[gd->gd_cpuid]; |
| 314 | } |
| 315 | } while (dd->uschedcp != lp); |
| 316 | |
| 317 | crit_exit_quick(td); |
| 318 | KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0); |
| 319 | } |
| 320 | |
| 321 | /* |
| 322 | * BSD4_RELEASE_CURPROC |
| 323 | * |
| 324 | * This routine detaches the current thread from the userland scheduler, |
| 325 | * usually because the thread needs to run or block in the kernel (at |
| 326 | * kernel priority) for a while. |
| 327 | * |
| 328 | * This routine is also responsible for selecting a new thread to |
| 329 | * make the current thread. |
| 330 | * |
| 331 | * NOTE: This implementation differs from the dummy example in that |
| 332 | * bsd4_select_curproc() is able to select the current process, whereas |
| 333 | * dummy_select_curproc() is not able to select the current process. |
| 334 | * This means we have to NULL out uschedcp. |
| 335 | * |
| 336 | * Additionally, note that we may already be on a run queue if releasing |
| 337 | * via the lwkt_switch() in bsd4_setrunqueue(). |
| 338 | * |
| 339 | * MPSAFE |
| 340 | */ |
| 341 | static void |
| 342 | bsd4_release_curproc(struct lwp *lp) |
| 343 | { |
| 344 | globaldata_t gd = mycpu; |
| 345 | bsd4_pcpu_t dd = &bsd4_pcpu[gd->gd_cpuid]; |
| 346 | |
| 347 | if (dd->uschedcp == lp) { |
| 348 | crit_enter(); |
| 349 | KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0); |
| 350 | dd->uschedcp = NULL; /* don't let lp be selected */ |
| 351 | dd->upri = PRIBASE_NULL; |
| 352 | atomic_clear_cpumask(&bsd4_curprocmask, gd->gd_cpumask); |
| 353 | bsd4_select_curproc(gd); |
| 354 | crit_exit(); |
| 355 | } |
| 356 | } |
| 357 | |
| 358 | /* |
| 359 | * BSD4_SELECT_CURPROC |
| 360 | * |
| 361 | * Select a new current process for this cpu and clear any pending user |
| 362 | * reschedule request. The cpu currently has no current process. |
| 363 | * |
| 364 | * This routine is also responsible for equal-priority round-robining, |
| 365 | * typically triggered from bsd4_schedulerclock(). In our dummy example |
| 366 | * all the 'user' threads are LWKT scheduled all at once and we just |
| 367 | * call lwkt_switch(). |
| 368 | * |
| 369 | * The calling process is not on the queue and cannot be selected. |
| 370 | * |
| 371 | * MPSAFE |
| 372 | */ |
| 373 | static |
| 374 | void |
| 375 | bsd4_select_curproc(globaldata_t gd) |
| 376 | { |
| 377 | bsd4_pcpu_t dd = &bsd4_pcpu[gd->gd_cpuid]; |
| 378 | struct lwp *nlp; |
| 379 | int cpuid = gd->gd_cpuid; |
| 380 | |
| 381 | crit_enter_gd(gd); |
| 382 | |
| 383 | spin_lock(&bsd4_spin); |
| 384 | if ((nlp = chooseproc_locked(dd->uschedcp)) != NULL) { |
| 385 | atomic_set_cpumask(&bsd4_curprocmask, CPUMASK(cpuid)); |
| 386 | dd->upri = nlp->lwp_priority; |
| 387 | dd->uschedcp = nlp; |
| 388 | spin_unlock(&bsd4_spin); |
| 389 | #ifdef SMP |
| 390 | lwkt_acquire(nlp->lwp_thread); |
| 391 | #endif |
| 392 | lwkt_schedule(nlp->lwp_thread); |
| 393 | } else { |
| 394 | spin_unlock(&bsd4_spin); |
| 395 | } |
| 396 | #if 0 |
| 397 | } else if (bsd4_runqcount && (bsd4_rdyprocmask & CPUMASK(cpuid))) { |
| 398 | atomic_clear_cpumask(&bsd4_rdyprocmask, CPUMASK(cpuid)); |
| 399 | spin_unlock(&bsd4_spin); |
| 400 | lwkt_schedule(&dd->helper_thread); |
| 401 | } else { |
| 402 | spin_unlock(&bsd4_spin); |
| 403 | } |
| 404 | #endif |
| 405 | crit_exit_gd(gd); |
| 406 | } |
| 407 | |
| 408 | /* |
| 409 | * BSD4_SETRUNQUEUE |
| 410 | * |
| 411 | * Place the specified lwp on the user scheduler's run queue. This routine |
| 412 | * must be called with the thread descheduled. The lwp must be runnable. |
| 413 | * |
| 414 | * The thread may be the current thread as a special case. |
| 415 | * |
| 416 | * MPSAFE |
| 417 | */ |
| 418 | static void |
| 419 | bsd4_setrunqueue(struct lwp *lp) |
| 420 | { |
| 421 | globaldata_t gd; |
| 422 | bsd4_pcpu_t dd; |
| 423 | #ifdef SMP |
| 424 | int cpuid; |
| 425 | cpumask_t mask; |
| 426 | cpumask_t tmpmask; |
| 427 | #endif |
| 428 | |
| 429 | /* |
| 430 | * First validate the process state relative to the current cpu. |
| 431 | * We don't need the spinlock for this, just a critical section. |
| 432 | * We are in control of the process. |
| 433 | */ |
| 434 | crit_enter(); |
| 435 | KASSERT(lp->lwp_stat == LSRUN, ("setrunqueue: lwp not LSRUN")); |
| 436 | KASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0, |
| 437 | ("lwp %d/%d already on runq! flag %08x/%08x", lp->lwp_proc->p_pid, |
| 438 | lp->lwp_tid, lp->lwp_proc->p_flags, lp->lwp_flags)); |
| 439 | KKASSERT((lp->lwp_thread->td_flags & TDF_RUNQ) == 0); |
| 440 | |
| 441 | /* |
| 442 | * Note: gd and dd are relative to the target thread's last cpu, |
| 443 | * NOT our current cpu. |
| 444 | */ |
| 445 | gd = lp->lwp_thread->td_gd; |
| 446 | dd = &bsd4_pcpu[gd->gd_cpuid]; |
| 447 | |
| 448 | /* |
| 449 | * This process is not supposed to be scheduled anywhere or assigned |
| 450 | * as the current process anywhere. Assert the condition. |
| 451 | */ |
| 452 | KKASSERT(dd->uschedcp != lp); |
| 453 | |
| 454 | #ifndef SMP |
| 455 | /* |
| 456 | * If we are not SMP we do not have a scheduler helper to kick |
| 457 | * and must directly activate the process if none are scheduled. |
| 458 | * |
| 459 | * This is really only an issue when bootstrapping init since |
| 460 | * the caller in all other cases will be a user process, and |
| 461 | * even if released (dd->uschedcp == NULL), that process will |
| 462 | * kickstart the scheduler when it returns to user mode from |
| 463 | * the kernel. |
| 464 | */ |
| 465 | if (dd->uschedcp == NULL) { |
| 466 | atomic_set_cpumask(&bsd4_curprocmask, gd->gd_cpumask); |
| 467 | dd->uschedcp = lp; |
| 468 | dd->upri = lp->lwp_priority; |
| 469 | lwkt_schedule(lp->lwp_thread); |
| 470 | crit_exit(); |
| 471 | return; |
| 472 | } |
| 473 | #endif |
| 474 | |
| 475 | #ifdef SMP |
| 476 | /* |
| 477 | * XXX fixme. Could be part of a remrunqueue/setrunqueue |
| 478 | * operation when the priority is recalculated, so TDF_MIGRATING |
| 479 | * may already be set. |
| 480 | */ |
| 481 | if ((lp->lwp_thread->td_flags & TDF_MIGRATING) == 0) |
| 482 | lwkt_giveaway(lp->lwp_thread); |
| 483 | #endif |
| 484 | |
| 485 | /* |
| 486 | * We lose control of lp the moment we release the spinlock after |
| 487 | * having placed lp on the queue. i.e. another cpu could pick it |
| 488 | * up and it could exit, or its priority could be further adjusted, |
| 489 | * or something like that. |
| 490 | */ |
| 491 | spin_lock(&bsd4_spin); |
| 492 | bsd4_setrunqueue_locked(lp); |
| 493 | |
| 494 | #ifdef SMP |
| 495 | /* |
| 496 | * Kick the scheduler helper on one of the other cpu's |
| 497 | * and request a reschedule if appropriate. |
| 498 | * |
| 499 | * NOTE: We check all cpus whos rdyprocmask is set. First we |
| 500 | * look for cpus without designated lps, then we look for |
| 501 | * cpus with designated lps with a worse priority than our |
| 502 | * process. |
| 503 | */ |
| 504 | ++bsd4_scancpu; |
| 505 | cpuid = (bsd4_scancpu & 0xFFFF) % ncpus; |
| 506 | mask = ~bsd4_curprocmask & bsd4_rdyprocmask & lp->lwp_cpumask & |
| 507 | smp_active_mask & usched_global_cpumask; |
| 508 | |
| 509 | while (mask) { |
| 510 | tmpmask = ~(CPUMASK(cpuid) - 1); |
| 511 | if (mask & tmpmask) |
| 512 | cpuid = BSFCPUMASK(mask & tmpmask); |
| 513 | else |
| 514 | cpuid = BSFCPUMASK(mask); |
| 515 | gd = globaldata_find(cpuid); |
| 516 | dd = &bsd4_pcpu[cpuid]; |
| 517 | |
| 518 | if ((dd->upri & ~PPQMASK) >= (lp->lwp_priority & ~PPQMASK)) |
| 519 | goto found; |
| 520 | mask &= ~CPUMASK(cpuid); |
| 521 | } |
| 522 | |
| 523 | /* |
| 524 | * Then cpus which might have a currently running lp |
| 525 | */ |
| 526 | mask = bsd4_curprocmask & bsd4_rdyprocmask & |
| 527 | lp->lwp_cpumask & smp_active_mask & usched_global_cpumask; |
| 528 | |
| 529 | while (mask) { |
| 530 | tmpmask = ~(CPUMASK(cpuid) - 1); |
| 531 | if (mask & tmpmask) |
| 532 | cpuid = BSFCPUMASK(mask & tmpmask); |
| 533 | else |
| 534 | cpuid = BSFCPUMASK(mask); |
| 535 | gd = globaldata_find(cpuid); |
| 536 | dd = &bsd4_pcpu[cpuid]; |
| 537 | |
| 538 | if ((dd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK)) |
| 539 | goto found; |
| 540 | mask &= ~CPUMASK(cpuid); |
| 541 | } |
| 542 | |
| 543 | /* |
| 544 | * If we cannot find a suitable cpu we reload from bsd4_scancpu |
| 545 | * and round-robin. Other cpus will pickup as they release their |
| 546 | * current lwps or become ready. |
| 547 | * |
| 548 | * Avoid a degenerate system lockup case if usched_global_cpumask |
| 549 | * is set to 0 or otherwise does not cover lwp_cpumask. |
| 550 | * |
| 551 | * We only kick the target helper thread in this case, we do not |
| 552 | * set the user resched flag because |
| 553 | */ |
| 554 | cpuid = (bsd4_scancpu & 0xFFFF) % ncpus; |
| 555 | if ((CPUMASK(cpuid) & usched_global_cpumask) == 0) { |
| 556 | cpuid = 0; |
| 557 | } |
| 558 | gd = globaldata_find(cpuid); |
| 559 | dd = &bsd4_pcpu[cpuid]; |
| 560 | found: |
| 561 | if (gd == mycpu) { |
| 562 | spin_unlock(&bsd4_spin); |
| 563 | if ((dd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK)) { |
| 564 | if (dd->uschedcp == NULL) { |
| 565 | lwkt_schedule(&dd->helper_thread); |
| 566 | } else { |
| 567 | need_user_resched(); |
| 568 | } |
| 569 | } |
| 570 | } else { |
| 571 | atomic_clear_cpumask(&bsd4_rdyprocmask, CPUMASK(cpuid)); |
| 572 | spin_unlock(&bsd4_spin); |
| 573 | if ((dd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK)) |
| 574 | lwkt_send_ipiq(gd, need_user_resched_remote, NULL); |
| 575 | else |
| 576 | lwkt_schedule(&dd->helper_thread); |
| 577 | } |
| 578 | #else |
| 579 | /* |
| 580 | * Request a reschedule if appropriate. |
| 581 | */ |
| 582 | spin_unlock(&bsd4_spin); |
| 583 | if ((dd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK)) { |
| 584 | need_user_resched(); |
| 585 | } |
| 586 | #endif |
| 587 | crit_exit(); |
| 588 | } |
| 589 | |
| 590 | /* |
| 591 | * This routine is called from a systimer IPI. It MUST be MP-safe and |
| 592 | * the BGL IS NOT HELD ON ENTRY. This routine is called at ESTCPUFREQ on |
| 593 | * each cpu. |
| 594 | * |
| 595 | * MPSAFE |
| 596 | */ |
| 597 | static |
| 598 | void |
| 599 | bsd4_schedulerclock(struct lwp *lp, sysclock_t period, sysclock_t cpstamp) |
| 600 | { |
| 601 | globaldata_t gd = mycpu; |
| 602 | bsd4_pcpu_t dd = &bsd4_pcpu[gd->gd_cpuid]; |
| 603 | |
| 604 | /* |
| 605 | * Do we need to round-robin? We round-robin 10 times a second. |
| 606 | * This should only occur for cpu-bound batch processes. |
| 607 | */ |
| 608 | if (++dd->rrcount >= usched_bsd4_rrinterval) { |
| 609 | dd->rrcount = 0; |
| 610 | need_user_resched(); |
| 611 | } |
| 612 | |
| 613 | /* |
| 614 | * Adjust estcpu upward using a real time equivalent calculation. |
| 615 | */ |
| 616 | lp->lwp_estcpu = ESTCPULIM(lp->lwp_estcpu + ESTCPUMAX / ESTCPUFREQ + 1); |
| 617 | |
| 618 | /* |
| 619 | * Spinlocks also hold a critical section so there should not be |
| 620 | * any active. |
| 621 | */ |
| 622 | KKASSERT(gd->gd_spinlocks_wr == 0); |
| 623 | |
| 624 | bsd4_resetpriority(lp); |
| 625 | #if 0 |
| 626 | /* |
| 627 | * if we can't call bsd4_resetpriority for some reason we must call |
| 628 | * need user_resched(). |
| 629 | */ |
| 630 | need_user_resched(); |
| 631 | #endif |
| 632 | } |
| 633 | |
| 634 | /* |
| 635 | * Called from acquire and from kern_synch's one-second timer (one of the |
| 636 | * callout helper threads) with a critical section held. |
| 637 | * |
| 638 | * Decay p_estcpu based on the number of ticks we haven't been running |
| 639 | * and our p_nice. As the load increases each process observes a larger |
| 640 | * number of idle ticks (because other processes are running in them). |
| 641 | * This observation leads to a larger correction which tends to make the |
| 642 | * system more 'batchy'. |
| 643 | * |
| 644 | * Note that no recalculation occurs for a process which sleeps and wakes |
| 645 | * up in the same tick. That is, a system doing thousands of context |
| 646 | * switches per second will still only do serious estcpu calculations |
| 647 | * ESTCPUFREQ times per second. |
| 648 | * |
| 649 | * MPSAFE |
| 650 | */ |
| 651 | static |
| 652 | void |
| 653 | bsd4_recalculate_estcpu(struct lwp *lp) |
| 654 | { |
| 655 | globaldata_t gd = mycpu; |
| 656 | sysclock_t cpbase; |
| 657 | sysclock_t ttlticks; |
| 658 | int estcpu; |
| 659 | int decay_factor; |
| 660 | |
| 661 | /* |
| 662 | * We have to subtract periodic to get the last schedclock |
| 663 | * timeout time, otherwise we would get the upcoming timeout. |
| 664 | * Keep in mind that a process can migrate between cpus and |
| 665 | * while the scheduler clock should be very close, boundary |
| 666 | * conditions could lead to a small negative delta. |
| 667 | */ |
| 668 | cpbase = gd->gd_schedclock.time - gd->gd_schedclock.periodic; |
| 669 | |
| 670 | if (lp->lwp_slptime > 1) { |
| 671 | /* |
| 672 | * Too much time has passed, do a coarse correction. |
| 673 | */ |
| 674 | lp->lwp_estcpu = lp->lwp_estcpu >> 1; |
| 675 | bsd4_resetpriority(lp); |
| 676 | lp->lwp_cpbase = cpbase; |
| 677 | lp->lwp_cpticks = 0; |
| 678 | lp->lwp_batch -= ESTCPUFREQ; |
| 679 | if (lp->lwp_batch < 0) |
| 680 | lp->lwp_batch = 0; |
| 681 | } else if (lp->lwp_cpbase != cpbase) { |
| 682 | /* |
| 683 | * Adjust estcpu if we are in a different tick. Don't waste |
| 684 | * time if we are in the same tick. |
| 685 | * |
| 686 | * First calculate the number of ticks in the measurement |
| 687 | * interval. The ttlticks calculation can wind up 0 due to |
| 688 | * a bug in the handling of lwp_slptime (as yet not found), |
| 689 | * so make sure we do not get a divide by 0 panic. |
| 690 | */ |
| 691 | ttlticks = (cpbase - lp->lwp_cpbase) / |
| 692 | gd->gd_schedclock.periodic; |
| 693 | if (ttlticks < 0) { |
| 694 | ttlticks = 0; |
| 695 | lp->lwp_cpbase = cpbase; |
| 696 | } |
| 697 | if (ttlticks == 0) |
| 698 | return; |
| 699 | updatepcpu(lp, lp->lwp_cpticks, ttlticks); |
| 700 | |
| 701 | /* |
| 702 | * Calculate the percentage of one cpu used factoring in ncpus |
| 703 | * and the load and adjust estcpu. Handle degenerate cases |
| 704 | * by adding 1 to bsd4_runqcount. |
| 705 | * |
| 706 | * estcpu is scaled by ESTCPUMAX. |
| 707 | * |
| 708 | * bsd4_runqcount is the excess number of user processes |
| 709 | * that cannot be immediately scheduled to cpus. We want |
| 710 | * to count these as running to avoid range compression |
| 711 | * in the base calculation (which is the actual percentage |
| 712 | * of one cpu used). |
| 713 | */ |
| 714 | estcpu = (lp->lwp_cpticks * ESTCPUMAX) * |
| 715 | (bsd4_runqcount + ncpus) / (ncpus * ttlticks); |
| 716 | |
| 717 | /* |
| 718 | * If estcpu is > 50% we become more batch-like |
| 719 | * If estcpu is <= 50% we become less batch-like |
| 720 | * |
| 721 | * It takes 30 cpu seconds to traverse the entire range. |
| 722 | */ |
| 723 | if (estcpu > ESTCPUMAX / 2) { |
| 724 | lp->lwp_batch += ttlticks; |
| 725 | if (lp->lwp_batch > BATCHMAX) |
| 726 | lp->lwp_batch = BATCHMAX; |
| 727 | } else { |
| 728 | lp->lwp_batch -= ttlticks; |
| 729 | if (lp->lwp_batch < 0) |
| 730 | lp->lwp_batch = 0; |
| 731 | } |
| 732 | |
| 733 | if (usched_debug == lp->lwp_proc->p_pid) { |
| 734 | kprintf("pid %d lwp %p estcpu %3d %3d bat %d cp %d/%d", |
| 735 | lp->lwp_proc->p_pid, lp, |
| 736 | estcpu, lp->lwp_estcpu, |
| 737 | lp->lwp_batch, |
| 738 | lp->lwp_cpticks, ttlticks); |
| 739 | } |
| 740 | |
| 741 | /* |
| 742 | * Adjust lp->lwp_esetcpu. The decay factor determines how |
| 743 | * quickly lwp_estcpu collapses to its realtime calculation. |
| 744 | * A slower collapse gives us a more accurate number but |
| 745 | * can cause a cpu hog to eat too much cpu before the |
| 746 | * scheduler decides to downgrade it. |
| 747 | * |
| 748 | * NOTE: p_nice is accounted for in bsd4_resetpriority(), |
| 749 | * and not here, but we must still ensure that a |
| 750 | * cpu-bound nice -20 process does not completely |
| 751 | * override a cpu-bound nice +20 process. |
| 752 | * |
| 753 | * NOTE: We must use ESTCPULIM() here to deal with any |
| 754 | * overshoot. |
| 755 | */ |
| 756 | decay_factor = usched_bsd4_decay; |
| 757 | if (decay_factor < 1) |
| 758 | decay_factor = 1; |
| 759 | if (decay_factor > 1024) |
| 760 | decay_factor = 1024; |
| 761 | |
| 762 | lp->lwp_estcpu = ESTCPULIM( |
| 763 | (lp->lwp_estcpu * decay_factor + estcpu) / |
| 764 | (decay_factor + 1)); |
| 765 | |
| 766 | if (usched_debug == lp->lwp_proc->p_pid) |
| 767 | kprintf(" finalestcpu %d\n", lp->lwp_estcpu); |
| 768 | bsd4_resetpriority(lp); |
| 769 | lp->lwp_cpbase += ttlticks * gd->gd_schedclock.periodic; |
| 770 | lp->lwp_cpticks = 0; |
| 771 | } |
| 772 | } |
| 773 | |
| 774 | /* |
| 775 | * Compute the priority of a process when running in user mode. |
| 776 | * Arrange to reschedule if the resulting priority is better |
| 777 | * than that of the current process. |
| 778 | * |
| 779 | * This routine may be called with any process. |
| 780 | * |
| 781 | * This routine is called by fork1() for initial setup with the process |
| 782 | * of the run queue, and also may be called normally with the process on or |
| 783 | * off the run queue. |
| 784 | * |
| 785 | * MPSAFE |
| 786 | */ |
| 787 | static void |
| 788 | bsd4_resetpriority(struct lwp *lp) |
| 789 | { |
| 790 | bsd4_pcpu_t dd; |
| 791 | int newpriority; |
| 792 | u_short newrqtype; |
| 793 | int reschedcpu; |
| 794 | int checkpri; |
| 795 | int estcpu; |
| 796 | |
| 797 | /* |
| 798 | * Calculate the new priority and queue type |
| 799 | */ |
| 800 | crit_enter(); |
| 801 | spin_lock(&bsd4_spin); |
| 802 | |
| 803 | newrqtype = lp->lwp_rtprio.type; |
| 804 | |
| 805 | switch(newrqtype) { |
| 806 | case RTP_PRIO_REALTIME: |
| 807 | case RTP_PRIO_FIFO: |
| 808 | newpriority = PRIBASE_REALTIME + |
| 809 | (lp->lwp_rtprio.prio & PRIMASK); |
| 810 | break; |
| 811 | case RTP_PRIO_NORMAL: |
| 812 | /* |
| 813 | * Detune estcpu based on batchiness. lwp_batch ranges |
| 814 | * from 0 to BATCHMAX. Limit estcpu for the sake of |
| 815 | * the priority calculation to between 50% and 100%. |
| 816 | */ |
| 817 | estcpu = lp->lwp_estcpu * (lp->lwp_batch + BATCHMAX) / |
| 818 | (BATCHMAX * 2); |
| 819 | |
| 820 | /* |
| 821 | * p_nice piece Adds (0-40) * 2 0-80 |
| 822 | * estcpu Adds 16384 * 4 / 512 0-128 |
| 823 | */ |
| 824 | newpriority = (lp->lwp_proc->p_nice - PRIO_MIN) * PPQ / NICEPPQ; |
| 825 | newpriority += estcpu * PPQ / ESTCPUPPQ; |
| 826 | newpriority = newpriority * MAXPRI / (PRIO_RANGE * PPQ / |
| 827 | NICEPPQ + ESTCPUMAX * PPQ / ESTCPUPPQ); |
| 828 | newpriority = PRIBASE_NORMAL + (newpriority & PRIMASK); |
| 829 | break; |
| 830 | case RTP_PRIO_IDLE: |
| 831 | newpriority = PRIBASE_IDLE + (lp->lwp_rtprio.prio & PRIMASK); |
| 832 | break; |
| 833 | case RTP_PRIO_THREAD: |
| 834 | newpriority = PRIBASE_THREAD + (lp->lwp_rtprio.prio & PRIMASK); |
| 835 | break; |
| 836 | default: |
| 837 | panic("Bad RTP_PRIO %d", newrqtype); |
| 838 | /* NOT REACHED */ |
| 839 | } |
| 840 | |
| 841 | /* |
| 842 | * The newpriority incorporates the queue type so do a simple masked |
| 843 | * check to determine if the process has moved to another queue. If |
| 844 | * it has, and it is currently on a run queue, then move it. |
| 845 | */ |
| 846 | if ((lp->lwp_priority ^ newpriority) & ~PPQMASK) { |
| 847 | lp->lwp_priority = newpriority; |
| 848 | if (lp->lwp_mpflags & LWP_MP_ONRUNQ) { |
| 849 | bsd4_remrunqueue_locked(lp); |
| 850 | lp->lwp_rqtype = newrqtype; |
| 851 | lp->lwp_rqindex = (newpriority & PRIMASK) / PPQ; |
| 852 | bsd4_setrunqueue_locked(lp); |
| 853 | checkpri = 1; |
| 854 | } else { |
| 855 | lp->lwp_rqtype = newrqtype; |
| 856 | lp->lwp_rqindex = (newpriority & PRIMASK) / PPQ; |
| 857 | checkpri = 0; |
| 858 | } |
| 859 | reschedcpu = lp->lwp_thread->td_gd->gd_cpuid; |
| 860 | } else { |
| 861 | lp->lwp_priority = newpriority; |
| 862 | reschedcpu = -1; |
| 863 | checkpri = 1; |
| 864 | } |
| 865 | |
| 866 | /* |
| 867 | * Determine if we need to reschedule the target cpu. This only |
| 868 | * occurs if the LWP is already on a scheduler queue, which means |
| 869 | * that idle cpu notification has already occured. At most we |
| 870 | * need only issue a need_user_resched() on the appropriate cpu. |
| 871 | * |
| 872 | * The LWP may be owned by a CPU different from the current one, |
| 873 | * in which case dd->uschedcp may be modified without an MP lock |
| 874 | * or a spinlock held. The worst that happens is that the code |
| 875 | * below causes a spurious need_user_resched() on the target CPU |
| 876 | * and dd->pri to be wrong for a short period of time, both of |
| 877 | * which are harmless. |
| 878 | * |
| 879 | * If checkpri is 0 we are adjusting the priority of the current |
| 880 | * process, possibly higher (less desireable), so ignore the upri |
| 881 | * check which will fail in that case. |
| 882 | */ |
| 883 | if (reschedcpu >= 0) { |
| 884 | dd = &bsd4_pcpu[reschedcpu]; |
| 885 | if ((bsd4_rdyprocmask & CPUMASK(reschedcpu)) && |
| 886 | (checkpri == 0 || |
| 887 | (dd->upri & ~PRIMASK) > (lp->lwp_priority & ~PRIMASK))) { |
| 888 | #ifdef SMP |
| 889 | if (reschedcpu == mycpu->gd_cpuid) { |
| 890 | spin_unlock(&bsd4_spin); |
| 891 | need_user_resched(); |
| 892 | } else { |
| 893 | spin_unlock(&bsd4_spin); |
| 894 | atomic_clear_cpumask(&bsd4_rdyprocmask, |
| 895 | CPUMASK(reschedcpu)); |
| 896 | lwkt_send_ipiq(lp->lwp_thread->td_gd, |
| 897 | need_user_resched_remote, NULL); |
| 898 | } |
| 899 | #else |
| 900 | spin_unlock(&bsd4_spin); |
| 901 | need_user_resched(); |
| 902 | #endif |
| 903 | } else { |
| 904 | spin_unlock(&bsd4_spin); |
| 905 | } |
| 906 | } else { |
| 907 | spin_unlock(&bsd4_spin); |
| 908 | } |
| 909 | crit_exit(); |
| 910 | } |
| 911 | |
| 912 | /* |
| 913 | * MPSAFE |
| 914 | */ |
| 915 | static |
| 916 | void |
| 917 | bsd4_yield(struct lwp *lp) |
| 918 | { |
| 919 | #if 0 |
| 920 | /* FUTURE (or something similar) */ |
| 921 | switch(lp->lwp_rqtype) { |
| 922 | case RTP_PRIO_NORMAL: |
| 923 | lp->lwp_estcpu = ESTCPULIM(lp->lwp_estcpu + ESTCPUINCR); |
| 924 | break; |
| 925 | default: |
| 926 | break; |
| 927 | } |
| 928 | #endif |
| 929 | need_user_resched(); |
| 930 | } |
| 931 | |
| 932 | /* |
| 933 | * Called from fork1() when a new child process is being created. |
| 934 | * |
| 935 | * Give the child process an initial estcpu that is more batch then |
| 936 | * its parent and dock the parent for the fork (but do not |
| 937 | * reschedule the parent). This comprises the main part of our batch |
| 938 | * detection heuristic for both parallel forking and sequential execs. |
| 939 | * |
| 940 | * XXX lwp should be "spawning" instead of "forking" |
| 941 | * |
| 942 | * MPSAFE |
| 943 | */ |
| 944 | static void |
| 945 | bsd4_forking(struct lwp *plp, struct lwp *lp) |
| 946 | { |
| 947 | /* |
| 948 | * Put the child 4 queue slots (out of 32) higher than the parent |
| 949 | * (less desireable than the parent). |
| 950 | */ |
| 951 | lp->lwp_estcpu = ESTCPULIM(plp->lwp_estcpu + ESTCPUPPQ * 4); |
| 952 | |
| 953 | /* |
| 954 | * The batch status of children always starts out centerline |
| 955 | * and will inch-up or inch-down as appropriate. It takes roughly |
| 956 | * ~15 seconds of >50% cpu to hit the limit. |
| 957 | */ |
| 958 | lp->lwp_batch = BATCHMAX / 2; |
| 959 | |
| 960 | /* |
| 961 | * Dock the parent a cost for the fork, protecting us from fork |
| 962 | * bombs. If the parent is forking quickly make the child more |
| 963 | * batchy. |
| 964 | */ |
| 965 | plp->lwp_estcpu = ESTCPULIM(plp->lwp_estcpu + ESTCPUPPQ / 16); |
| 966 | } |
| 967 | |
| 968 | /* |
| 969 | * Called when a parent waits for a child. |
| 970 | * |
| 971 | * MPSAFE |
| 972 | */ |
| 973 | static void |
| 974 | bsd4_exiting(struct lwp *lp, struct proc *child_proc) |
| 975 | { |
| 976 | } |
| 977 | |
| 978 | /* |
| 979 | * chooseproc() is called when a cpu needs a user process to LWKT schedule, |
| 980 | * it selects a user process and returns it. If chklp is non-NULL and chklp |
| 981 | * has a better or equal priority then the process that would otherwise be |
| 982 | * chosen, NULL is returned. |
| 983 | * |
| 984 | * Until we fix the RUNQ code the chklp test has to be strict or we may |
| 985 | * bounce between processes trying to acquire the current process designation. |
| 986 | * |
| 987 | * MPSAFE - must be called with bsd4_spin exclusive held. The spinlock is |
| 988 | * left intact through the entire routine. |
| 989 | */ |
| 990 | static |
| 991 | struct lwp * |
| 992 | chooseproc_locked(struct lwp *chklp) |
| 993 | { |
| 994 | struct lwp *lp; |
| 995 | struct rq *q; |
| 996 | u_int32_t *which, *which2; |
| 997 | u_int32_t pri; |
| 998 | u_int32_t rtqbits; |
| 999 | u_int32_t tsqbits; |
| 1000 | u_int32_t idqbits; |
| 1001 | cpumask_t cpumask; |
| 1002 | |
| 1003 | rtqbits = bsd4_rtqueuebits; |
| 1004 | tsqbits = bsd4_queuebits; |
| 1005 | idqbits = bsd4_idqueuebits; |
| 1006 | cpumask = mycpu->gd_cpumask; |
| 1007 | |
| 1008 | #ifdef SMP |
| 1009 | again: |
| 1010 | #endif |
| 1011 | if (rtqbits) { |
| 1012 | pri = bsfl(rtqbits); |
| 1013 | q = &bsd4_rtqueues[pri]; |
| 1014 | which = &bsd4_rtqueuebits; |
| 1015 | which2 = &rtqbits; |
| 1016 | } else if (tsqbits) { |
| 1017 | pri = bsfl(tsqbits); |
| 1018 | q = &bsd4_queues[pri]; |
| 1019 | which = &bsd4_queuebits; |
| 1020 | which2 = &tsqbits; |
| 1021 | } else if (idqbits) { |
| 1022 | pri = bsfl(idqbits); |
| 1023 | q = &bsd4_idqueues[pri]; |
| 1024 | which = &bsd4_idqueuebits; |
| 1025 | which2 = &idqbits; |
| 1026 | } else { |
| 1027 | return NULL; |
| 1028 | } |
| 1029 | lp = TAILQ_FIRST(q); |
| 1030 | KASSERT(lp, ("chooseproc: no lwp on busy queue")); |
| 1031 | |
| 1032 | #ifdef SMP |
| 1033 | while ((lp->lwp_cpumask & cpumask) == 0) { |
| 1034 | lp = TAILQ_NEXT(lp, lwp_procq); |
| 1035 | if (lp == NULL) { |
| 1036 | *which2 &= ~(1 << pri); |
| 1037 | goto again; |
| 1038 | } |
| 1039 | } |
| 1040 | #endif |
| 1041 | |
| 1042 | /* |
| 1043 | * If the passed lwp <chklp> is reasonably close to the selected |
| 1044 | * lwp <lp>, return NULL (indicating that <chklp> should be kept). |
| 1045 | * |
| 1046 | * Note that we must error on the side of <chklp> to avoid bouncing |
| 1047 | * between threads in the acquire code. |
| 1048 | */ |
| 1049 | if (chklp) { |
| 1050 | if (chklp->lwp_priority < lp->lwp_priority + PPQ) |
| 1051 | return(NULL); |
| 1052 | } |
| 1053 | |
| 1054 | #ifdef SMP |
| 1055 | /* |
| 1056 | * If the chosen lwp does not reside on this cpu spend a few |
| 1057 | * cycles looking for a better candidate at the same priority level. |
| 1058 | * This is a fallback check, setrunqueue() tries to wakeup the |
| 1059 | * correct cpu and is our front-line affinity. |
| 1060 | */ |
| 1061 | if (lp->lwp_thread->td_gd != mycpu && |
| 1062 | (chklp = TAILQ_NEXT(lp, lwp_procq)) != NULL |
| 1063 | ) { |
| 1064 | if (chklp->lwp_thread->td_gd == mycpu) { |
| 1065 | ++choose_affinity; |
| 1066 | lp = chklp; |
| 1067 | } |
| 1068 | } |
| 1069 | #endif |
| 1070 | |
| 1071 | TAILQ_REMOVE(q, lp, lwp_procq); |
| 1072 | --bsd4_runqcount; |
| 1073 | if (TAILQ_EMPTY(q)) |
| 1074 | *which &= ~(1 << pri); |
| 1075 | KASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) != 0, ("not on runq6!")); |
| 1076 | atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ); |
| 1077 | return lp; |
| 1078 | } |
| 1079 | |
| 1080 | #ifdef SMP |
| 1081 | |
| 1082 | static |
| 1083 | void |
| 1084 | need_user_resched_remote(void *dummy) |
| 1085 | { |
| 1086 | globaldata_t gd = mycpu; |
| 1087 | bsd4_pcpu_t dd = &bsd4_pcpu[gd->gd_cpuid]; |
| 1088 | |
| 1089 | need_user_resched(); |
| 1090 | lwkt_schedule(&dd->helper_thread); |
| 1091 | } |
| 1092 | |
| 1093 | #endif |
| 1094 | |
| 1095 | /* |
| 1096 | * bsd4_remrunqueue_locked() removes a given process from the run queue |
| 1097 | * that it is on, clearing the queue busy bit if it becomes empty. |
| 1098 | * |
| 1099 | * Note that user process scheduler is different from the LWKT schedule. |
| 1100 | * The user process scheduler only manages user processes but it uses LWKT |
| 1101 | * underneath, and a user process operating in the kernel will often be |
| 1102 | * 'released' from our management. |
| 1103 | * |
| 1104 | * MPSAFE - bsd4_spin must be held exclusively on call |
| 1105 | */ |
| 1106 | static void |
| 1107 | bsd4_remrunqueue_locked(struct lwp *lp) |
| 1108 | { |
| 1109 | struct rq *q; |
| 1110 | u_int32_t *which; |
| 1111 | u_int8_t pri; |
| 1112 | |
| 1113 | KKASSERT(lp->lwp_mpflags & LWP_MP_ONRUNQ); |
| 1114 | atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ); |
| 1115 | --bsd4_runqcount; |
| 1116 | KKASSERT(bsd4_runqcount >= 0); |
| 1117 | |
| 1118 | pri = lp->lwp_rqindex; |
| 1119 | switch(lp->lwp_rqtype) { |
| 1120 | case RTP_PRIO_NORMAL: |
| 1121 | q = &bsd4_queues[pri]; |
| 1122 | which = &bsd4_queuebits; |
| 1123 | break; |
| 1124 | case RTP_PRIO_REALTIME: |
| 1125 | case RTP_PRIO_FIFO: |
| 1126 | q = &bsd4_rtqueues[pri]; |
| 1127 | which = &bsd4_rtqueuebits; |
| 1128 | break; |
| 1129 | case RTP_PRIO_IDLE: |
| 1130 | q = &bsd4_idqueues[pri]; |
| 1131 | which = &bsd4_idqueuebits; |
| 1132 | break; |
| 1133 | default: |
| 1134 | panic("remrunqueue: invalid rtprio type"); |
| 1135 | /* NOT REACHED */ |
| 1136 | } |
| 1137 | TAILQ_REMOVE(q, lp, lwp_procq); |
| 1138 | if (TAILQ_EMPTY(q)) { |
| 1139 | KASSERT((*which & (1 << pri)) != 0, |
| 1140 | ("remrunqueue: remove from empty queue")); |
| 1141 | *which &= ~(1 << pri); |
| 1142 | } |
| 1143 | } |
| 1144 | |
| 1145 | /* |
| 1146 | * bsd4_setrunqueue_locked() |
| 1147 | * |
| 1148 | * Add a process whos rqtype and rqindex had previously been calculated |
| 1149 | * onto the appropriate run queue. Determine if the addition requires |
| 1150 | * a reschedule on a cpu and return the cpuid or -1. |
| 1151 | * |
| 1152 | * NOTE: Lower priorities are better priorities. |
| 1153 | * |
| 1154 | * MPSAFE - bsd4_spin must be held exclusively on call |
| 1155 | */ |
| 1156 | static void |
| 1157 | bsd4_setrunqueue_locked(struct lwp *lp) |
| 1158 | { |
| 1159 | struct rq *q; |
| 1160 | u_int32_t *which; |
| 1161 | int pri; |
| 1162 | |
| 1163 | KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0); |
| 1164 | atomic_set_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ); |
| 1165 | ++bsd4_runqcount; |
| 1166 | |
| 1167 | pri = lp->lwp_rqindex; |
| 1168 | |
| 1169 | switch(lp->lwp_rqtype) { |
| 1170 | case RTP_PRIO_NORMAL: |
| 1171 | q = &bsd4_queues[pri]; |
| 1172 | which = &bsd4_queuebits; |
| 1173 | break; |
| 1174 | case RTP_PRIO_REALTIME: |
| 1175 | case RTP_PRIO_FIFO: |
| 1176 | q = &bsd4_rtqueues[pri]; |
| 1177 | which = &bsd4_rtqueuebits; |
| 1178 | break; |
| 1179 | case RTP_PRIO_IDLE: |
| 1180 | q = &bsd4_idqueues[pri]; |
| 1181 | which = &bsd4_idqueuebits; |
| 1182 | break; |
| 1183 | default: |
| 1184 | panic("remrunqueue: invalid rtprio type"); |
| 1185 | /* NOT REACHED */ |
| 1186 | } |
| 1187 | |
| 1188 | /* |
| 1189 | * Add to the correct queue and set the appropriate bit. If no |
| 1190 | * lower priority (i.e. better) processes are in the queue then |
| 1191 | * we want a reschedule, calculate the best cpu for the job. |
| 1192 | * |
| 1193 | * Always run reschedules on the LWPs original cpu. |
| 1194 | */ |
| 1195 | TAILQ_INSERT_TAIL(q, lp, lwp_procq); |
| 1196 | *which |= 1 << pri; |
| 1197 | } |
| 1198 | |
| 1199 | #ifdef SMP |
| 1200 | |
| 1201 | /* |
| 1202 | * For SMP systems a user scheduler helper thread is created for each |
| 1203 | * cpu and is used to allow one cpu to wakeup another for the purposes of |
| 1204 | * scheduling userland threads from setrunqueue(). |
| 1205 | * |
| 1206 | * UP systems do not need the helper since there is only one cpu. |
| 1207 | * |
| 1208 | * We can't use the idle thread for this because we might block. |
| 1209 | * Additionally, doing things this way allows us to HLT idle cpus |
| 1210 | * on MP systems. |
| 1211 | * |
| 1212 | * MPSAFE |
| 1213 | */ |
| 1214 | static void |
| 1215 | sched_thread(void *dummy) |
| 1216 | { |
| 1217 | globaldata_t gd; |
| 1218 | bsd4_pcpu_t dd; |
| 1219 | bsd4_pcpu_t tmpdd; |
| 1220 | struct lwp *nlp; |
| 1221 | cpumask_t mask; |
| 1222 | int cpuid; |
| 1223 | #ifdef SMP |
| 1224 | cpumask_t tmpmask; |
| 1225 | int tmpid; |
| 1226 | #endif |
| 1227 | |
| 1228 | gd = mycpu; |
| 1229 | cpuid = gd->gd_cpuid; /* doesn't change */ |
| 1230 | mask = gd->gd_cpumask; /* doesn't change */ |
| 1231 | dd = &bsd4_pcpu[cpuid]; |
| 1232 | |
| 1233 | /* |
| 1234 | * Since we are woken up only when no user processes are scheduled |
| 1235 | * on a cpu, we can run at an ultra low priority. |
| 1236 | */ |
| 1237 | lwkt_setpri_self(TDPRI_USER_SCHEDULER); |
| 1238 | |
| 1239 | for (;;) { |
| 1240 | /* |
| 1241 | * We use the LWKT deschedule-interlock trick to avoid racing |
| 1242 | * bsd4_rdyprocmask. This means we cannot block through to the |
| 1243 | * manual lwkt_switch() call we make below. |
| 1244 | */ |
| 1245 | crit_enter_gd(gd); |
| 1246 | lwkt_deschedule_self(gd->gd_curthread); |
| 1247 | spin_lock(&bsd4_spin); |
| 1248 | atomic_set_cpumask(&bsd4_rdyprocmask, mask); |
| 1249 | |
| 1250 | clear_user_resched(); /* This satisfied the reschedule request */ |
| 1251 | dd->rrcount = 0; /* Reset the round-robin counter */ |
| 1252 | |
| 1253 | if ((bsd4_curprocmask & mask) == 0) { |
| 1254 | /* |
| 1255 | * No thread is currently scheduled. |
| 1256 | */ |
| 1257 | KKASSERT(dd->uschedcp == NULL); |
| 1258 | if ((nlp = chooseproc_locked(NULL)) != NULL) { |
| 1259 | atomic_set_cpumask(&bsd4_curprocmask, mask); |
| 1260 | dd->upri = nlp->lwp_priority; |
| 1261 | dd->uschedcp = nlp; |
| 1262 | spin_unlock(&bsd4_spin); |
| 1263 | #ifdef SMP |
| 1264 | lwkt_acquire(nlp->lwp_thread); |
| 1265 | #endif |
| 1266 | lwkt_schedule(nlp->lwp_thread); |
| 1267 | } else { |
| 1268 | spin_unlock(&bsd4_spin); |
| 1269 | } |
| 1270 | } else if (bsd4_runqcount) { |
| 1271 | if ((nlp = chooseproc_locked(dd->uschedcp)) != NULL) { |
| 1272 | dd->upri = nlp->lwp_priority; |
| 1273 | dd->uschedcp = nlp; |
| 1274 | spin_unlock(&bsd4_spin); |
| 1275 | #ifdef SMP |
| 1276 | lwkt_acquire(nlp->lwp_thread); |
| 1277 | #endif |
| 1278 | lwkt_schedule(nlp->lwp_thread); |
| 1279 | } else { |
| 1280 | /* |
| 1281 | * CHAINING CONDITION TRAIN |
| 1282 | * |
| 1283 | * We could not deal with the scheduler wakeup |
| 1284 | * request on this cpu, locate a ready scheduler |
| 1285 | * with no current lp assignment and chain to it. |
| 1286 | * |
| 1287 | * This ensures that a wakeup race which fails due |
| 1288 | * to priority test does not leave other unscheduled |
| 1289 | * cpus idle when the runqueue is not empty. |
| 1290 | */ |
| 1291 | tmpmask = ~bsd4_curprocmask & bsd4_rdyprocmask & |
| 1292 | smp_active_mask; |
| 1293 | if (tmpmask) { |
| 1294 | tmpid = BSFCPUMASK(tmpmask); |
| 1295 | tmpdd = &bsd4_pcpu[tmpid]; |
| 1296 | atomic_clear_cpumask(&bsd4_rdyprocmask, |
| 1297 | CPUMASK(tmpid)); |
| 1298 | spin_unlock(&bsd4_spin); |
| 1299 | lwkt_schedule(&tmpdd->helper_thread); |
| 1300 | } else { |
| 1301 | spin_unlock(&bsd4_spin); |
| 1302 | } |
| 1303 | } |
| 1304 | } else { |
| 1305 | /* |
| 1306 | * The runq is empty. |
| 1307 | */ |
| 1308 | spin_unlock(&bsd4_spin); |
| 1309 | } |
| 1310 | |
| 1311 | /* |
| 1312 | * We're descheduled unless someone scheduled us. Switch away. |
| 1313 | * Exiting the critical section will cause splz() to be called |
| 1314 | * for us if interrupts and such are pending. |
| 1315 | */ |
| 1316 | crit_exit_gd(gd); |
| 1317 | lwkt_switch(); |
| 1318 | } |
| 1319 | } |
| 1320 | |
| 1321 | /* |
| 1322 | * Setup our scheduler helpers. Note that curprocmask bit 0 has already |
| 1323 | * been cleared by rqinit() and we should not mess with it further. |
| 1324 | */ |
| 1325 | static void |
| 1326 | sched_thread_cpu_init(void) |
| 1327 | { |
| 1328 | int i; |
| 1329 | |
| 1330 | if (bootverbose) |
| 1331 | kprintf("start scheduler helpers on cpus:"); |
| 1332 | |
| 1333 | for (i = 0; i < ncpus; ++i) { |
| 1334 | bsd4_pcpu_t dd = &bsd4_pcpu[i]; |
| 1335 | cpumask_t mask = CPUMASK(i); |
| 1336 | |
| 1337 | if ((mask & smp_active_mask) == 0) |
| 1338 | continue; |
| 1339 | |
| 1340 | if (bootverbose) |
| 1341 | kprintf(" %d", i); |
| 1342 | |
| 1343 | lwkt_create(sched_thread, NULL, NULL, &dd->helper_thread, |
| 1344 | TDF_NOSTART, i, "usched %d", i); |
| 1345 | |
| 1346 | /* |
| 1347 | * Allow user scheduling on the target cpu. cpu #0 has already |
| 1348 | * been enabled in rqinit(). |
| 1349 | */ |
| 1350 | if (i) |
| 1351 | atomic_clear_cpumask(&bsd4_curprocmask, mask); |
| 1352 | atomic_set_cpumask(&bsd4_rdyprocmask, mask); |
| 1353 | dd->upri = PRIBASE_NULL; |
| 1354 | } |
| 1355 | if (bootverbose) |
| 1356 | kprintf("\n"); |
| 1357 | } |
| 1358 | SYSINIT(uschedtd, SI_BOOT2_USCHED, SI_ORDER_SECOND, |
| 1359 | sched_thread_cpu_init, NULL) |
| 1360 | |
| 1361 | #endif |
| 1362 | |