FreeBSD/Linux Kernel Cross Reference
sys/kern/sched_ule.c
1 /*-
2 * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@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 unmodified, this list of conditions, and the following
10 * disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 /*
28 * This file implements the ULE scheduler. ULE supports independent CPU
29 * run queues and fine grain locking. It has superior interactive
30 * performance under load even on uni-processor systems.
31 *
32 * etymology:
33 * ULE is the last three letters in schedule. It owes its name to a
34 * generic user created for a scheduling system by Paul Mikesell at
35 * Isilon Systems and a general lack of creativity on the part of the author.
36 */
37
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD: releng/7.2/sys/kern/sched_ule.c 204409 2010-02-27 10:55:43Z cperciva $");
40
41 #include "opt_hwpmc_hooks.h"
42 #include "opt_kdtrace.h"
43 #include "opt_sched.h"
44
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/kdb.h>
48 #include <sys/kernel.h>
49 #include <sys/ktr.h>
50 #include <sys/lock.h>
51 #include <sys/mutex.h>
52 #include <sys/proc.h>
53 #include <sys/resource.h>
54 #include <sys/resourcevar.h>
55 #include <sys/sched.h>
56 #include <sys/smp.h>
57 #include <sys/sx.h>
58 #include <sys/sysctl.h>
59 #include <sys/sysproto.h>
60 #include <sys/turnstile.h>
61 #include <sys/umtx.h>
62 #include <sys/vmmeter.h>
63 #include <sys/cpuset.h>
64 #ifdef KTRACE
65 #include <sys/uio.h>
66 #include <sys/ktrace.h>
67 #endif
68
69 #ifdef HWPMC_HOOKS
70 #include <sys/pmckern.h>
71 #endif
72
73 #ifdef KDTRACE_HOOKS
74 #include <sys/dtrace_bsd.h>
75 int dtrace_vtime_active;
76 dtrace_vtime_switch_func_t dtrace_vtime_switch_func;
77 #endif
78
79 #include <machine/cpu.h>
80 #include <machine/smp.h>
81
82 #if !defined(__i386__) && !defined(__amd64__) && !defined(__arm__)
83 #error "This architecture is not currently compatible with ULE"
84 #endif
85
86 #define KTR_ULE 0
87
88 /*
89 * Thread scheduler specific section. All fields are protected
90 * by the thread lock.
91 */
92 struct td_sched {
93 TAILQ_ENTRY(td_sched) ts_procq; /* Run queue. */
94 struct thread *ts_thread; /* Active associated thread. */
95 struct runq *ts_runq; /* Run-queue we're queued on. */
96 short ts_flags; /* TSF_* flags. */
97 u_char ts_rqindex; /* Run queue index. */
98 u_char ts_cpu; /* CPU that we have affinity for. */
99 int ts_slice; /* Ticks of slice remaining. */
100 u_int ts_slptime; /* Number of ticks we vol. slept */
101 u_int ts_runtime; /* Number of ticks we were running */
102 /* The following variables are only used for pctcpu calculation */
103 int ts_ltick; /* Last tick that we were running on */
104 int ts_ftick; /* First tick that we were running on */
105 int ts_ticks; /* Tick count */
106 #ifdef SMP
107 int ts_rltick; /* Real last tick, for affinity. */
108 #endif
109 };
110 /* flags kept in ts_flags */
111 #define TSF_BOUND 0x0001 /* Thread can not migrate. */
112 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */
113
114 static struct td_sched td_sched0;
115
116 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0)
117 #define THREAD_CAN_SCHED(td, cpu) \
118 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask)
119
120 /*
121 * Cpu percentage computation macros and defines.
122 *
123 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across.
124 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across.
125 * SCHED_TICK_MAX: Maximum number of ticks before scaling back.
126 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results.
127 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count.
128 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks.
129 */
130 #define SCHED_TICK_SECS 10
131 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS)
132 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz)
133 #define SCHED_TICK_SHIFT 10
134 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT)
135 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz))
136
137 /*
138 * These macros determine priorities for non-interactive threads. They are
139 * assigned a priority based on their recent cpu utilization as expressed
140 * by the ratio of ticks to the tick total. NHALF priorities at the start
141 * and end of the MIN to MAX timeshare range are only reachable with negative
142 * or positive nice respectively.
143 *
144 * PRI_RANGE: Priority range for utilization dependent priorities.
145 * PRI_NRESV: Number of nice values.
146 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total.
147 * PRI_NICE: Determines the part of the priority inherited from nice.
148 */
149 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN)
150 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2)
151 #define SCHED_PRI_MIN (PRI_MIN_TIMESHARE + SCHED_PRI_NHALF)
152 #define SCHED_PRI_MAX (PRI_MAX_TIMESHARE - SCHED_PRI_NHALF)
153 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN)
154 #define SCHED_PRI_TICKS(ts) \
155 (SCHED_TICK_HZ((ts)) / \
156 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE))
157 #define SCHED_PRI_NICE(nice) (nice)
158
159 /*
160 * These determine the interactivity of a process. Interactivity differs from
161 * cpu utilization in that it expresses the voluntary time slept vs time ran
162 * while cpu utilization includes all time not running. This more accurately
163 * models the intent of the thread.
164 *
165 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate
166 * before throttling back.
167 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time.
168 * INTERACT_MAX: Maximum interactivity value. Smaller is better.
169 * INTERACT_THRESH: Threshhold for placement on the current runq.
170 */
171 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT)
172 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT)
173 #define SCHED_INTERACT_MAX (100)
174 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2)
175 #define SCHED_INTERACT_THRESH (30)
176
177 /*
178 * tickincr: Converts a stathz tick into a hz domain scaled by
179 * the shift factor. Without the shift the error rate
180 * due to rounding would be unacceptably high.
181 * realstathz: stathz is sometimes 0 and run off of hz.
182 * sched_slice: Runtime of each thread before rescheduling.
183 * preempt_thresh: Priority threshold for preemption and remote IPIs.
184 */
185 static int sched_interact = SCHED_INTERACT_THRESH;
186 static int realstathz;
187 static int tickincr;
188 static int sched_slice;
189 #ifdef PREEMPTION
190 #ifdef FULL_PREEMPTION
191 static int preempt_thresh = PRI_MAX_IDLE;
192 #else
193 static int preempt_thresh = PRI_MIN_KERN;
194 #endif
195 #else
196 static int preempt_thresh = 0;
197 #endif
198
199 /*
200 * tdq - per processor runqs and statistics. All fields are protected by the
201 * tdq_lock. The load and lowpri may be accessed without to avoid excess
202 * locking in sched_pickcpu();
203 */
204 struct tdq {
205 struct mtx *tdq_lock; /* Pointer to group lock. */
206 struct runq tdq_realtime; /* real-time run queue. */
207 struct runq tdq_timeshare; /* timeshare run queue. */
208 struct runq tdq_idle; /* Queue of IDLE threads. */
209 int tdq_load; /* Aggregate load. */
210 u_char tdq_idx; /* Current insert index. */
211 u_char tdq_ridx; /* Current removal index. */
212 #ifdef SMP
213 u_char tdq_lowpri; /* Lowest priority thread. */
214 int tdq_transferable; /* Transferable thread count. */
215 LIST_ENTRY(tdq) tdq_siblings; /* Next in tdq group. */
216 struct tdq_group *tdq_group; /* Our processor group. */
217 #else
218 int tdq_sysload; /* For loadavg, !ITHD load. */
219 #endif
220 } __aligned(64);
221
222
223 #ifdef SMP
224 /*
225 * tdq groups are groups of processors which can cheaply share threads. When
226 * one processor in the group goes idle it will check the runqs of the other
227 * processors in its group prior to halting and waiting for an interrupt.
228 * These groups are suitable for SMT (Symetric Multi-Threading) and not NUMA.
229 * In a numa environment we'd want an idle bitmap per group and a two tiered
230 * load balancer.
231 */
232 struct tdq_group {
233 struct mtx tdg_lock; /* Protects all fields below. */
234 int tdg_cpus; /* Count of CPUs in this tdq group. */
235 cpumask_t tdg_cpumask; /* Mask of cpus in this group. */
236 cpumask_t tdg_idlemask; /* Idle cpus in this group. */
237 cpumask_t tdg_mask; /* Bit mask for first cpu. */
238 int tdg_load; /* Total load of this group. */
239 int tdg_transferable; /* Transferable load of this group. */
240 LIST_HEAD(, tdq) tdg_members; /* Linked list of all members. */
241 char tdg_name[16]; /* lock name. */
242 } __aligned(64);
243
244 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 300))
245 #define SCHED_AFFINITY(ts) ((ts)->ts_rltick > ticks - affinity)
246
247 /*
248 * Run-time tunables.
249 */
250 static int rebalance = 1;
251 static int balance_interval = 128; /* Default set in sched_initticks(). */
252 static int pick_pri = 1;
253 static int affinity;
254 static int tryself = 1;
255 static int steal_htt = 1;
256 static int steal_idle = 1;
257 static int steal_thresh = 2;
258 static int topology = 0;
259
260 /*
261 * One thread queue per processor.
262 */
263 static volatile cpumask_t tdq_idle;
264 static int tdg_maxid;
265 static struct tdq tdq_cpu[MAXCPU];
266 static struct tdq_group tdq_groups[MAXCPU];
267 static struct tdq *balance_tdq;
268 static int balance_group_ticks;
269 static int balance_ticks;
270
271 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)])
272 #define TDQ_CPU(x) (&tdq_cpu[(x)])
273 #define TDQ_ID(x) ((int)((x) - tdq_cpu))
274 #define TDQ_GROUP(x) (&tdq_groups[(x)])
275 #define TDG_ID(x) ((int)((x) - tdq_groups))
276 #else /* !SMP */
277 static struct tdq tdq_cpu;
278 static struct mtx tdq_lock;
279
280 #define TDQ_ID(x) (0)
281 #define TDQ_SELF() (&tdq_cpu)
282 #define TDQ_CPU(x) (&tdq_cpu)
283 #endif
284
285 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type))
286 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t)))
287 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f))
288 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t)))
289 #define TDQ_LOCKPTR(t) ((t)->tdq_lock)
290
291 static void sched_priority(struct thread *);
292 static void sched_thread_priority(struct thread *, u_char);
293 static int sched_interact_score(struct thread *);
294 static void sched_interact_update(struct thread *);
295 static void sched_interact_fork(struct thread *);
296 static void sched_pctcpu_update(struct td_sched *);
297
298 /* Operations on per processor queues */
299 static struct td_sched * tdq_choose(struct tdq *);
300 static void tdq_setup(struct tdq *);
301 static void tdq_load_add(struct tdq *, struct td_sched *);
302 static void tdq_load_rem(struct tdq *, struct td_sched *);
303 static __inline void tdq_runq_add(struct tdq *, struct td_sched *, int);
304 static __inline void tdq_runq_rem(struct tdq *, struct td_sched *);
305 void tdq_print(int cpu);
306 static void runq_print(struct runq *rq);
307 static void tdq_add(struct tdq *, struct thread *, int);
308 #ifdef SMP
309 static void tdq_move(struct tdq *, struct tdq *);
310 static int tdq_idled(struct tdq *);
311 static void tdq_notify(struct td_sched *);
312 static struct td_sched *tdq_steal(struct tdq *, int);
313 static struct td_sched *runq_steal(struct runq *, int);
314 static int sched_pickcpu(struct thread *, int);
315 static void sched_balance(void);
316 static void sched_balance_groups(void);
317 static void sched_balance_group(struct tdq_group *);
318 static void sched_balance_pair(struct tdq *, struct tdq *);
319 static inline struct tdq *sched_setcpu(struct td_sched *, int, int);
320 static inline struct mtx *thread_block_switch(struct thread *);
321 static inline void thread_unblock_switch(struct thread *, struct mtx *);
322 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int);
323 #endif
324
325 static void sched_setup(void *dummy);
326 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL);
327
328 static void sched_initticks(void *dummy);
329 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks,
330 NULL);
331
332 /*
333 * Print the threads waiting on a run-queue.
334 */
335 static void
336 runq_print(struct runq *rq)
337 {
338 struct rqhead *rqh;
339 struct td_sched *ts;
340 int pri;
341 int j;
342 int i;
343
344 for (i = 0; i < RQB_LEN; i++) {
345 printf("\t\trunq bits %d 0x%zx\n",
346 i, rq->rq_status.rqb_bits[i]);
347 for (j = 0; j < RQB_BPW; j++)
348 if (rq->rq_status.rqb_bits[i] & (1ul << j)) {
349 pri = j + (i << RQB_L2BPW);
350 rqh = &rq->rq_queues[pri];
351 TAILQ_FOREACH(ts, rqh, ts_procq) {
352 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n",
353 ts->ts_thread, ts->ts_thread->td_proc->p_comm, ts->ts_thread->td_priority, ts->ts_rqindex, pri);
354 }
355 }
356 }
357 }
358
359 /*
360 * Print the status of a per-cpu thread queue. Should be a ddb show cmd.
361 */
362 void
363 tdq_print(int cpu)
364 {
365 struct tdq *tdq;
366
367 tdq = TDQ_CPU(cpu);
368
369 printf("tdq %d:\n", TDQ_ID(tdq));
370 printf("\tlockptr %p\n", TDQ_LOCKPTR(tdq));
371 printf("\tload: %d\n", tdq->tdq_load);
372 printf("\ttimeshare idx: %d\n", tdq->tdq_idx);
373 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx);
374 printf("\trealtime runq:\n");
375 runq_print(&tdq->tdq_realtime);
376 printf("\ttimeshare runq:\n");
377 runq_print(&tdq->tdq_timeshare);
378 printf("\tidle runq:\n");
379 runq_print(&tdq->tdq_idle);
380 #ifdef SMP
381 printf("\tload transferable: %d\n", tdq->tdq_transferable);
382 printf("\tlowest priority: %d\n", tdq->tdq_lowpri);
383 printf("\tgroup: %d\n", TDG_ID(tdq->tdq_group));
384 printf("\tLock name: %s\n", tdq->tdq_group->tdg_name);
385 #endif
386 }
387
388 #define TS_RQ_PPQ (((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) + 1) / RQ_NQS)
389 /*
390 * Add a thread to the actual run-queue. Keeps transferable counts up to
391 * date with what is actually on the run-queue. Selects the correct
392 * queue position for timeshare threads.
393 */
394 static __inline void
395 tdq_runq_add(struct tdq *tdq, struct td_sched *ts, int flags)
396 {
397 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
398 THREAD_LOCK_ASSERT(ts->ts_thread, MA_OWNED);
399 #ifdef SMP
400 if (THREAD_CAN_MIGRATE(ts->ts_thread)) {
401 tdq->tdq_transferable++;
402 tdq->tdq_group->tdg_transferable++;
403 ts->ts_flags |= TSF_XFERABLE;
404 }
405 #endif
406 if (ts->ts_runq == &tdq->tdq_timeshare) {
407 u_char pri;
408
409 pri = ts->ts_thread->td_priority;
410 KASSERT(pri <= PRI_MAX_TIMESHARE && pri >= PRI_MIN_TIMESHARE,
411 ("Invalid priority %d on timeshare runq", pri));
412 /*
413 * This queue contains only priorities between MIN and MAX
414 * realtime. Use the whole queue to represent these values.
415 */
416 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) {
417 pri = (pri - PRI_MIN_TIMESHARE) / TS_RQ_PPQ;
418 pri = (pri + tdq->tdq_idx) % RQ_NQS;
419 /*
420 * This effectively shortens the queue by one so we
421 * can have a one slot difference between idx and
422 * ridx while we wait for threads to drain.
423 */
424 if (tdq->tdq_ridx != tdq->tdq_idx &&
425 pri == tdq->tdq_ridx)
426 pri = (unsigned char)(pri - 1) % RQ_NQS;
427 } else
428 pri = tdq->tdq_ridx;
429 runq_add_pri(ts->ts_runq, ts, pri, flags);
430 } else
431 runq_add(ts->ts_runq, ts, flags);
432 }
433
434 /*
435 * Remove a thread from a run-queue. This typically happens when a thread
436 * is selected to run. Running threads are not on the queue and the
437 * transferable count does not reflect them.
438 */
439 static __inline void
440 tdq_runq_rem(struct tdq *tdq, struct td_sched *ts)
441 {
442 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
443 KASSERT(ts->ts_runq != NULL,
444 ("tdq_runq_remove: thread %p null ts_runq", ts->ts_thread));
445 #ifdef SMP
446 if (ts->ts_flags & TSF_XFERABLE) {
447 tdq->tdq_transferable--;
448 tdq->tdq_group->tdg_transferable--;
449 ts->ts_flags &= ~TSF_XFERABLE;
450 }
451 #endif
452 if (ts->ts_runq == &tdq->tdq_timeshare) {
453 if (tdq->tdq_idx != tdq->tdq_ridx)
454 runq_remove_idx(ts->ts_runq, ts, &tdq->tdq_ridx);
455 else
456 runq_remove_idx(ts->ts_runq, ts, NULL);
457 /*
458 * For timeshare threads we update the priority here so
459 * the priority reflects the time we've been sleeping.
460 */
461 ts->ts_ltick = ticks;
462 sched_pctcpu_update(ts);
463 sched_priority(ts->ts_thread);
464 } else
465 runq_remove(ts->ts_runq, ts);
466 }
467
468 /*
469 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load
470 * for this thread to the referenced thread queue.
471 */
472 static void
473 tdq_load_add(struct tdq *tdq, struct td_sched *ts)
474 {
475 int class;
476
477 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
478 THREAD_LOCK_ASSERT(ts->ts_thread, MA_OWNED);
479 class = PRI_BASE(ts->ts_thread->td_pri_class);
480 tdq->tdq_load++;
481 CTR2(KTR_SCHED, "cpu %d load: %d", TDQ_ID(tdq), tdq->tdq_load);
482 if (class != PRI_ITHD &&
483 (ts->ts_thread->td_proc->p_flag & P_NOLOAD) == 0)
484 #ifdef SMP
485 tdq->tdq_group->tdg_load++;
486 #else
487 tdq->tdq_sysload++;
488 #endif
489 }
490
491 /*
492 * Remove the load from a thread that is transitioning to a sleep state or
493 * exiting.
494 */
495 static void
496 tdq_load_rem(struct tdq *tdq, struct td_sched *ts)
497 {
498 int class;
499
500 THREAD_LOCK_ASSERT(ts->ts_thread, MA_OWNED);
501 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
502 class = PRI_BASE(ts->ts_thread->td_pri_class);
503 if (class != PRI_ITHD &&
504 (ts->ts_thread->td_proc->p_flag & P_NOLOAD) == 0)
505 #ifdef SMP
506 tdq->tdq_group->tdg_load--;
507 #else
508 tdq->tdq_sysload--;
509 #endif
510 KASSERT(tdq->tdq_load != 0,
511 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq)));
512 tdq->tdq_load--;
513 CTR1(KTR_SCHED, "load: %d", tdq->tdq_load);
514 ts->ts_runq = NULL;
515 }
516
517 #ifdef SMP
518 /*
519 * sched_balance is a simple CPU load balancing algorithm. It operates by
520 * finding the least loaded and most loaded cpu and equalizing their load
521 * by migrating some processes.
522 *
523 * Dealing only with two CPUs at a time has two advantages. Firstly, most
524 * installations will only have 2 cpus. Secondly, load balancing too much at
525 * once can have an unpleasant effect on the system. The scheduler rarely has
526 * enough information to make perfect decisions. So this algorithm chooses
527 * simplicity and more gradual effects on load in larger systems.
528 *
529 */
530 static void
531 sched_balance()
532 {
533 struct tdq_group *high;
534 struct tdq_group *low;
535 struct tdq_group *tdg;
536 struct tdq *tdq;
537 int cnt;
538 int i;
539
540 /*
541 * Select a random time between .5 * balance_interval and
542 * 1.5 * balance_interval.
543 */
544 balance_ticks = max(balance_interval / 2, 1);
545 balance_ticks += random() % balance_interval;
546 if (smp_started == 0 || rebalance == 0)
547 return;
548 tdq = TDQ_SELF();
549 TDQ_UNLOCK(tdq);
550 low = high = NULL;
551 i = random() % (tdg_maxid + 1);
552 for (cnt = 0; cnt <= tdg_maxid; cnt++) {
553 tdg = TDQ_GROUP(i);
554 /*
555 * Find the CPU with the highest load that has some
556 * threads to transfer.
557 */
558 if ((high == NULL || tdg->tdg_load > high->tdg_load)
559 && tdg->tdg_transferable)
560 high = tdg;
561 if (low == NULL || tdg->tdg_load < low->tdg_load)
562 low = tdg;
563 if (++i > tdg_maxid)
564 i = 0;
565 }
566 if (low != NULL && high != NULL && high != low)
567 sched_balance_pair(LIST_FIRST(&high->tdg_members),
568 LIST_FIRST(&low->tdg_members));
569 TDQ_LOCK(tdq);
570 }
571
572 /*
573 * Balance load between CPUs in a group. Will only migrate within the group.
574 */
575 static void
576 sched_balance_groups()
577 {
578 struct tdq *tdq;
579 int i;
580
581 /*
582 * Select a random time between .5 * balance_interval and
583 * 1.5 * balance_interval.
584 */
585 balance_group_ticks = max(balance_interval / 2, 1);
586 balance_group_ticks += random() % balance_interval;
587 if (smp_started == 0 || rebalance == 0)
588 return;
589 tdq = TDQ_SELF();
590 TDQ_UNLOCK(tdq);
591 for (i = 0; i <= tdg_maxid; i++)
592 sched_balance_group(TDQ_GROUP(i));
593 TDQ_LOCK(tdq);
594 }
595
596 /*
597 * Finds the greatest imbalance between two tdqs in a group.
598 */
599 static void
600 sched_balance_group(struct tdq_group *tdg)
601 {
602 struct tdq *tdq;
603 struct tdq *high;
604 struct tdq *low;
605 int load;
606
607 if (tdg->tdg_transferable == 0)
608 return;
609 low = NULL;
610 high = NULL;
611 LIST_FOREACH(tdq, &tdg->tdg_members, tdq_siblings) {
612 load = tdq->tdq_load;
613 if (high == NULL || load > high->tdq_load)
614 high = tdq;
615 if (low == NULL || load < low->tdq_load)
616 low = tdq;
617 }
618 if (high != NULL && low != NULL && high != low)
619 sched_balance_pair(high, low);
620 }
621
622 /*
623 * Lock two thread queues using their address to maintain lock order.
624 */
625 static void
626 tdq_lock_pair(struct tdq *one, struct tdq *two)
627 {
628 if (one < two) {
629 TDQ_LOCK(one);
630 TDQ_LOCK_FLAGS(two, MTX_DUPOK);
631 } else {
632 TDQ_LOCK(two);
633 TDQ_LOCK_FLAGS(one, MTX_DUPOK);
634 }
635 }
636
637 /*
638 * Unlock two thread queues. Order is not important here.
639 */
640 static void
641 tdq_unlock_pair(struct tdq *one, struct tdq *two)
642 {
643 TDQ_UNLOCK(one);
644 TDQ_UNLOCK(two);
645 }
646
647 /*
648 * Transfer load between two imbalanced thread queues.
649 */
650 static void
651 sched_balance_pair(struct tdq *high, struct tdq *low)
652 {
653 int transferable;
654 int high_load;
655 int low_load;
656 int move;
657 int diff;
658 int i;
659
660 tdq_lock_pair(high, low);
661 /*
662 * If we're transfering within a group we have to use this specific
663 * tdq's transferable count, otherwise we can steal from other members
664 * of the group.
665 */
666 if (high->tdq_group == low->tdq_group) {
667 transferable = high->tdq_transferable;
668 high_load = high->tdq_load;
669 low_load = low->tdq_load;
670 } else {
671 transferable = high->tdq_group->tdg_transferable;
672 high_load = high->tdq_group->tdg_load;
673 low_load = low->tdq_group->tdg_load;
674 }
675 /*
676 * Determine what the imbalance is and then adjust that to how many
677 * threads we actually have to give up (transferable).
678 */
679 if (transferable != 0) {
680 diff = high_load - low_load;
681 move = diff / 2;
682 if (diff & 0x1)
683 move++;
684 move = min(move, transferable);
685 for (i = 0; i < move; i++)
686 tdq_move(high, low);
687 /*
688 * IPI the target cpu to force it to reschedule with the new
689 * workload.
690 */
691 ipi_selected(1 << TDQ_ID(low), IPI_PREEMPT);
692 }
693 tdq_unlock_pair(high, low);
694 return;
695 }
696
697 /*
698 * Move a thread from one thread queue to another.
699 */
700 static void
701 tdq_move(struct tdq *from, struct tdq *to)
702 {
703 struct td_sched *ts;
704 struct thread *td;
705 struct tdq *tdq;
706 int cpu;
707
708 TDQ_LOCK_ASSERT(from, MA_OWNED);
709 TDQ_LOCK_ASSERT(to, MA_OWNED);
710
711 tdq = from;
712 cpu = TDQ_ID(to);
713 ts = tdq_steal(tdq, cpu);
714 if (ts == NULL) {
715 struct tdq_group *tdg;
716
717 tdg = tdq->tdq_group;
718 LIST_FOREACH(tdq, &tdg->tdg_members, tdq_siblings) {
719 if (tdq == from || tdq->tdq_transferable == 0)
720 continue;
721 ts = tdq_steal(tdq, cpu);
722 break;
723 }
724 if (ts == NULL)
725 return;
726 }
727 if (tdq == to)
728 return;
729 td = ts->ts_thread;
730 /*
731 * Although the run queue is locked the thread may be blocked. Lock
732 * it to clear this and acquire the run-queue lock.
733 */
734 thread_lock(td);
735 /* Drop recursive lock on from acquired via thread_lock(). */
736 TDQ_UNLOCK(from);
737 sched_rem(td);
738 ts->ts_cpu = cpu;
739 td->td_lock = TDQ_LOCKPTR(to);
740 tdq_add(to, td, SRQ_YIELDING);
741 }
742
743 /*
744 * This tdq has idled. Try to steal a thread from another cpu and switch
745 * to it.
746 */
747 static int
748 tdq_idled(struct tdq *tdq)
749 {
750 struct tdq_group *tdg;
751 struct tdq *steal;
752 int highload;
753 int highcpu;
754 int cpu;
755
756 if (smp_started == 0 || steal_idle == 0)
757 return (1);
758 /* We don't want to be preempted while we're iterating over tdqs */
759 spinlock_enter();
760 tdg = tdq->tdq_group;
761 /*
762 * If we're in a cpu group, try and steal threads from another cpu in
763 * the group before idling. In a HTT group all cpus share the same
764 * run-queue lock, however, we still need a recursive lock to
765 * call tdq_move().
766 */
767 if (steal_htt && tdg->tdg_cpus > 1 && tdg->tdg_transferable) {
768 TDQ_LOCK(tdq);
769 LIST_FOREACH(steal, &tdg->tdg_members, tdq_siblings) {
770 if (steal == tdq || steal->tdq_transferable == 0)
771 continue;
772 TDQ_LOCK(steal);
773 goto steal;
774 }
775 TDQ_UNLOCK(tdq);
776 }
777 /*
778 * Find the least loaded CPU with a transferable thread and attempt
779 * to steal it. We make a lockless pass and then verify that the
780 * thread is still available after locking.
781 */
782 for (;;) {
783 highcpu = 0;
784 highload = 0;
785 for (cpu = 0; cpu <= mp_maxid; cpu++) {
786 if (CPU_ABSENT(cpu))
787 continue;
788 steal = TDQ_CPU(cpu);
789 if (steal->tdq_transferable == 0)
790 continue;
791 if (steal->tdq_load < highload)
792 continue;
793 highload = steal->tdq_load;
794 highcpu = cpu;
795 }
796 if (highload < steal_thresh)
797 break;
798 steal = TDQ_CPU(highcpu);
799 if (steal == tdq)
800 break;
801 tdq_lock_pair(tdq, steal);
802 if (steal->tdq_load >= steal_thresh && steal->tdq_transferable)
803 goto steal;
804 tdq_unlock_pair(tdq, steal);
805 }
806 spinlock_exit();
807 return (1);
808 steal:
809 spinlock_exit();
810 tdq_move(steal, tdq);
811 TDQ_UNLOCK(steal);
812 mi_switch(SW_VOL, NULL);
813 thread_unlock(curthread);
814
815 return (0);
816 }
817
818 /*
819 * Notify a remote cpu of new work. Sends an IPI if criteria are met.
820 */
821 static void
822 tdq_notify(struct td_sched *ts)
823 {
824 struct thread *ctd;
825 struct pcpu *pcpu;
826 int cpri;
827 int pri;
828 int cpu;
829
830 cpu = ts->ts_cpu;
831 pri = ts->ts_thread->td_priority;
832 pcpu = pcpu_find(cpu);
833 ctd = pcpu->pc_curthread;
834 cpri = ctd->td_priority;
835
836 /*
837 * If our priority is not better than the current priority there is
838 * nothing to do.
839 */
840 if (pri > cpri)
841 return;
842 /*
843 * Always IPI idle.
844 */
845 if (cpri > PRI_MIN_IDLE)
846 goto sendipi;
847 /*
848 * If we're realtime or better and there is timeshare or worse running
849 * send an IPI.
850 */
851 if (pri < PRI_MAX_REALTIME && cpri > PRI_MAX_REALTIME)
852 goto sendipi;
853 /*
854 * Otherwise only IPI if we exceed the threshold.
855 */
856 if (pri > preempt_thresh)
857 return;
858 sendipi:
859 ipi_selected(1 << cpu, IPI_PREEMPT);
860 }
861
862 /*
863 * Steals load from a timeshare queue. Honors the rotating queue head
864 * index.
865 */
866 static struct td_sched *
867 runq_steal_from(struct runq *rq, int cpu, u_char start)
868 {
869 struct td_sched *ts;
870 struct rqbits *rqb;
871 struct rqhead *rqh;
872 int first;
873 int bit;
874 int pri;
875 int i;
876
877 rqb = &rq->rq_status;
878 bit = start & (RQB_BPW -1);
879 pri = 0;
880 first = 0;
881 again:
882 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) {
883 if (rqb->rqb_bits[i] == 0)
884 continue;
885 if (bit != 0) {
886 for (pri = bit; pri < RQB_BPW; pri++)
887 if (rqb->rqb_bits[i] & (1ul << pri))
888 break;
889 if (pri >= RQB_BPW)
890 continue;
891 } else
892 pri = RQB_FFS(rqb->rqb_bits[i]);
893 pri += (i << RQB_L2BPW);
894 rqh = &rq->rq_queues[pri];
895 TAILQ_FOREACH(ts, rqh, ts_procq) {
896 if (first && THREAD_CAN_MIGRATE(ts->ts_thread) &&
897 THREAD_CAN_SCHED(ts->ts_thread, cpu))
898 return (ts);
899 first = 1;
900 }
901 }
902 if (start != 0) {
903 start = 0;
904 goto again;
905 }
906
907 return (NULL);
908 }
909
910 /*
911 * Steals load from a standard linear queue.
912 */
913 static struct td_sched *
914 runq_steal(struct runq *rq, int cpu)
915 {
916 struct rqhead *rqh;
917 struct rqbits *rqb;
918 struct td_sched *ts;
919 int word;
920 int bit;
921
922 rqb = &rq->rq_status;
923 for (word = 0; word < RQB_LEN; word++) {
924 if (rqb->rqb_bits[word] == 0)
925 continue;
926 for (bit = 0; bit < RQB_BPW; bit++) {
927 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0)
928 continue;
929 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)];
930 TAILQ_FOREACH(ts, rqh, ts_procq)
931 if (THREAD_CAN_MIGRATE(ts->ts_thread) &&
932 THREAD_CAN_SCHED(ts->ts_thread, cpu))
933 return (ts);
934 }
935 }
936 return (NULL);
937 }
938
939 /*
940 * Attempt to steal a thread in priority order from a thread queue.
941 */
942 static struct td_sched *
943 tdq_steal(struct tdq *tdq, int cpu)
944 {
945 struct td_sched *ts;
946
947 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
948 if ((ts = runq_steal(&tdq->tdq_realtime, cpu)) != NULL)
949 return (ts);
950 if ((ts = runq_steal_from(&tdq->tdq_timeshare,
951 cpu, tdq->tdq_ridx)) != NULL)
952 return (ts);
953 return (runq_steal(&tdq->tdq_idle, cpu));
954 }
955
956 /*
957 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the
958 * current lock and returns with the assigned queue locked.
959 */
960 static inline struct tdq *
961 sched_setcpu(struct td_sched *ts, int cpu, int flags)
962 {
963 struct thread *td;
964 struct tdq *tdq;
965
966 THREAD_LOCK_ASSERT(ts->ts_thread, MA_OWNED);
967
968 tdq = TDQ_CPU(cpu);
969 td = ts->ts_thread;
970 ts->ts_cpu = cpu;
971
972 /* If the lock matches just return the queue. */
973 if (td->td_lock == TDQ_LOCKPTR(tdq))
974 return (tdq);
975 #ifdef notyet
976 /*
977 * If the thread isn't running its lockptr is a
978 * turnstile or a sleepqueue. We can just lock_set without
979 * blocking.
980 */
981 if (TD_CAN_RUN(td)) {
982 TDQ_LOCK(tdq);
983 thread_lock_set(td, TDQ_LOCKPTR(tdq));
984 return (tdq);
985 }
986 #endif
987 /*
988 * The hard case, migration, we need to block the thread first to
989 * prevent order reversals with other cpus locks.
990 */
991 thread_lock_block(td);
992 TDQ_LOCK(tdq);
993 thread_lock_unblock(td, TDQ_LOCKPTR(tdq));
994 return (tdq);
995 }
996
997 /*
998 * Find the thread queue running the lowest priority thread.
999 */
1000 static int
1001 tdq_lowestpri(struct thread *td)
1002 {
1003 struct tdq *tdq;
1004 int lowpri;
1005 int lowcpu;
1006 int lowload;
1007 int load;
1008 int cpu;
1009 int pri;
1010
1011 lowload = 0;
1012 lowpri = lowcpu = 0;
1013 for (cpu = 0; cpu <= mp_maxid; cpu++) {
1014 if (CPU_ABSENT(cpu))
1015 continue;
1016 if (!THREAD_CAN_SCHED(td, cpu))
1017 continue;
1018 tdq = TDQ_CPU(cpu);
1019 pri = tdq->tdq_lowpri;
1020 load = TDQ_CPU(cpu)->tdq_load;
1021 CTR4(KTR_ULE,
1022 "cpu %d pri %d lowcpu %d lowpri %d",
1023 cpu, pri, lowcpu, lowpri);
1024 if (pri < lowpri)
1025 continue;
1026 if (lowpri && lowpri == pri && load > lowload)
1027 continue;
1028 lowpri = pri;
1029 lowcpu = cpu;
1030 lowload = load;
1031 }
1032
1033 return (lowcpu);
1034 }
1035
1036 /*
1037 * Find the thread queue with the least load.
1038 */
1039 static int
1040 tdq_lowestload(struct thread *td)
1041 {
1042 struct tdq *tdq;
1043 int lowload;
1044 int lowpri;
1045 int lowcpu;
1046 int load;
1047 int cpu;
1048 int pri;
1049
1050 lowcpu = 0;
1051 lowload = TDQ_CPU(0)->tdq_load;
1052 lowpri = TDQ_CPU(0)->tdq_lowpri;
1053 for (cpu = 1; cpu <= mp_maxid; cpu++) {
1054 if (CPU_ABSENT(cpu))
1055 continue;
1056 if (!THREAD_CAN_SCHED(td, cpu))
1057 continue;
1058 tdq = TDQ_CPU(cpu);
1059 load = tdq->tdq_load;
1060 pri = tdq->tdq_lowpri;
1061 CTR4(KTR_ULE, "cpu %d load %d lowcpu %d lowload %d",
1062 cpu, load, lowcpu, lowload);
1063 if (load > lowload)
1064 continue;
1065 if (load == lowload && pri < lowpri)
1066 continue;
1067 lowcpu = cpu;
1068 lowload = load;
1069 lowpri = pri;
1070 }
1071
1072 return (lowcpu);
1073 }
1074
1075 /*
1076 * Pick the destination cpu for sched_add(). Respects affinity and makes
1077 * a determination based on load or priority of available processors.
1078 */
1079 static int
1080 sched_pickcpu(struct thread *td, int flags)
1081 {
1082 struct tdq *tdq;
1083 struct td_sched *ts;
1084 cpumask_t mask;
1085 int self;
1086 int pri;
1087 int cpu;
1088
1089 self = PCPU_GET(cpuid);
1090 ts = td->td_sched;
1091 if (smp_started == 0)
1092 return (self);
1093 /*
1094 * Don't migrate a running thread from sched_switch().
1095 */
1096 if (flags & SRQ_OURSELF) {
1097 CTR1(KTR_ULE, "YIELDING %d",
1098 curthread->td_priority);
1099 return (self);
1100 }
1101 pri = ts->ts_thread->td_priority;
1102 cpu = ts->ts_cpu;
1103 if (THREAD_CAN_SCHED(td, cpu)) {
1104 /*
1105 * Regardless of affinity, if the last cpu is idle
1106 * send it there.
1107 */
1108 tdq = TDQ_CPU(cpu);
1109 if (tdq->tdq_lowpri > PRI_MIN_IDLE) {
1110 CTR5(KTR_ULE,
1111 "ts_cpu %d idle, ltick %d ticks %d pri %d curthread %d",
1112 ts->ts_cpu, ts->ts_rltick, ticks, pri,
1113 tdq->tdq_lowpri);
1114 return (ts->ts_cpu);
1115 }
1116 /*
1117 * If we have affinity, try to place it on the cpu we
1118 * last ran on.
1119 */
1120 if (SCHED_AFFINITY(ts) && tdq->tdq_lowpri > pri) {
1121 CTR5(KTR_ULE,
1122 "affinity for %d, ltick %d ticks %d pri %d curthread %d",
1123 ts->ts_cpu, ts->ts_rltick, ticks, pri,
1124 tdq->tdq_lowpri);
1125 return (ts->ts_cpu);
1126 }
1127 }
1128
1129 /*
1130 * Look for an idle group.
1131 */
1132 CTR1(KTR_ULE, "tdq_idle %X", tdq_idle);
1133 mask = tdq_idle;
1134 while ((cpu = ffs(mask)) != 0) {
1135 --cpu;
1136 if (THREAD_CAN_SCHED(td, cpu))
1137 return (cpu);
1138 mask &= ~(1 << cpu);
1139 }
1140 /*
1141 * If there are no idle cores see if we can run the thread locally.
1142 * This may improve locality among sleepers and wakers when there
1143 * is shared data.
1144 */
1145 if (tryself && THREAD_CAN_SCHED(td, self) &&
1146 pri < curthread->td_priority) {
1147 CTR1(KTR_ULE, "tryself %d",
1148 curthread->td_priority);
1149 return (self);
1150 }
1151 /*
1152 * Now search for the cpu running the lowest priority thread with
1153 * the least load.
1154 */
1155 if (pick_pri)
1156 cpu = tdq_lowestpri(td);
1157 else
1158 cpu = tdq_lowestload(td);
1159 return (cpu);
1160 }
1161
1162 #endif /* SMP */
1163
1164 /*
1165 * Pick the highest priority task we have and return it.
1166 */
1167 static struct td_sched *
1168 tdq_choose(struct tdq *tdq)
1169 {
1170 struct td_sched *ts;
1171
1172 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
1173 ts = runq_choose(&tdq->tdq_realtime);
1174 if (ts != NULL)
1175 return (ts);
1176 ts = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx);
1177 if (ts != NULL) {
1178 KASSERT(ts->ts_thread->td_priority >= PRI_MIN_TIMESHARE,
1179 ("tdq_choose: Invalid priority on timeshare queue %d",
1180 ts->ts_thread->td_priority));
1181 return (ts);
1182 }
1183
1184 ts = runq_choose(&tdq->tdq_idle);
1185 if (ts != NULL) {
1186 KASSERT(ts->ts_thread->td_priority >= PRI_MIN_IDLE,
1187 ("tdq_choose: Invalid priority on idle queue %d",
1188 ts->ts_thread->td_priority));
1189 return (ts);
1190 }
1191
1192 return (NULL);
1193 }
1194
1195 /*
1196 * Initialize a thread queue.
1197 */
1198 static void
1199 tdq_setup(struct tdq *tdq)
1200 {
1201
1202 if (bootverbose)
1203 printf("ULE: setup cpu %d\n", TDQ_ID(tdq));
1204 runq_init(&tdq->tdq_realtime);
1205 runq_init(&tdq->tdq_timeshare);
1206 runq_init(&tdq->tdq_idle);
1207 tdq->tdq_load = 0;
1208 }
1209
1210 #ifdef SMP
1211 static void
1212 tdg_setup(struct tdq_group *tdg)
1213 {
1214 if (bootverbose)
1215 printf("ULE: setup cpu group %d\n", TDG_ID(tdg));
1216 snprintf(tdg->tdg_name, sizeof(tdg->tdg_name),
1217 "sched lock %d", (int)TDG_ID(tdg));
1218 mtx_init(&tdg->tdg_lock, tdg->tdg_name, "sched lock",
1219 MTX_SPIN | MTX_RECURSE);
1220 LIST_INIT(&tdg->tdg_members);
1221 tdg->tdg_load = 0;
1222 tdg->tdg_transferable = 0;
1223 tdg->tdg_cpus = 0;
1224 tdg->tdg_mask = 0;
1225 tdg->tdg_cpumask = 0;
1226 tdg->tdg_idlemask = 0;
1227 }
1228
1229 static void
1230 tdg_add(struct tdq_group *tdg, struct tdq *tdq)
1231 {
1232 if (tdg->tdg_mask == 0)
1233 tdg->tdg_mask |= 1 << TDQ_ID(tdq);
1234 tdg->tdg_cpumask |= 1 << TDQ_ID(tdq);
1235 tdg->tdg_cpus++;
1236 tdq->tdq_group = tdg;
1237 tdq->tdq_lock = &tdg->tdg_lock;
1238 LIST_INSERT_HEAD(&tdg->tdg_members, tdq, tdq_siblings);
1239 if (bootverbose)
1240 printf("ULE: adding cpu %d to group %d: cpus %d mask 0x%X\n",
1241 TDQ_ID(tdq), TDG_ID(tdg), tdg->tdg_cpus, tdg->tdg_cpumask);
1242 }
1243
1244 static void
1245 sched_setup_topology(void)
1246 {
1247 struct tdq_group *tdg;
1248 struct cpu_group *cg;
1249 int balance_groups;
1250 struct tdq *tdq;
1251 int i;
1252 int j;
1253
1254 topology = 1;
1255 balance_groups = 0;
1256 for (i = 0; i < smp_topology->ct_count; i++) {
1257 cg = &smp_topology->ct_group[i];
1258 tdg = &tdq_groups[i];
1259 /*
1260 * Initialize the group.
1261 */
1262 tdg_setup(tdg);
1263 /*
1264 * Find all of the group members and add them.
1265 */
1266 for (j = 0; j < MAXCPU; j++) {
1267 if ((cg->cg_mask & (1 << j)) != 0) {
1268 tdq = TDQ_CPU(j);
1269 tdq_setup(tdq);
1270 tdg_add(tdg, tdq);
1271 }
1272 }
1273 if (tdg->tdg_cpus > 1)
1274 balance_groups = 1;
1275 }
1276 tdg_maxid = smp_topology->ct_count - 1;
1277 if (balance_groups)
1278 sched_balance_groups();
1279 }
1280
1281 static void
1282 sched_setup_smp(void)
1283 {
1284 struct tdq_group *tdg;
1285 struct tdq *tdq;
1286 int cpus;
1287 int i;
1288
1289 for (cpus = 0, i = 0; i < MAXCPU; i++) {
1290 if (CPU_ABSENT(i))
1291 continue;
1292 tdq = &tdq_cpu[i];
1293 tdg = &tdq_groups[i];
1294 /*
1295 * Setup a tdq group with one member.
1296 */
1297 tdg_setup(tdg);
1298 tdq_setup(tdq);
1299 tdg_add(tdg, tdq);
1300 cpus++;
1301 }
1302 tdg_maxid = cpus - 1;
1303 }
1304
1305 /*
1306 * Fake a topology with one group containing all CPUs.
1307 */
1308 static void
1309 sched_fake_topo(void)
1310 {
1311 #ifdef SCHED_FAKE_TOPOLOGY
1312 static struct cpu_top top;
1313 static struct cpu_group group;
1314
1315 top.ct_count = 1;
1316 top.ct_group = &group;
1317 group.cg_mask = all_cpus;
1318 group.cg_count = mp_ncpus;
1319 group.cg_children = 0;
1320 smp_topology = ⊤
1321 #endif
1322 }
1323 #endif
1324
1325 /*
1326 * Setup the thread queues and initialize the topology based on MD
1327 * information.
1328 */
1329 static void
1330 sched_setup(void *dummy)
1331 {
1332 struct tdq *tdq;
1333
1334 tdq = TDQ_SELF();
1335 #ifdef SMP
1336 sched_fake_topo();
1337 /*
1338 * Setup tdqs based on a topology configuration or vanilla SMP based
1339 * on mp_maxid.
1340 */
1341 if (smp_topology == NULL)
1342 sched_setup_smp();
1343 else
1344 sched_setup_topology();
1345 balance_tdq = tdq;
1346 sched_balance();
1347 #else
1348 tdq_setup(tdq);
1349 mtx_init(&tdq_lock, "sched lock", "sched lock", MTX_SPIN | MTX_RECURSE);
1350 tdq->tdq_lock = &tdq_lock;
1351 #endif
1352 /*
1353 * To avoid divide-by-zero, we set realstathz a dummy value
1354 * in case which sched_clock() called before sched_initticks().
1355 */
1356 realstathz = hz;
1357 sched_slice = (realstathz/10); /* ~100ms */
1358 tickincr = 1 << SCHED_TICK_SHIFT;
1359
1360 /* Add thread0's load since it's running. */
1361 TDQ_LOCK(tdq);
1362 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF());
1363 tdq_load_add(tdq, &td_sched0);
1364 TDQ_UNLOCK(tdq);
1365 }
1366
1367 /*
1368 * This routine determines the tickincr after stathz and hz are setup.
1369 */
1370 /* ARGSUSED */
1371 static void
1372 sched_initticks(void *dummy)
1373 {
1374 int incr;
1375
1376 realstathz = stathz ? stathz : hz;
1377 sched_slice = (realstathz/10); /* ~100ms */
1378
1379 /*
1380 * tickincr is shifted out by 10 to avoid rounding errors due to
1381 * hz not being evenly divisible by stathz on all platforms.
1382 */
1383 incr = (hz << SCHED_TICK_SHIFT) / realstathz;
1384 /*
1385 * This does not work for values of stathz that are more than
1386 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen.
1387 */
1388 if (incr == 0)
1389 incr = 1;
1390 tickincr = incr;
1391 #ifdef SMP
1392 /*
1393 * Set the default balance interval now that we know
1394 * what realstathz is.
1395 */
1396 balance_interval = realstathz;
1397 /*
1398 * Set steal thresh to roughly log2(mp_ncpu) but no greater than 4.
1399 * This prevents excess thrashing on large machines and excess idle
1400 * on smaller machines.
1401 */
1402 steal_thresh = min(fls(mp_ncpus) - 1, 3);
1403 affinity = SCHED_AFFINITY_DEFAULT;
1404 #endif
1405 }
1406
1407
1408 /*
1409 * This is the core of the interactivity algorithm. Determines a score based
1410 * on past behavior. It is the ratio of sleep time to run time scaled to
1411 * a [0, 100] integer. This is the voluntary sleep time of a process, which
1412 * differs from the cpu usage because it does not account for time spent
1413 * waiting on a run-queue. Would be prettier if we had floating point.
1414 */
1415 static int
1416 sched_interact_score(struct thread *td)
1417 {
1418 struct td_sched *ts;
1419 int div;
1420
1421 ts = td->td_sched;
1422 /*
1423 * The score is only needed if this is likely to be an interactive
1424 * task. Don't go through the expense of computing it if there's
1425 * no chance.
1426 */
1427 if (sched_interact <= SCHED_INTERACT_HALF &&
1428 ts->ts_runtime >= ts->ts_slptime)
1429 return (SCHED_INTERACT_HALF);
1430
1431 if (ts->ts_runtime > ts->ts_slptime) {
1432 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF);
1433 return (SCHED_INTERACT_HALF +
1434 (SCHED_INTERACT_HALF - (ts->ts_slptime / div)));
1435 }
1436 if (ts->ts_slptime > ts->ts_runtime) {
1437 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF);
1438 return (ts->ts_runtime / div);
1439 }
1440 /* runtime == slptime */
1441 if (ts->ts_runtime)
1442 return (SCHED_INTERACT_HALF);
1443
1444 /*
1445 * This can happen if slptime and runtime are 0.
1446 */
1447 return (0);
1448
1449 }
1450
1451 /*
1452 * Scale the scheduling priority according to the "interactivity" of this
1453 * process.
1454 */
1455 static void
1456 sched_priority(struct thread *td)
1457 {
1458 int score;
1459 int pri;
1460
1461 if (td->td_pri_class != PRI_TIMESHARE)
1462 return;
1463 /*
1464 * If the score is interactive we place the thread in the realtime
1465 * queue with a priority that is less than kernel and interrupt
1466 * priorities. These threads are not subject to nice restrictions.
1467 *
1468 * Scores greater than this are placed on the normal timeshare queue
1469 * where the priority is partially decided by the most recent cpu
1470 * utilization and the rest is decided by nice value.
1471 *
1472 * The nice value of the process has a linear effect on the calculated
1473 * score. Negative nice values make it easier for a thread to be
1474 * considered interactive.
1475 */
1476 score = imax(0, sched_interact_score(td) - td->td_proc->p_nice);
1477 if (score < sched_interact) {
1478 pri = PRI_MIN_REALTIME;
1479 pri += ((PRI_MAX_REALTIME - PRI_MIN_REALTIME) / sched_interact)
1480 * score;
1481 KASSERT(pri >= PRI_MIN_REALTIME && pri <= PRI_MAX_REALTIME,
1482 ("sched_priority: invalid interactive priority %d score %d",
1483 pri, score));
1484 } else {
1485 pri = SCHED_PRI_MIN;
1486 if (td->td_sched->ts_ticks)
1487 pri += SCHED_PRI_TICKS(td->td_sched);
1488 pri += SCHED_PRI_NICE(td->td_proc->p_nice);
1489 KASSERT(pri >= PRI_MIN_TIMESHARE && pri <= PRI_MAX_TIMESHARE,
1490 ("sched_priority: invalid priority %d: nice %d, "
1491 "ticks %d ftick %d ltick %d tick pri %d",
1492 pri, td->td_proc->p_nice, td->td_sched->ts_ticks,
1493 td->td_sched->ts_ftick, td->td_sched->ts_ltick,
1494 SCHED_PRI_TICKS(td->td_sched)));
1495 }
1496 sched_user_prio(td, pri);
1497
1498 return;
1499 }
1500
1501 /*
1502 * This routine enforces a maximum limit on the amount of scheduling history
1503 * kept. It is called after either the slptime or runtime is adjusted. This
1504 * function is ugly due to integer math.
1505 */
1506 static void
1507 sched_interact_update(struct thread *td)
1508 {
1509 struct td_sched *ts;
1510 u_int sum;
1511
1512 ts = td->td_sched;
1513 sum = ts->ts_runtime + ts->ts_slptime;
1514 if (sum < SCHED_SLP_RUN_MAX)
1515 return;
1516 /*
1517 * This only happens from two places:
1518 * 1) We have added an unusual amount of run time from fork_exit.
1519 * 2) We have added an unusual amount of sleep time from sched_sleep().
1520 */
1521 if (sum > SCHED_SLP_RUN_MAX * 2) {
1522 if (ts->ts_runtime > ts->ts_slptime) {
1523 ts->ts_runtime = SCHED_SLP_RUN_MAX;
1524 ts->ts_slptime = 1;
1525 } else {
1526 ts->ts_slptime = SCHED_SLP_RUN_MAX;
1527 ts->ts_runtime = 1;
1528 }
1529 return;
1530 }
1531 /*
1532 * If we have exceeded by more than 1/5th then the algorithm below
1533 * will not bring us back into range. Dividing by two here forces
1534 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX]
1535 */
1536 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) {
1537 ts->ts_runtime /= 2;
1538 ts->ts_slptime /= 2;
1539 return;
1540 }
1541 ts->ts_runtime = (ts->ts_runtime / 5) * 4;
1542 ts->ts_slptime = (ts->ts_slptime / 5) * 4;
1543 }
1544
1545 /*
1546 * Scale back the interactivity history when a child thread is created. The
1547 * history is inherited from the parent but the thread may behave totally
1548 * differently. For example, a shell spawning a compiler process. We want
1549 * to learn that the compiler is behaving badly very quickly.
1550 */
1551 static void
1552 sched_interact_fork(struct thread *td)
1553 {
1554 int ratio;
1555 int sum;
1556
1557 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime;
1558 if (sum > SCHED_SLP_RUN_FORK) {
1559 ratio = sum / SCHED_SLP_RUN_FORK;
1560 td->td_sched->ts_runtime /= ratio;
1561 td->td_sched->ts_slptime /= ratio;
1562 }
1563 }
1564
1565 /*
1566 * Called from proc0_init() to setup the scheduler fields.
1567 */
1568 void
1569 schedinit(void)
1570 {
1571
1572 /*
1573 * Set up the scheduler specific parts of proc0.
1574 */
1575 proc0.p_sched = NULL; /* XXX */
1576 thread0.td_sched = &td_sched0;
1577 td_sched0.ts_ltick = ticks;
1578 td_sched0.ts_ftick = ticks;
1579 td_sched0.ts_thread = &thread0;
1580 }
1581
1582 /*
1583 * This is only somewhat accurate since given many processes of the same
1584 * priority they will switch when their slices run out, which will be
1585 * at most sched_slice stathz ticks.
1586 */
1587 int
1588 sched_rr_interval(void)
1589 {
1590
1591 /* Convert sched_slice to hz */
1592 return (hz/(realstathz/sched_slice));
1593 }
1594
1595 /*
1596 * Update the percent cpu tracking information when it is requested or
1597 * the total history exceeds the maximum. We keep a sliding history of
1598 * tick counts that slowly decays. This is less precise than the 4BSD
1599 * mechanism since it happens with less regular and frequent events.
1600 */
1601 static void
1602 sched_pctcpu_update(struct td_sched *ts)
1603 {
1604
1605 if (ts->ts_ticks == 0)
1606 return;
1607 if (ticks - (hz / 10) < ts->ts_ltick &&
1608 SCHED_TICK_TOTAL(ts) < SCHED_TICK_MAX)
1609 return;
1610 /*
1611 * Adjust counters and watermark for pctcpu calc.
1612 */
1613 if (ts->ts_ltick > ticks - SCHED_TICK_TARG)
1614 ts->ts_ticks = (ts->ts_ticks / (ticks - ts->ts_ftick)) *
1615 SCHED_TICK_TARG;
1616 else
1617 ts->ts_ticks = 0;
1618 ts->ts_ltick = ticks;
1619 ts->ts_ftick = ts->ts_ltick - SCHED_TICK_TARG;
1620 }
1621
1622 /*
1623 * Adjust the priority of a thread. Move it to the appropriate run-queue
1624 * if necessary. This is the back-end for several priority related
1625 * functions.
1626 */
1627 static void
1628 sched_thread_priority(struct thread *td, u_char prio)
1629 {
1630 struct td_sched *ts;
1631
1632 CTR6(KTR_SCHED, "sched_prio: %p(%s) prio %d newprio %d by %p(%s)",
1633 td, td->td_proc->p_comm, td->td_priority, prio, curthread,
1634 curthread->td_proc->p_comm);
1635 ts = td->td_sched;
1636 THREAD_LOCK_ASSERT(td, MA_OWNED);
1637 if (td->td_priority == prio)
1638 return;
1639
1640 if (TD_ON_RUNQ(td) && prio < td->td_priority) {
1641 /*
1642 * If the priority has been elevated due to priority
1643 * propagation, we may have to move ourselves to a new
1644 * queue. This could be optimized to not re-add in some
1645 * cases.
1646 */
1647 sched_rem(td);
1648 td->td_priority = prio;
1649 sched_add(td, SRQ_BORROWING);
1650 } else {
1651 #ifdef SMP
1652 struct tdq *tdq;
1653
1654 tdq = TDQ_CPU(ts->ts_cpu);
1655 if (prio < tdq->tdq_lowpri)
1656 tdq->tdq_lowpri = prio;
1657 #endif
1658 td->td_priority = prio;
1659 }
1660 }
1661
1662 /*
1663 * Update a thread's priority when it is lent another thread's
1664 * priority.
1665 */
1666 void
1667 sched_lend_prio(struct thread *td, u_char prio)
1668 {
1669
1670 td->td_flags |= TDF_BORROWING;
1671 sched_thread_priority(td, prio);
1672 }
1673
1674 /*
1675 * Restore a thread's priority when priority propagation is
1676 * over. The prio argument is the minimum priority the thread
1677 * needs to have to satisfy other possible priority lending
1678 * requests. If the thread's regular priority is less
1679 * important than prio, the thread will keep a priority boost
1680 * of prio.
1681 */
1682 void
1683 sched_unlend_prio(struct thread *td, u_char prio)
1684 {
1685 u_char base_pri;
1686
1687 if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
1688 td->td_base_pri <= PRI_MAX_TIMESHARE)
1689 base_pri = td->td_user_pri;
1690 else
1691 base_pri = td->td_base_pri;
1692 if (prio >= base_pri) {
1693 td->td_flags &= ~TDF_BORROWING;
1694 sched_thread_priority(td, base_pri);
1695 } else
1696 sched_lend_prio(td, prio);
1697 }
1698
1699 /*
1700 * Standard entry for setting the priority to an absolute value.
1701 */
1702 void
1703 sched_prio(struct thread *td, u_char prio)
1704 {
1705 u_char oldprio;
1706
1707 /* First, update the base priority. */
1708 td->td_base_pri = prio;
1709
1710 /*
1711 * If the thread is borrowing another thread's priority, don't
1712 * ever lower the priority.
1713 */
1714 if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
1715 return;
1716
1717 /* Change the real priority. */
1718 oldprio = td->td_priority;
1719 sched_thread_priority(td, prio);
1720
1721 /*
1722 * If the thread is on a turnstile, then let the turnstile update
1723 * its state.
1724 */
1725 if (TD_ON_LOCK(td) && oldprio != prio)
1726 turnstile_adjust(td, oldprio);
1727 }
1728
1729 /*
1730 * Set the base user priority, does not effect current running priority.
1731 */
1732 void
1733 sched_user_prio(struct thread *td, u_char prio)
1734 {
1735 u_char oldprio;
1736
1737 td->td_base_user_pri = prio;
1738 if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio)
1739 return;
1740 oldprio = td->td_user_pri;
1741 td->td_user_pri = prio;
1742 }
1743
1744 void
1745 sched_lend_user_prio(struct thread *td, u_char prio)
1746 {
1747 u_char oldprio;
1748
1749 THREAD_LOCK_ASSERT(td, MA_OWNED);
1750 td->td_flags |= TDF_UBORROWING;
1751 oldprio = td->td_user_pri;
1752 td->td_user_pri = prio;
1753 }
1754
1755 void
1756 sched_unlend_user_prio(struct thread *td, u_char prio)
1757 {
1758 u_char base_pri;
1759
1760 THREAD_LOCK_ASSERT(td, MA_OWNED);
1761 base_pri = td->td_base_user_pri;
1762 if (prio >= base_pri) {
1763 td->td_flags &= ~TDF_UBORROWING;
1764 sched_user_prio(td, base_pri);
1765 } else {
1766 sched_lend_user_prio(td, prio);
1767 }
1768 }
1769
1770 /*
1771 * Add the thread passed as 'newtd' to the run queue before selecting
1772 * the next thread to run. This is only used for KSE.
1773 */
1774 static void
1775 sched_switchin(struct tdq *tdq, struct thread *td)
1776 {
1777 #ifdef SMP
1778 spinlock_enter();
1779 TDQ_UNLOCK(tdq);
1780 thread_lock(td);
1781 spinlock_exit();
1782 sched_setcpu(td->td_sched, TDQ_ID(tdq), SRQ_YIELDING);
1783 #else
1784 td->td_lock = TDQ_LOCKPTR(tdq);
1785 #endif
1786 tdq_add(tdq, td, SRQ_YIELDING);
1787 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1788 }
1789
1790 /*
1791 * Block a thread for switching. Similar to thread_block() but does not
1792 * bump the spin count.
1793 */
1794 static inline struct mtx *
1795 thread_block_switch(struct thread *td)
1796 {
1797 struct mtx *lock;
1798
1799 THREAD_LOCK_ASSERT(td, MA_OWNED);
1800 lock = td->td_lock;
1801 td->td_lock = &blocked_lock;
1802 mtx_unlock_spin(lock);
1803
1804 return (lock);
1805 }
1806
1807 /*
1808 * Handle migration from sched_switch(). This happens only for
1809 * cpu binding.
1810 */
1811 static struct mtx *
1812 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags)
1813 {
1814 struct tdq *tdn;
1815
1816 tdn = TDQ_CPU(td->td_sched->ts_cpu);
1817 #ifdef SMP
1818 /*
1819 * Do the lock dance required to avoid LOR. We grab an extra
1820 * spinlock nesting to prevent preemption while we're
1821 * not holding either run-queue lock.
1822 */
1823 spinlock_enter();
1824 thread_block_switch(td); /* This releases the lock on tdq. */
1825
1826 /*
1827 * Acquire both run-queue locks before placing the thread on the new
1828 * run-queue to avoid deadlocks created by placing a thread with a
1829 * blocked lock on the run-queue of a remote processor. The deadlock
1830 * occurs when a third processor attempts to lock the two queues in
1831 * question while the target processor is spinning with its own
1832 * run-queue lock held while waiting for the blocked lock to clear.
1833 */
1834 if (TDQ_LOCKPTR(tdn) == TDQ_LOCKPTR(tdq)) {
1835 TDQ_LOCK(tdq);
1836 tdq_add(tdn, td, flags);
1837 tdq_notify(td->td_sched);
1838 } else {
1839 tdq_lock_pair(tdn, tdq);
1840 tdq_add(tdn, td, flags);
1841 tdq_notify(td->td_sched);
1842 TDQ_UNLOCK(tdn);
1843 }
1844 spinlock_exit();
1845 #endif
1846 return (TDQ_LOCKPTR(tdn));
1847 }
1848
1849 /*
1850 * Release a thread that was blocked with thread_block_switch().
1851 */
1852 static inline void
1853 thread_unblock_switch(struct thread *td, struct mtx *mtx)
1854 {
1855 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock,
1856 (uintptr_t)mtx);
1857 }
1858
1859 /*
1860 * Switch threads. This function has to handle threads coming in while
1861 * blocked for some reason, running, or idle. It also must deal with
1862 * migrating a thread from one queue to another as running threads may
1863 * be assigned elsewhere via binding.
1864 */
1865 void
1866 sched_switch(struct thread *td, struct thread *newtd, int flags)
1867 {
1868 struct tdq *tdq;
1869 struct td_sched *ts;
1870 struct mtx *mtx;
1871 int srqflag;
1872 int cpuid;
1873
1874 THREAD_LOCK_ASSERT(td, MA_OWNED);
1875
1876 cpuid = PCPU_GET(cpuid);
1877 tdq = TDQ_CPU(cpuid);
1878 ts = td->td_sched;
1879 mtx = td->td_lock;
1880 #ifdef SMP
1881 ts->ts_rltick = ticks;
1882 if (newtd && newtd->td_priority < tdq->tdq_lowpri)
1883 tdq->tdq_lowpri = newtd->td_priority;
1884 #endif
1885 td->td_lastcpu = td->td_oncpu;
1886 td->td_oncpu = NOCPU;
1887 td->td_flags &= ~TDF_NEEDRESCHED;
1888 td->td_owepreempt = 0;
1889 /*
1890 * The lock pointer in an idle thread should never change. Reset it
1891 * to CAN_RUN as well.
1892 */
1893 if (TD_IS_IDLETHREAD(td)) {
1894 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1895 TD_SET_CAN_RUN(td);
1896 } else if (TD_IS_RUNNING(td)) {
1897 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1898 tdq_load_rem(tdq, ts);
1899 srqflag = (flags & SW_PREEMPT) ?
1900 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
1901 SRQ_OURSELF|SRQ_YIELDING;
1902 if (ts->ts_cpu == cpuid)
1903 tdq_add(tdq, td, srqflag);
1904 else
1905 mtx = sched_switch_migrate(tdq, td, srqflag);
1906 } else {
1907 /* This thread must be going to sleep. */
1908 TDQ_LOCK(tdq);
1909 mtx = thread_block_switch(td);
1910 tdq_load_rem(tdq, ts);
1911 }
1912 /*
1913 * We enter here with the thread blocked and assigned to the
1914 * appropriate cpu run-queue or sleep-queue and with the current
1915 * thread-queue locked.
1916 */
1917 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
1918 /*
1919 * If KSE assigned a new thread just add it here and let choosethread
1920 * select the best one.
1921 */
1922 if (newtd != NULL)
1923 sched_switchin(tdq, newtd);
1924 newtd = choosethread();
1925 /*
1926 * Call the MD code to switch contexts if necessary.
1927 */
1928 if (td != newtd) {
1929 #ifdef HWPMC_HOOKS
1930 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1931 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
1932 #endif
1933 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
1934
1935 #ifdef KDTRACE_HOOKS
1936 /*
1937 * If DTrace has set the active vtime enum to anything
1938 * other than INACTIVE (0), then it should have set the
1939 * function to call.
1940 */
1941 if (dtrace_vtime_active)
1942 (*dtrace_vtime_switch_func)(newtd);
1943 #endif
1944 cpu_switch(td, newtd, mtx);
1945 /*
1946 * We may return from cpu_switch on a different cpu. However,
1947 * we always return with td_lock pointing to the current cpu's
1948 * run queue lock.
1949 */
1950 cpuid = PCPU_GET(cpuid);
1951 tdq = TDQ_CPU(cpuid);
1952 #ifdef HWPMC_HOOKS
1953 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1954 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
1955 #endif
1956 } else
1957 thread_unblock_switch(td, mtx);
1958 /*
1959 * Assert that all went well and return.
1960 */
1961 #ifdef SMP
1962 /* We should always get here with the lowest priority td possible */
1963 tdq->tdq_lowpri = td->td_priority;
1964 #endif
1965 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED);
1966 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1967 td->td_oncpu = cpuid;
1968 }
1969
1970 /*
1971 * Adjust thread priorities as a result of a nice request.
1972 */
1973 void
1974 sched_nice(struct proc *p, int nice)
1975 {
1976 struct thread *td;
1977
1978 PROC_LOCK_ASSERT(p, MA_OWNED);
1979 PROC_SLOCK_ASSERT(p, MA_OWNED);
1980
1981 p->p_nice = nice;
1982 FOREACH_THREAD_IN_PROC(p, td) {
1983 thread_lock(td);
1984 sched_priority(td);
1985 sched_prio(td, td->td_base_user_pri);
1986 thread_unlock(td);
1987 }
1988 }
1989
1990 /*
1991 * Record the sleep time for the interactivity scorer.
1992 */
1993 void
1994 sched_sleep(struct thread *td)
1995 {
1996
1997 THREAD_LOCK_ASSERT(td, MA_OWNED);
1998
1999 td->td_slptick = ticks;
2000 }
2001
2002 /*
2003 * Schedule a thread to resume execution and record how long it voluntarily
2004 * slept. We also update the pctcpu, interactivity, and priority.
2005 */
2006 void
2007 sched_wakeup(struct thread *td)
2008 {
2009 struct td_sched *ts;
2010 int slptick;
2011
2012 THREAD_LOCK_ASSERT(td, MA_OWNED);
2013 ts = td->td_sched;
2014 /*
2015 * If we slept for more than a tick update our interactivity and
2016 * priority.
2017 */
2018 slptick = td->td_slptick;
2019 td->td_slptick = 0;
2020 if (slptick && slptick != ticks) {
2021 u_int hzticks;
2022
2023 hzticks = (ticks - slptick) << SCHED_TICK_SHIFT;
2024 ts->ts_slptime += hzticks;
2025 sched_interact_update(td);
2026 sched_pctcpu_update(ts);
2027 sched_priority(td);
2028 }
2029 /* Reset the slice value after we sleep. */
2030 ts->ts_slice = sched_slice;
2031 sched_add(td, SRQ_BORING);
2032 }
2033
2034 /*
2035 * Penalize the parent for creating a new child and initialize the child's
2036 * priority.
2037 */
2038 void
2039 sched_fork(struct thread *td, struct thread *child)
2040 {
2041 THREAD_LOCK_ASSERT(td, MA_OWNED);
2042 sched_fork_thread(td, child);
2043 /*
2044 * Penalize the parent and child for forking.
2045 */
2046 sched_interact_fork(child);
2047 sched_priority(child);
2048 td->td_sched->ts_runtime += tickincr;
2049 sched_interact_update(td);
2050 sched_priority(td);
2051 }
2052
2053 /*
2054 * Fork a new thread, may be within the same process.
2055 */
2056 void
2057 sched_fork_thread(struct thread *td, struct thread *child)
2058 {
2059 struct td_sched *ts;
2060 struct td_sched *ts2;
2061
2062 /*
2063 * Initialize child.
2064 */
2065 THREAD_LOCK_ASSERT(td, MA_OWNED);
2066 sched_newthread(child);
2067 child->td_lock = TDQ_LOCKPTR(TDQ_SELF());
2068 child->td_cpuset = cpuset_ref(td->td_cpuset);
2069 ts = td->td_sched;
2070 ts2 = child->td_sched;
2071 ts2->ts_cpu = ts->ts_cpu;
2072 ts2->ts_runq = NULL;
2073 /*
2074 * Grab our parents cpu estimation information and priority.
2075 */
2076 ts2->ts_ticks = ts->ts_ticks;
2077 ts2->ts_ltick = ts->ts_ltick;
2078 ts2->ts_ftick = ts->ts_ftick;
2079 child->td_user_pri = td->td_user_pri;
2080 child->td_base_user_pri = td->td_base_user_pri;
2081 /*
2082 * And update interactivity score.
2083 */
2084 ts2->ts_slptime = ts->ts_slptime;
2085 ts2->ts_runtime = ts->ts_runtime;
2086 ts2->ts_slice = 1; /* Attempt to quickly learn interactivity. */
2087 }
2088
2089 /*
2090 * Adjust the priority class of a thread.
2091 */
2092 void
2093 sched_class(struct thread *td, int class)
2094 {
2095
2096 THREAD_LOCK_ASSERT(td, MA_OWNED);
2097 if (td->td_pri_class == class)
2098 return;
2099
2100 #ifdef SMP
2101 /*
2102 * On SMP if we're on the RUNQ we must adjust the transferable
2103 * count because could be changing to or from an interrupt
2104 * class.
2105 */
2106 if (TD_ON_RUNQ(td)) {
2107 struct tdq *tdq;
2108
2109 tdq = TDQ_CPU(td->td_sched->ts_cpu);
2110 if (THREAD_CAN_MIGRATE(td)) {
2111 tdq->tdq_transferable--;
2112 tdq->tdq_group->tdg_transferable--;
2113 }
2114 td->td_pri_class = class;
2115 if (THREAD_CAN_MIGRATE(td)) {
2116 tdq->tdq_transferable++;
2117 tdq->tdq_group->tdg_transferable++;
2118 }
2119 }
2120 #endif
2121 td->td_pri_class = class;
2122 }
2123
2124 /*
2125 * Return some of the child's priority and interactivity to the parent.
2126 */
2127 void
2128 sched_exit(struct proc *p, struct thread *child)
2129 {
2130 struct thread *td;
2131
2132 CTR3(KTR_SCHED, "sched_exit: %p(%s) prio %d",
2133 child, child->td_proc->p_comm, child->td_priority);
2134
2135 PROC_SLOCK_ASSERT(p, MA_OWNED);
2136 td = FIRST_THREAD_IN_PROC(p);
2137 sched_exit_thread(td, child);
2138 }
2139
2140 /*
2141 * Penalize another thread for the time spent on this one. This helps to
2142 * worsen the priority and interactivity of processes which schedule batch
2143 * jobs such as make. This has little effect on the make process itself but
2144 * causes new processes spawned by it to receive worse scores immediately.
2145 */
2146 void
2147 sched_exit_thread(struct thread *td, struct thread *child)
2148 {
2149
2150 CTR3(KTR_SCHED, "sched_exit_thread: %p(%s) prio %d",
2151 child, child->td_proc->p_comm, child->td_priority);
2152
2153 #ifdef KSE
2154 /*
2155 * KSE forks and exits so often that this penalty causes short-lived
2156 * threads to always be non-interactive. This causes mozilla to
2157 * crawl under load.
2158 */
2159 if ((td->td_pflags & TDP_SA) && td->td_proc == child->td_proc)
2160 return;
2161 #endif
2162 /*
2163 * Give the child's runtime to the parent without returning the
2164 * sleep time as a penalty to the parent. This causes shells that
2165 * launch expensive things to mark their children as expensive.
2166 */
2167 thread_lock(td);
2168 td->td_sched->ts_runtime += child->td_sched->ts_runtime;
2169 sched_interact_update(td);
2170 sched_priority(td);
2171 thread_unlock(td);
2172 }
2173
2174 /*
2175 * Fix priorities on return to user-space. Priorities may be elevated due
2176 * to static priorities in msleep() or similar.
2177 */
2178 void
2179 sched_userret(struct thread *td)
2180 {
2181 /*
2182 * XXX we cheat slightly on the locking here to avoid locking in
2183 * the usual case. Setting td_priority here is essentially an
2184 * incomplete workaround for not setting it properly elsewhere.
2185 * Now that some interrupt handlers are threads, not setting it
2186 * properly elsewhere can clobber it in the window between setting
2187 * it here and returning to user mode, so don't waste time setting
2188 * it perfectly here.
2189 */
2190 KASSERT((td->td_flags & TDF_BORROWING) == 0,
2191 ("thread with borrowed priority returning to userland"));
2192 if (td->td_priority != td->td_user_pri) {
2193 thread_lock(td);
2194 td->td_priority = td->td_user_pri;
2195 td->td_base_pri = td->td_user_pri;
2196 thread_unlock(td);
2197 }
2198 }
2199
2200 /*
2201 * Handle a stathz tick. This is really only relevant for timeshare
2202 * threads.
2203 */
2204 void
2205 sched_clock(struct thread *td)
2206 {
2207 struct tdq *tdq;
2208 struct td_sched *ts;
2209
2210 THREAD_LOCK_ASSERT(td, MA_OWNED);
2211 tdq = TDQ_SELF();
2212 #ifdef SMP
2213 /*
2214 * We run the long term load balancer infrequently on the first cpu.
2215 */
2216 if (balance_tdq == tdq) {
2217 if (balance_ticks && --balance_ticks == 0)
2218 sched_balance();
2219 if (balance_group_ticks && --balance_group_ticks == 0)
2220 sched_balance_groups();
2221 }
2222 #endif
2223 /*
2224 * Advance the insert index once for each tick to ensure that all
2225 * threads get a chance to run.
2226 */
2227 if (tdq->tdq_idx == tdq->tdq_ridx) {
2228 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS;
2229 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx]))
2230 tdq->tdq_ridx = tdq->tdq_idx;
2231 }
2232 ts = td->td_sched;
2233 if (td->td_pri_class & PRI_FIFO_BIT)
2234 return;
2235 if (td->td_pri_class == PRI_TIMESHARE) {
2236 /*
2237 * We used a tick; charge it to the thread so
2238 * that we can compute our interactivity.
2239 */
2240 td->td_sched->ts_runtime += tickincr;
2241 sched_interact_update(td);
2242 }
2243 /*
2244 * We used up one time slice.
2245 */
2246 if (--ts->ts_slice > 0)
2247 return;
2248 /*
2249 * We're out of time, recompute priorities and requeue.
2250 */
2251 sched_priority(td);
2252 td->td_flags |= TDF_NEEDRESCHED;
2253 }
2254
2255 /*
2256 * Called once per hz tick. Used for cpu utilization information. This
2257 * is easier than trying to scale based on stathz.
2258 */
2259 void
2260 sched_tick(void)
2261 {
2262 struct td_sched *ts;
2263
2264 ts = curthread->td_sched;
2265 /*
2266 * Ticks is updated asynchronously on a single cpu. Check here to
2267 * avoid incrementing ts_ticks multiple times in a single tick.
2268 */
2269 if (ts->ts_ltick == ticks)
2270 return;
2271 /* Adjust ticks for pctcpu */
2272 ts->ts_ticks += 1 << SCHED_TICK_SHIFT;
2273 ts->ts_ltick = ticks;
2274 /*
2275 * Update if we've exceeded our desired tick threshhold by over one
2276 * second.
2277 */
2278 if (ts->ts_ftick + SCHED_TICK_MAX < ts->ts_ltick)
2279 sched_pctcpu_update(ts);
2280 }
2281
2282 /*
2283 * Return whether the current CPU has runnable tasks. Used for in-kernel
2284 * cooperative idle threads.
2285 */
2286 int
2287 sched_runnable(void)
2288 {
2289 struct tdq *tdq;
2290 int load;
2291
2292 load = 1;
2293
2294 tdq = TDQ_SELF();
2295 if ((curthread->td_flags & TDF_IDLETD) != 0) {
2296 if (tdq->tdq_load > 0)
2297 goto out;
2298 } else
2299 if (tdq->tdq_load - 1 > 0)
2300 goto out;
2301 load = 0;
2302 out:
2303 return (load);
2304 }
2305
2306 /*
2307 * Choose the highest priority thread to run. The thread is removed from
2308 * the run-queue while running however the load remains. For SMP we set
2309 * the tdq in the global idle bitmask if it idles here.
2310 */
2311 struct thread *
2312 sched_choose(void)
2313 {
2314 #ifdef SMP
2315 struct tdq_group *tdg;
2316 #endif
2317 struct td_sched *ts;
2318 struct tdq *tdq;
2319
2320 tdq = TDQ_SELF();
2321 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2322 ts = tdq_choose(tdq);
2323 if (ts) {
2324 tdq_runq_rem(tdq, ts);
2325 return (ts->ts_thread);
2326 }
2327 #ifdef SMP
2328 /*
2329 * We only set the idled bit when all of the cpus in the group are
2330 * idle. Otherwise we could get into a situation where a thread bounces
2331 * back and forth between two idle cores on seperate physical CPUs.
2332 */
2333 tdg = tdq->tdq_group;
2334 tdg->tdg_idlemask |= PCPU_GET(cpumask);
2335 if (tdg->tdg_idlemask == tdg->tdg_cpumask)
2336 atomic_set_int(&tdq_idle, tdg->tdg_mask);
2337 tdq->tdq_lowpri = PRI_MAX_IDLE;
2338 #endif
2339 return (PCPU_GET(idlethread));
2340 }
2341
2342 /*
2343 * Set owepreempt if necessary. Preemption never happens directly in ULE,
2344 * we always request it once we exit a critical section.
2345 */
2346 static inline void
2347 sched_setpreempt(struct thread *td)
2348 {
2349 struct thread *ctd;
2350 int cpri;
2351 int pri;
2352
2353 ctd = curthread;
2354 pri = td->td_priority;
2355 cpri = ctd->td_priority;
2356 if (td->td_priority < ctd->td_priority)
2357 curthread->td_flags |= TDF_NEEDRESCHED;
2358 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd))
2359 return;
2360 /*
2361 * Always preempt IDLE threads. Otherwise only if the preempting
2362 * thread is an ithread.
2363 */
2364 if (pri > preempt_thresh && cpri < PRI_MIN_IDLE)
2365 return;
2366 ctd->td_owepreempt = 1;
2367 return;
2368 }
2369
2370 /*
2371 * Add a thread to a thread queue. Initializes priority, slice, runq, and
2372 * add it to the appropriate queue. This is the internal function called
2373 * when the tdq is predetermined.
2374 */
2375 void
2376 tdq_add(struct tdq *tdq, struct thread *td, int flags)
2377 {
2378 struct td_sched *ts;
2379 int class;
2380 #ifdef SMP
2381 int cpumask;
2382 #endif
2383
2384 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2385 KASSERT((td->td_inhibitors == 0),
2386 ("sched_add: trying to run inhibited thread"));
2387 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
2388 ("sched_add: bad thread state"));
2389 KASSERT(td->td_flags & TDF_INMEM,
2390 ("sched_add: thread swapped out"));
2391
2392 ts = td->td_sched;
2393 class = PRI_BASE(td->td_pri_class);
2394 TD_SET_RUNQ(td);
2395 if (ts->ts_slice == 0)
2396 ts->ts_slice = sched_slice;
2397 /*
2398 * Pick the run queue based on priority.
2399 */
2400 if (td->td_priority <= PRI_MAX_REALTIME)
2401 ts->ts_runq = &tdq->tdq_realtime;
2402 else if (td->td_priority <= PRI_MAX_TIMESHARE)
2403 ts->ts_runq = &tdq->tdq_timeshare;
2404 else
2405 ts->ts_runq = &tdq->tdq_idle;
2406 #ifdef SMP
2407 cpumask = 1 << ts->ts_cpu;
2408 /*
2409 * If we had been idle, clear our bit in the group and potentially
2410 * the global bitmap.
2411 */
2412 if ((class != PRI_IDLE && class != PRI_ITHD) &&
2413 (tdq->tdq_group->tdg_idlemask & cpumask) != 0) {
2414 /*
2415 * Check to see if our group is unidling, and if so, remove it
2416 * from the global idle mask.
2417 */
2418 if (tdq->tdq_group->tdg_idlemask ==
2419 tdq->tdq_group->tdg_cpumask)
2420 atomic_clear_int(&tdq_idle, tdq->tdq_group->tdg_mask);
2421 /*
2422 * Now remove ourselves from the group specific idle mask.
2423 */
2424 tdq->tdq_group->tdg_idlemask &= ~cpumask;
2425 }
2426 if (td->td_priority < tdq->tdq_lowpri)
2427 tdq->tdq_lowpri = td->td_priority;
2428 #endif
2429 tdq_runq_add(tdq, ts, flags);
2430 tdq_load_add(tdq, ts);
2431 }
2432
2433 /*
2434 * Select the target thread queue and add a thread to it. Request
2435 * preemption or IPI a remote processor if required.
2436 */
2437 void
2438 sched_add(struct thread *td, int flags)
2439 {
2440 struct td_sched *ts;
2441 struct tdq *tdq;
2442 #ifdef SMP
2443 int cpuid;
2444 int cpu;
2445 #endif
2446 CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)",
2447 td, td->td_proc->p_comm, td->td_priority, curthread,
2448 curthread->td_proc->p_comm);
2449 THREAD_LOCK_ASSERT(td, MA_OWNED);
2450 ts = td->td_sched;
2451 /*
2452 * Recalculate the priority before we select the target cpu or
2453 * run-queue.
2454 */
2455 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
2456 sched_priority(td);
2457 #ifdef SMP
2458 cpuid = PCPU_GET(cpuid);
2459 /*
2460 * Pick the destination cpu and if it isn't ours transfer to the
2461 * target cpu.
2462 */
2463 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_MIGRATE(td) &&
2464 curthread->td_intr_nesting_level)
2465 ts->ts_cpu = cpuid;
2466 if (!THREAD_CAN_MIGRATE(td))
2467 cpu = ts->ts_cpu;
2468 else
2469 cpu = sched_pickcpu(td, flags);
2470 tdq = sched_setcpu(ts, cpu, flags);
2471 tdq_add(tdq, td, flags);
2472 if (cpu != cpuid) {
2473 tdq_notify(ts);
2474 return;
2475 }
2476 #else
2477 tdq = TDQ_SELF();
2478 TDQ_LOCK(tdq);
2479 /*
2480 * Now that the thread is moving to the run-queue, set the lock
2481 * to the scheduler's lock.
2482 */
2483 thread_lock_set(td, TDQ_LOCKPTR(tdq));
2484 tdq_add(tdq, td, flags);
2485 #endif
2486 if (!(flags & SRQ_YIELDING))
2487 sched_setpreempt(td);
2488 }
2489
2490 /*
2491 * Remove a thread from a run-queue without running it. This is used
2492 * when we're stealing a thread from a remote queue. Otherwise all threads
2493 * exit by calling sched_exit_thread() and sched_throw() themselves.
2494 */
2495 void
2496 sched_rem(struct thread *td)
2497 {
2498 struct tdq *tdq;
2499 struct td_sched *ts;
2500
2501 CTR5(KTR_SCHED, "sched_rem: %p(%s) prio %d by %p(%s)",
2502 td, td->td_proc->p_comm, td->td_priority, curthread,
2503 curthread->td_proc->p_comm);
2504 ts = td->td_sched;
2505 tdq = TDQ_CPU(ts->ts_cpu);
2506 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2507 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2508 KASSERT(TD_ON_RUNQ(td),
2509 ("sched_rem: thread not on run queue"));
2510 tdq_runq_rem(tdq, ts);
2511 tdq_load_rem(tdq, ts);
2512 TD_SET_CAN_RUN(td);
2513 }
2514
2515 /*
2516 * Fetch cpu utilization information. Updates on demand.
2517 */
2518 fixpt_t
2519 sched_pctcpu(struct thread *td)
2520 {
2521 fixpt_t pctcpu;
2522 struct td_sched *ts;
2523
2524 pctcpu = 0;
2525 ts = td->td_sched;
2526 if (ts == NULL)
2527 return (0);
2528
2529 thread_lock(td);
2530 if (ts->ts_ticks) {
2531 int rtick;
2532
2533 sched_pctcpu_update(ts);
2534 /* How many rtick per second ? */
2535 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz);
2536 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT;
2537 }
2538 thread_unlock(td);
2539
2540 return (pctcpu);
2541 }
2542
2543 /*
2544 * Enforce affinity settings for a thread. Called after adjustments to
2545 * cpumask.
2546 */
2547 void
2548 sched_affinity(struct thread *td)
2549 {
2550 #ifdef SMP
2551 struct td_sched *ts;
2552 int cpu;
2553
2554 THREAD_LOCK_ASSERT(td, MA_OWNED);
2555 ts = td->td_sched;
2556 if (THREAD_CAN_SCHED(td, ts->ts_cpu))
2557 return;
2558 if (TD_ON_RUNQ(td)) {
2559 sched_rem(td);
2560 sched_add(td, SRQ_BORING);
2561 return;
2562 }
2563 if (!TD_IS_RUNNING(td))
2564 return;
2565 td->td_flags |= TDF_NEEDRESCHED;
2566 if (!THREAD_CAN_MIGRATE(td))
2567 return;
2568 /*
2569 * Assign the new cpu and force a switch before returning to
2570 * userspace. If the target thread is not running locally send
2571 * an ipi to force the issue.
2572 */
2573 cpu = ts->ts_cpu;
2574 ts->ts_cpu = sched_pickcpu(td, 0);
2575 if (cpu != PCPU_GET(cpuid))
2576 ipi_selected(1 << cpu, IPI_PREEMPT);
2577 #endif
2578 }
2579
2580 /*
2581 * Bind a thread to a target cpu.
2582 */
2583 void
2584 sched_bind(struct thread *td, int cpu)
2585 {
2586 struct td_sched *ts;
2587
2588 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
2589 ts = td->td_sched;
2590 if (ts->ts_flags & TSF_BOUND)
2591 sched_unbind(td);
2592 ts->ts_flags |= TSF_BOUND;
2593 #ifdef SMP
2594 sched_pin();
2595 if (PCPU_GET(cpuid) == cpu)
2596 return;
2597 ts->ts_cpu = cpu;
2598 /* When we return from mi_switch we'll be on the correct cpu. */
2599 mi_switch(SW_VOL, NULL);
2600 #endif
2601 }
2602
2603 /*
2604 * Release a bound thread.
2605 */
2606 void
2607 sched_unbind(struct thread *td)
2608 {
2609 struct td_sched *ts;
2610
2611 THREAD_LOCK_ASSERT(td, MA_OWNED);
2612 ts = td->td_sched;
2613 if ((ts->ts_flags & TSF_BOUND) == 0)
2614 return;
2615 ts->ts_flags &= ~TSF_BOUND;
2616 #ifdef SMP
2617 sched_unpin();
2618 #endif
2619 }
2620
2621 int
2622 sched_is_bound(struct thread *td)
2623 {
2624 THREAD_LOCK_ASSERT(td, MA_OWNED);
2625 return (td->td_sched->ts_flags & TSF_BOUND);
2626 }
2627
2628 /*
2629 * Basic yield call.
2630 */
2631 void
2632 sched_relinquish(struct thread *td)
2633 {
2634 thread_lock(td);
2635 SCHED_STAT_INC(switch_relinquish);
2636 mi_switch(SW_VOL, NULL);
2637 thread_unlock(td);
2638 }
2639
2640 /*
2641 * Return the total system load.
2642 */
2643 int
2644 sched_load(void)
2645 {
2646 #ifdef SMP
2647 int total;
2648 int i;
2649
2650 total = 0;
2651 for (i = 0; i <= tdg_maxid; i++)
2652 total += TDQ_GROUP(i)->tdg_load;
2653 return (total);
2654 #else
2655 return (TDQ_SELF()->tdq_sysload);
2656 #endif
2657 }
2658
2659 int
2660 sched_sizeof_proc(void)
2661 {
2662 return (sizeof(struct proc));
2663 }
2664
2665 int
2666 sched_sizeof_thread(void)
2667 {
2668 return (sizeof(struct thread) + sizeof(struct td_sched));
2669 }
2670
2671 /*
2672 * The actual idle process.
2673 */
2674 void
2675 sched_idletd(void *dummy)
2676 {
2677 struct thread *td;
2678 struct tdq *tdq;
2679
2680 td = curthread;
2681 tdq = TDQ_SELF();
2682 mtx_assert(&Giant, MA_NOTOWNED);
2683 /* ULE relies on preemption for idle interruption. */
2684 for (;;) {
2685 #ifdef SMP
2686 if (tdq_idled(tdq))
2687 cpu_idle();
2688 #else
2689 cpu_idle();
2690 #endif
2691 }
2692 }
2693
2694 /*
2695 * A CPU is entering for the first time or a thread is exiting.
2696 */
2697 void
2698 sched_throw(struct thread *td)
2699 {
2700 struct thread *newtd;
2701 struct tdq *tdq;
2702
2703 tdq = TDQ_SELF();
2704 if (td == NULL) {
2705 /* Correct spinlock nesting and acquire the correct lock. */
2706 TDQ_LOCK(tdq);
2707 spinlock_exit();
2708 } else {
2709 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2710 tdq_load_rem(tdq, td->td_sched);
2711 }
2712 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
2713 newtd = choosethread();
2714 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
2715 PCPU_SET(switchtime, cpu_ticks());
2716 PCPU_SET(switchticks, ticks);
2717 cpu_throw(td, newtd); /* doesn't return */
2718 }
2719
2720 /*
2721 * This is called from fork_exit(). Just acquire the correct locks and
2722 * let fork do the rest of the work.
2723 */
2724 void
2725 sched_fork_exit(struct thread *td)
2726 {
2727 struct td_sched *ts;
2728 struct tdq *tdq;
2729 int cpuid;
2730
2731 /*
2732 * Finish setting up thread glue so that it begins execution in a
2733 * non-nested critical section with the scheduler lock held.
2734 */
2735 cpuid = PCPU_GET(cpuid);
2736 tdq = TDQ_CPU(cpuid);
2737 ts = td->td_sched;
2738 if (TD_IS_IDLETHREAD(td))
2739 td->td_lock = TDQ_LOCKPTR(tdq);
2740 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2741 td->td_oncpu = cpuid;
2742 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
2743 }
2744
2745 static SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0,
2746 "Scheduler");
2747 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0,
2748 "Scheduler name");
2749 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
2750 "Slice size for timeshare threads");
2751 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0,
2752 "Interactivity score threshold");
2753 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, &preempt_thresh,
2754 0,"Min priority for preemption, lower priorities have greater precedence");
2755 #ifdef SMP
2756 SYSCTL_INT(_kern_sched, OID_AUTO, pick_pri, CTLFLAG_RW, &pick_pri, 0,
2757 "Pick the target cpu based on priority rather than load.");
2758 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0,
2759 "Number of hz ticks to keep thread affinity for");
2760 SYSCTL_INT(_kern_sched, OID_AUTO, tryself, CTLFLAG_RW, &tryself, 0, "");
2761 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0,
2762 "Enables the long-term load balancer");
2763 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW,
2764 &balance_interval, 0,
2765 "Average frequency in stathz ticks to run the long-term balancer");
2766 SYSCTL_INT(_kern_sched, OID_AUTO, steal_htt, CTLFLAG_RW, &steal_htt, 0,
2767 "Steals work from another hyper-threaded core on idle");
2768 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0,
2769 "Attempts to steal work from other cores before idling");
2770 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0,
2771 "Minimum load on remote cpu before we'll steal");
2772 SYSCTL_INT(_kern_sched, OID_AUTO, topology, CTLFLAG_RD, &topology, 0,
2773 "True when a topology has been specified by the MD code.");
2774 #endif
2775
2776 /* ps compat. All cpu percentages from ULE are weighted. */
2777 static int ccpu = 0;
2778 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
2779
2780
2781 #define KERN_SWITCH_INCLUDE 1
2782 #include "kern/kern_switch.c"
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