2 * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice unmodified, this list of conditions, and the following
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.
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.
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.
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.
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
41 #include "opt_hwpmc_hooks.h"
42 #include "opt_sched.h"
44 #include <sys/param.h>
45 #include <sys/systm.h>
47 #include <sys/kernel.h>
50 #include <sys/mutex.h>
52 #include <sys/resource.h>
53 #include <sys/resourcevar.h>
54 #include <sys/sched.h>
58 #include <sys/sysctl.h>
59 #include <sys/sysproto.h>
60 #include <sys/turnstile.h>
62 #include <sys/vmmeter.h>
63 #include <sys/cpuset.h>
67 #include <sys/pmckern.h>
71 #include <sys/dtrace_bsd.h>
72 int dtrace_vtime_active;
73 dtrace_vtime_switch_func_t dtrace_vtime_switch_func;
76 #include <machine/cpu.h>
77 #include <machine/smp.h>
81 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX)))
82 #define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU)))
83 #define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load"))
86 * Thread scheduler specific section. All fields are protected
90 struct runq *ts_runq; /* Run-queue we're queued on. */
91 short ts_flags; /* TSF_* flags. */
92 u_char ts_cpu; /* CPU that we have affinity for. */
93 int ts_rltick; /* Real last tick, for affinity. */
94 int ts_slice; /* Ticks of slice remaining. */
95 u_int ts_slptime; /* Number of ticks we vol. slept */
96 u_int ts_runtime; /* Number of ticks we were running */
97 int ts_ltick; /* Last tick that we were running on */
98 int ts_ftick; /* First tick that we were running on */
99 int ts_ticks; /* Tick count */
101 char ts_name[TS_NAME_LEN];
104 /* flags kept in ts_flags */
105 #define TSF_BOUND 0x0001 /* Thread can not migrate. */
106 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */
108 static struct td_sched td_sched0;
110 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0)
111 #define THREAD_CAN_SCHED(td, cpu) \
112 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask)
115 * Priority ranges used for interactive and non-interactive timeshare
116 * threads. The timeshare priorities are split up into four ranges.
117 * The first range handles interactive threads. The last three ranges
118 * (NHALF, x, and NHALF) handle non-interactive threads with the outer
119 * ranges supporting nice values.
121 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1)
122 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2)
123 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE)
125 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE
126 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1)
127 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE)
128 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE
131 * Cpu percentage computation macros and defines.
133 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across.
134 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across.
135 * SCHED_TICK_MAX: Maximum number of ticks before scaling back.
136 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results.
137 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count.
138 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks.
140 #define SCHED_TICK_SECS 10
141 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS)
142 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz)
143 #define SCHED_TICK_SHIFT 10
144 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT)
145 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz))
148 * These macros determine priorities for non-interactive threads. They are
149 * assigned a priority based on their recent cpu utilization as expressed
150 * by the ratio of ticks to the tick total. NHALF priorities at the start
151 * and end of the MIN to MAX timeshare range are only reachable with negative
152 * or positive nice respectively.
154 * PRI_RANGE: Priority range for utilization dependent priorities.
155 * PRI_NRESV: Number of nice values.
156 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total.
157 * PRI_NICE: Determines the part of the priority inherited from nice.
159 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN)
160 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2)
161 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF)
162 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF)
163 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1)
164 #define SCHED_PRI_TICKS(ts) \
165 (SCHED_TICK_HZ((ts)) / \
166 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE))
167 #define SCHED_PRI_NICE(nice) (nice)
170 * These determine the interactivity of a process. Interactivity differs from
171 * cpu utilization in that it expresses the voluntary time slept vs time ran
172 * while cpu utilization includes all time not running. This more accurately
173 * models the intent of the thread.
175 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate
176 * before throttling back.
177 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time.
178 * INTERACT_MAX: Maximum interactivity value. Smaller is better.
179 * INTERACT_THRESH: Threshold for placement on the current runq.
181 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT)
182 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT)
183 #define SCHED_INTERACT_MAX (100)
184 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2)
185 #define SCHED_INTERACT_THRESH (30)
188 * These parameters determine the slice behavior for batch work.
190 #define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */
191 #define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */
193 /* Flags kept in td_flags. */
194 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */
197 * tickincr: Converts a stathz tick into a hz domain scaled by
198 * the shift factor. Without the shift the error rate
199 * due to rounding would be unacceptably high.
200 * realstathz: stathz is sometimes 0 and run off of hz.
201 * sched_slice: Runtime of each thread before rescheduling.
202 * preempt_thresh: Priority threshold for preemption and remote IPIs.
204 static int sched_interact = SCHED_INTERACT_THRESH;
205 static int tickincr = 8 << SCHED_TICK_SHIFT;
206 static int realstathz = 127; /* reset during boot. */
207 static int sched_slice = 10; /* reset during boot. */
208 static int sched_slice_min = 1; /* reset during boot. */
210 #ifdef FULL_PREEMPTION
211 static int preempt_thresh = PRI_MAX_IDLE;
213 static int preempt_thresh = PRI_MIN_KERN;
216 static int preempt_thresh = 0;
218 static int static_boost = PRI_MIN_BATCH;
219 static int sched_idlespins = 10000;
220 static int sched_idlespinthresh = -1;
223 * tdq - per processor runqs and statistics. All fields are protected by the
224 * tdq_lock. The load and lowpri may be accessed without to avoid excess
225 * locking in sched_pickcpu();
229 * Ordered to improve efficiency of cpu_search() and switch().
230 * tdq_lock is padded to avoid false sharing with tdq_load and
233 struct mtx_padalign tdq_lock; /* run queue lock. */
234 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */
235 volatile int tdq_load; /* Aggregate load. */
236 volatile int tdq_cpu_idle; /* cpu_idle() is active. */
237 int tdq_sysload; /* For loadavg, !ITHD load. */
238 int tdq_transferable; /* Transferable thread count. */
239 short tdq_switchcnt; /* Switches this tick. */
240 short tdq_oldswitchcnt; /* Switches last tick. */
241 u_char tdq_lowpri; /* Lowest priority thread. */
242 u_char tdq_ipipending; /* IPI pending. */
243 u_char tdq_idx; /* Current insert index. */
244 u_char tdq_ridx; /* Current removal index. */
245 struct runq tdq_realtime; /* real-time run queue. */
246 struct runq tdq_timeshare; /* timeshare run queue. */
247 struct runq tdq_idle; /* Queue of IDLE threads. */
248 char tdq_name[TDQ_NAME_LEN];
250 char tdq_loadname[TDQ_LOADNAME_LEN];
254 /* Idle thread states and config. */
255 #define TDQ_RUNNING 1
259 struct cpu_group *cpu_top; /* CPU topology */
261 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000))
262 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity))
267 static int rebalance = 1;
268 static int balance_interval = 128; /* Default set in sched_initticks(). */
270 static int steal_idle = 1;
271 static int steal_thresh = 2;
274 * One thread queue per processor.
276 static struct tdq tdq_cpu[MAXCPU];
277 static struct tdq *balance_tdq;
278 static int balance_ticks;
279 static DPCPU_DEFINE(uint32_t, randomval);
281 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)])
282 #define TDQ_CPU(x) (&tdq_cpu[(x)])
283 #define TDQ_ID(x) ((int)((x) - tdq_cpu))
285 static struct tdq tdq_cpu;
287 #define TDQ_ID(x) (0)
288 #define TDQ_SELF() (&tdq_cpu)
289 #define TDQ_CPU(x) (&tdq_cpu)
292 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type))
293 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t)))
294 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f))
295 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t)))
296 #define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock))
298 static void sched_priority(struct thread *);
299 static void sched_thread_priority(struct thread *, u_char);
300 static int sched_interact_score(struct thread *);
301 static void sched_interact_update(struct thread *);
302 static void sched_interact_fork(struct thread *);
303 static void sched_pctcpu_update(struct td_sched *, int);
305 /* Operations on per processor queues */
306 static struct thread *tdq_choose(struct tdq *);
307 static void tdq_setup(struct tdq *);
308 static void tdq_load_add(struct tdq *, struct thread *);
309 static void tdq_load_rem(struct tdq *, struct thread *);
310 static __inline void tdq_runq_add(struct tdq *, struct thread *, int);
311 static __inline void tdq_runq_rem(struct tdq *, struct thread *);
312 static inline int sched_shouldpreempt(int, int, int);
313 void tdq_print(int cpu);
314 static void runq_print(struct runq *rq);
315 static void tdq_add(struct tdq *, struct thread *, int);
317 static int tdq_move(struct tdq *, struct tdq *);
318 static int tdq_idled(struct tdq *);
319 static void tdq_notify(struct tdq *, struct thread *);
320 static struct thread *tdq_steal(struct tdq *, int);
321 static struct thread *runq_steal(struct runq *, int);
322 static int sched_pickcpu(struct thread *, int);
323 static void sched_balance(void);
324 static int sched_balance_pair(struct tdq *, struct tdq *);
325 static inline struct tdq *sched_setcpu(struct thread *, int, int);
326 static inline void thread_unblock_switch(struct thread *, struct mtx *);
327 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int);
328 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS);
329 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb,
330 struct cpu_group *cg, int indent);
333 static void sched_setup(void *dummy);
334 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL);
336 static void sched_initticks(void *dummy);
337 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks,
340 SDT_PROVIDER_DEFINE(sched);
342 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *",
343 "struct proc *", "uint8_t");
344 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *",
345 "struct proc *", "void *");
346 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *",
347 "struct proc *", "void *", "int");
348 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *",
349 "struct proc *", "uint8_t", "struct thread *");
350 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int");
351 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *",
353 SDT_PROBE_DEFINE(sched, , , on__cpu);
354 SDT_PROBE_DEFINE(sched, , , remain__cpu);
355 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *",
359 * Print the threads waiting on a run-queue.
362 runq_print(struct runq *rq)
370 for (i = 0; i < RQB_LEN; i++) {
371 printf("\t\trunq bits %d 0x%zx\n",
372 i, rq->rq_status.rqb_bits[i]);
373 for (j = 0; j < RQB_BPW; j++)
374 if (rq->rq_status.rqb_bits[i] & (1ul << j)) {
375 pri = j + (i << RQB_L2BPW);
376 rqh = &rq->rq_queues[pri];
377 TAILQ_FOREACH(td, rqh, td_runq) {
378 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n",
379 td, td->td_name, td->td_priority,
380 td->td_rqindex, pri);
387 * Print the status of a per-cpu thread queue. Should be a ddb show cmd.
396 printf("tdq %d:\n", TDQ_ID(tdq));
397 printf("\tlock %p\n", TDQ_LOCKPTR(tdq));
398 printf("\tLock name: %s\n", tdq->tdq_name);
399 printf("\tload: %d\n", tdq->tdq_load);
400 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt);
401 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt);
402 printf("\ttimeshare idx: %d\n", tdq->tdq_idx);
403 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx);
404 printf("\tload transferable: %d\n", tdq->tdq_transferable);
405 printf("\tlowest priority: %d\n", tdq->tdq_lowpri);
406 printf("\trealtime runq:\n");
407 runq_print(&tdq->tdq_realtime);
408 printf("\ttimeshare runq:\n");
409 runq_print(&tdq->tdq_timeshare);
410 printf("\tidle runq:\n");
411 runq_print(&tdq->tdq_idle);
415 sched_shouldpreempt(int pri, int cpri, int remote)
418 * If the new priority is not better than the current priority there is
424 * Always preempt idle.
426 if (cpri >= PRI_MIN_IDLE)
429 * If preemption is disabled don't preempt others.
431 if (preempt_thresh == 0)
434 * Preempt if we exceed the threshold.
436 if (pri <= preempt_thresh)
439 * If we're interactive or better and there is non-interactive
440 * or worse running preempt only remote processors.
442 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT)
448 * Add a thread to the actual run-queue. Keeps transferable counts up to
449 * date with what is actually on the run-queue. Selects the correct
450 * queue position for timeshare threads.
453 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags)
458 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
459 THREAD_LOCK_ASSERT(td, MA_OWNED);
461 pri = td->td_priority;
464 if (THREAD_CAN_MIGRATE(td)) {
465 tdq->tdq_transferable++;
466 ts->ts_flags |= TSF_XFERABLE;
468 if (pri < PRI_MIN_BATCH) {
469 ts->ts_runq = &tdq->tdq_realtime;
470 } else if (pri <= PRI_MAX_BATCH) {
471 ts->ts_runq = &tdq->tdq_timeshare;
472 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH,
473 ("Invalid priority %d on timeshare runq", pri));
475 * This queue contains only priorities between MIN and MAX
476 * realtime. Use the whole queue to represent these values.
478 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) {
479 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE;
480 pri = (pri + tdq->tdq_idx) % RQ_NQS;
482 * This effectively shortens the queue by one so we
483 * can have a one slot difference between idx and
484 * ridx while we wait for threads to drain.
486 if (tdq->tdq_ridx != tdq->tdq_idx &&
487 pri == tdq->tdq_ridx)
488 pri = (unsigned char)(pri - 1) % RQ_NQS;
491 runq_add_pri(ts->ts_runq, td, pri, flags);
494 ts->ts_runq = &tdq->tdq_idle;
495 runq_add(ts->ts_runq, td, flags);
499 * Remove a thread from a run-queue. This typically happens when a thread
500 * is selected to run. Running threads are not on the queue and the
501 * transferable count does not reflect them.
504 tdq_runq_rem(struct tdq *tdq, struct thread *td)
509 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
510 KASSERT(ts->ts_runq != NULL,
511 ("tdq_runq_remove: thread %p null ts_runq", td));
512 if (ts->ts_flags & TSF_XFERABLE) {
513 tdq->tdq_transferable--;
514 ts->ts_flags &= ~TSF_XFERABLE;
516 if (ts->ts_runq == &tdq->tdq_timeshare) {
517 if (tdq->tdq_idx != tdq->tdq_ridx)
518 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx);
520 runq_remove_idx(ts->ts_runq, td, NULL);
522 runq_remove(ts->ts_runq, td);
526 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load
527 * for this thread to the referenced thread queue.
530 tdq_load_add(struct tdq *tdq, struct thread *td)
533 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
534 THREAD_LOCK_ASSERT(td, MA_OWNED);
537 if ((td->td_flags & TDF_NOLOAD) == 0)
539 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load);
540 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load);
544 * Remove the load from a thread that is transitioning to a sleep state or
548 tdq_load_rem(struct tdq *tdq, struct thread *td)
551 THREAD_LOCK_ASSERT(td, MA_OWNED);
552 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
553 KASSERT(tdq->tdq_load != 0,
554 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq)));
557 if ((td->td_flags & TDF_NOLOAD) == 0)
559 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load);
560 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load);
564 * Bound timeshare latency by decreasing slice size as load increases. We
565 * consider the maximum latency as the sum of the threads waiting to run
566 * aside from curthread and target no more than sched_slice latency but
567 * no less than sched_slice_min runtime.
570 tdq_slice(struct tdq *tdq)
575 * It is safe to use sys_load here because this is called from
576 * contexts where timeshare threads are running and so there
577 * cannot be higher priority load in the system.
579 load = tdq->tdq_sysload - 1;
580 if (load >= SCHED_SLICE_MIN_DIVISOR)
581 return (sched_slice_min);
583 return (sched_slice);
584 return (sched_slice / load);
588 * Set lowpri to its exact value by searching the run-queue and
589 * evaluating curthread. curthread may be passed as an optimization.
592 tdq_setlowpri(struct tdq *tdq, struct thread *ctd)
596 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
598 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread;
599 td = tdq_choose(tdq);
600 if (td == NULL || td->td_priority > ctd->td_priority)
601 tdq->tdq_lowpri = ctd->td_priority;
603 tdq->tdq_lowpri = td->td_priority;
610 int cs_pri; /* Min priority for low. */
611 int cs_limit; /* Max load for low, min load for high. */
616 #define CPU_SEARCH_LOWEST 0x1
617 #define CPU_SEARCH_HIGHEST 0x2
618 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST)
620 #define CPUSET_FOREACH(cpu, mask) \
621 for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \
622 if (CPU_ISSET(cpu, &mask))
624 static __inline int cpu_search(const struct cpu_group *cg, struct cpu_search *low,
625 struct cpu_search *high, const int match);
626 int cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low);
627 int cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high);
628 int cpu_search_both(const struct cpu_group *cg, struct cpu_search *low,
629 struct cpu_search *high);
632 * Search the tree of cpu_groups for the lowest or highest loaded cpu
633 * according to the match argument. This routine actually compares the
634 * load on all paths through the tree and finds the least loaded cpu on
635 * the least loaded path, which may differ from the least loaded cpu in
636 * the system. This balances work among caches and busses.
638 * This inline is instantiated in three forms below using constants for the
639 * match argument. It is reduced to the minimum set for each case. It is
640 * also recursive to the depth of the tree.
643 cpu_search(const struct cpu_group *cg, struct cpu_search *low,
644 struct cpu_search *high, const int match)
646 struct cpu_search lgroup;
647 struct cpu_search hgroup;
649 struct cpu_group *child;
651 int cpu, i, hload, lload, load, total, rnd, *rndptr;
654 cpumask = cg->cg_mask;
655 if (match & CPU_SEARCH_LOWEST) {
659 if (match & CPU_SEARCH_HIGHEST) {
664 /* Iterate through the child CPU groups and then remaining CPUs. */
665 for (i = cg->cg_children, cpu = mp_maxid; ; ) {
667 #ifdef HAVE_INLINE_FFSL
668 cpu = CPU_FFS(&cpumask) - 1;
670 while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask))
677 child = &cg->cg_child[i - 1];
679 if (match & CPU_SEARCH_LOWEST)
681 if (match & CPU_SEARCH_HIGHEST)
683 if (child) { /* Handle child CPU group. */
684 CPU_NAND(&cpumask, &child->cg_mask);
686 case CPU_SEARCH_LOWEST:
687 load = cpu_search_lowest(child, &lgroup);
689 case CPU_SEARCH_HIGHEST:
690 load = cpu_search_highest(child, &hgroup);
692 case CPU_SEARCH_BOTH:
693 load = cpu_search_both(child, &lgroup, &hgroup);
696 } else { /* Handle child CPU. */
697 CPU_CLR(cpu, &cpumask);
699 load = tdq->tdq_load * 256;
700 rndptr = DPCPU_PTR(randomval);
701 rnd = (*rndptr = *rndptr * 69069 + 5) >> 26;
702 if (match & CPU_SEARCH_LOWEST) {
703 if (cpu == low->cs_prefer)
705 /* If that CPU is allowed and get data. */
706 if (tdq->tdq_lowpri > lgroup.cs_pri &&
707 tdq->tdq_load <= lgroup.cs_limit &&
708 CPU_ISSET(cpu, &lgroup.cs_mask)) {
710 lgroup.cs_load = load - rnd;
713 if (match & CPU_SEARCH_HIGHEST)
714 if (tdq->tdq_load >= hgroup.cs_limit &&
715 tdq->tdq_transferable &&
716 CPU_ISSET(cpu, &hgroup.cs_mask)) {
718 hgroup.cs_load = load - rnd;
723 /* We have info about child item. Compare it. */
724 if (match & CPU_SEARCH_LOWEST) {
725 if (lgroup.cs_cpu >= 0 &&
727 (load == lload && lgroup.cs_load < low->cs_load))) {
729 low->cs_cpu = lgroup.cs_cpu;
730 low->cs_load = lgroup.cs_load;
733 if (match & CPU_SEARCH_HIGHEST)
734 if (hgroup.cs_cpu >= 0 &&
736 (load == hload && hgroup.cs_load > high->cs_load))) {
738 high->cs_cpu = hgroup.cs_cpu;
739 high->cs_load = hgroup.cs_load;
743 if (i == 0 && CPU_EMPTY(&cpumask))
746 #ifndef HAVE_INLINE_FFSL
755 * cpu_search instantiations must pass constants to maintain the inline
759 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low)
761 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST);
765 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high)
767 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST);
771 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low,
772 struct cpu_search *high)
774 return cpu_search(cg, low, high, CPU_SEARCH_BOTH);
778 * Find the cpu with the least load via the least loaded path that has a
779 * lowpri greater than pri pri. A pri of -1 indicates any priority is
783 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload,
786 struct cpu_search low;
789 low.cs_prefer = prefer;
792 low.cs_limit = maxload;
793 cpu_search_lowest(cg, &low);
798 * Find the cpu with the highest load via the highest loaded path.
801 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload)
803 struct cpu_search high;
807 high.cs_limit = minload;
808 cpu_search_highest(cg, &high);
813 sched_balance_group(struct cpu_group *cg)
815 cpuset_t hmask, lmask;
816 int high, low, anylow;
820 high = sched_highest(cg, hmask, 1);
821 /* Stop if there is no more CPU with transferrable threads. */
824 CPU_CLR(high, &hmask);
825 CPU_COPY(&hmask, &lmask);
826 /* Stop if there is no more CPU left for low. */
827 if (CPU_EMPTY(&lmask))
831 low = sched_lowest(cg, lmask, -1,
832 TDQ_CPU(high)->tdq_load - 1, high);
833 /* Stop if we looked well and found no less loaded CPU. */
834 if (anylow && low == -1)
836 /* Go to next high if we found no less loaded CPU. */
839 /* Transfer thread from high to low. */
840 if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) {
841 /* CPU that got thread can no longer be a donor. */
842 CPU_CLR(low, &hmask);
845 * If failed, then there is no threads on high
846 * that can run on this low. Drop low from low
847 * mask and look for different one.
849 CPU_CLR(low, &lmask);
862 * Select a random time between .5 * balance_interval and
863 * 1.5 * balance_interval.
865 balance_ticks = max(balance_interval / 2, 1);
866 balance_ticks += random() % balance_interval;
867 if (smp_started == 0 || rebalance == 0)
871 sched_balance_group(cpu_top);
876 * Lock two thread queues using their address to maintain lock order.
879 tdq_lock_pair(struct tdq *one, struct tdq *two)
883 TDQ_LOCK_FLAGS(two, MTX_DUPOK);
886 TDQ_LOCK_FLAGS(one, MTX_DUPOK);
891 * Unlock two thread queues. Order is not important here.
894 tdq_unlock_pair(struct tdq *one, struct tdq *two)
901 * Transfer load between two imbalanced thread queues.
904 sched_balance_pair(struct tdq *high, struct tdq *low)
909 tdq_lock_pair(high, low);
912 * Determine what the imbalance is and then adjust that to how many
913 * threads we actually have to give up (transferable).
915 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load &&
916 (moved = tdq_move(high, low)) > 0) {
918 * In case the target isn't the current cpu IPI it to force a
919 * reschedule with the new workload.
922 if (cpu != PCPU_GET(cpuid))
923 ipi_cpu(cpu, IPI_PREEMPT);
925 tdq_unlock_pair(high, low);
930 * Move a thread from one thread queue to another.
933 tdq_move(struct tdq *from, struct tdq *to)
940 TDQ_LOCK_ASSERT(from, MA_OWNED);
941 TDQ_LOCK_ASSERT(to, MA_OWNED);
945 td = tdq_steal(tdq, cpu);
950 * Although the run queue is locked the thread may be blocked. Lock
951 * it to clear this and acquire the run-queue lock.
954 /* Drop recursive lock on from acquired via thread_lock(). */
958 td->td_lock = TDQ_LOCKPTR(to);
959 tdq_add(to, td, SRQ_YIELDING);
964 * This tdq has idled. Try to steal a thread from another cpu and switch
968 tdq_idled(struct tdq *tdq)
970 struct cpu_group *cg;
976 if (smp_started == 0 || steal_idle == 0)
979 CPU_CLR(PCPU_GET(cpuid), &mask);
980 /* We don't want to be preempted while we're iterating. */
982 for (cg = tdq->tdq_cg; cg != NULL; ) {
983 if ((cg->cg_flags & CG_FLAG_THREAD) == 0)
984 thresh = steal_thresh;
987 cpu = sched_highest(cg, mask, thresh);
992 steal = TDQ_CPU(cpu);
994 tdq_lock_pair(tdq, steal);
995 if (steal->tdq_load < thresh || steal->tdq_transferable == 0) {
996 tdq_unlock_pair(tdq, steal);
1000 * If a thread was added while interrupts were disabled don't
1001 * steal one here. If we fail to acquire one due to affinity
1002 * restrictions loop again with this cpu removed from the
1005 if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) {
1006 tdq_unlock_pair(tdq, steal);
1011 mi_switch(SW_VOL | SWT_IDLE, NULL);
1012 thread_unlock(curthread);
1021 * Notify a remote cpu of new work. Sends an IPI if criteria are met.
1024 tdq_notify(struct tdq *tdq, struct thread *td)
1030 if (tdq->tdq_ipipending)
1032 cpu = td->td_sched->ts_cpu;
1033 pri = td->td_priority;
1034 ctd = pcpu_find(cpu)->pc_curthread;
1035 if (!sched_shouldpreempt(pri, ctd->td_priority, 1))
1037 if (TD_IS_IDLETHREAD(ctd)) {
1039 * If the MD code has an idle wakeup routine try that before
1040 * falling back to IPI.
1042 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu))
1045 tdq->tdq_ipipending = 1;
1046 ipi_cpu(cpu, IPI_PREEMPT);
1050 * Steals load from a timeshare queue. Honors the rotating queue head
1053 static struct thread *
1054 runq_steal_from(struct runq *rq, int cpu, u_char start)
1058 struct thread *td, *first;
1063 rqb = &rq->rq_status;
1064 bit = start & (RQB_BPW -1);
1068 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) {
1069 if (rqb->rqb_bits[i] == 0)
1072 for (pri = bit; pri < RQB_BPW; pri++)
1073 if (rqb->rqb_bits[i] & (1ul << pri))
1078 pri = RQB_FFS(rqb->rqb_bits[i]);
1079 pri += (i << RQB_L2BPW);
1080 rqh = &rq->rq_queues[pri];
1081 TAILQ_FOREACH(td, rqh, td_runq) {
1082 if (first && THREAD_CAN_MIGRATE(td) &&
1083 THREAD_CAN_SCHED(td, cpu))
1093 if (first && THREAD_CAN_MIGRATE(first) &&
1094 THREAD_CAN_SCHED(first, cpu))
1100 * Steals load from a standard linear queue.
1102 static struct thread *
1103 runq_steal(struct runq *rq, int cpu)
1111 rqb = &rq->rq_status;
1112 for (word = 0; word < RQB_LEN; word++) {
1113 if (rqb->rqb_bits[word] == 0)
1115 for (bit = 0; bit < RQB_BPW; bit++) {
1116 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0)
1118 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)];
1119 TAILQ_FOREACH(td, rqh, td_runq)
1120 if (THREAD_CAN_MIGRATE(td) &&
1121 THREAD_CAN_SCHED(td, cpu))
1129 * Attempt to steal a thread in priority order from a thread queue.
1131 static struct thread *
1132 tdq_steal(struct tdq *tdq, int cpu)
1136 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
1137 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL)
1139 if ((td = runq_steal_from(&tdq->tdq_timeshare,
1140 cpu, tdq->tdq_ridx)) != NULL)
1142 return (runq_steal(&tdq->tdq_idle, cpu));
1146 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the
1147 * current lock and returns with the assigned queue locked.
1149 static inline struct tdq *
1150 sched_setcpu(struct thread *td, int cpu, int flags)
1155 THREAD_LOCK_ASSERT(td, MA_OWNED);
1157 td->td_sched->ts_cpu = cpu;
1159 * If the lock matches just return the queue.
1161 if (td->td_lock == TDQ_LOCKPTR(tdq))
1165 * If the thread isn't running its lockptr is a
1166 * turnstile or a sleepqueue. We can just lock_set without
1169 if (TD_CAN_RUN(td)) {
1171 thread_lock_set(td, TDQ_LOCKPTR(tdq));
1176 * The hard case, migration, we need to block the thread first to
1177 * prevent order reversals with other cpus locks.
1180 thread_lock_block(td);
1182 thread_lock_unblock(td, TDQ_LOCKPTR(tdq));
1187 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding");
1188 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity");
1189 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity");
1190 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load");
1191 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu");
1192 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration");
1195 sched_pickcpu(struct thread *td, int flags)
1197 struct cpu_group *cg, *ccg;
1198 struct td_sched *ts;
1203 self = PCPU_GET(cpuid);
1205 if (smp_started == 0)
1208 * Don't migrate a running thread from sched_switch().
1210 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td))
1211 return (ts->ts_cpu);
1213 * Prefer to run interrupt threads on the processors that generate
1216 pri = td->td_priority;
1217 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) &&
1218 curthread->td_intr_nesting_level && ts->ts_cpu != self) {
1219 SCHED_STAT_INC(pickcpu_intrbind);
1221 if (TDQ_CPU(self)->tdq_lowpri > pri) {
1222 SCHED_STAT_INC(pickcpu_affinity);
1223 return (ts->ts_cpu);
1227 * If the thread can run on the last cpu and the affinity has not
1228 * expired or it is idle run it there.
1230 tdq = TDQ_CPU(ts->ts_cpu);
1232 if (THREAD_CAN_SCHED(td, ts->ts_cpu) &&
1233 tdq->tdq_lowpri >= PRI_MIN_IDLE &&
1234 SCHED_AFFINITY(ts, CG_SHARE_L2)) {
1235 if (cg->cg_flags & CG_FLAG_THREAD) {
1236 CPUSET_FOREACH(cpu, cg->cg_mask) {
1237 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE)
1242 if (cpu > mp_maxid) {
1243 SCHED_STAT_INC(pickcpu_idle_affinity);
1244 return (ts->ts_cpu);
1248 * Search for the last level cache CPU group in the tree.
1249 * Skip caches with expired affinity time and SMT groups.
1250 * Affinity to higher level caches will be handled less aggressively.
1252 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) {
1253 if (cg->cg_flags & CG_FLAG_THREAD)
1255 if (!SCHED_AFFINITY(ts, cg->cg_level))
1262 /* Search the group for the less loaded idle CPU we can run now. */
1263 mask = td->td_cpuset->cs_mask;
1264 if (cg != NULL && cg != cpu_top &&
1265 CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0)
1266 cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE),
1267 INT_MAX, ts->ts_cpu);
1268 /* Search globally for the less loaded CPU we can run now. */
1270 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu);
1271 /* Search globally for the less loaded CPU. */
1273 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu);
1274 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu."));
1276 * Compare the lowest loaded cpu to current cpu.
1278 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri &&
1279 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE &&
1280 TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) {
1281 SCHED_STAT_INC(pickcpu_local);
1284 SCHED_STAT_INC(pickcpu_lowest);
1285 if (cpu != ts->ts_cpu)
1286 SCHED_STAT_INC(pickcpu_migration);
1292 * Pick the highest priority task we have and return it.
1294 static struct thread *
1295 tdq_choose(struct tdq *tdq)
1299 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
1300 td = runq_choose(&tdq->tdq_realtime);
1303 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx);
1305 KASSERT(td->td_priority >= PRI_MIN_BATCH,
1306 ("tdq_choose: Invalid priority on timeshare queue %d",
1310 td = runq_choose(&tdq->tdq_idle);
1312 KASSERT(td->td_priority >= PRI_MIN_IDLE,
1313 ("tdq_choose: Invalid priority on idle queue %d",
1322 * Initialize a thread queue.
1325 tdq_setup(struct tdq *tdq)
1329 printf("ULE: setup cpu %d\n", TDQ_ID(tdq));
1330 runq_init(&tdq->tdq_realtime);
1331 runq_init(&tdq->tdq_timeshare);
1332 runq_init(&tdq->tdq_idle);
1333 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name),
1334 "sched lock %d", (int)TDQ_ID(tdq));
1335 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock",
1336 MTX_SPIN | MTX_RECURSE);
1338 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname),
1339 "CPU %d load", (int)TDQ_ID(tdq));
1345 sched_setup_smp(void)
1350 cpu_top = smp_topo();
1354 tdq->tdq_cg = smp_topo_find(cpu_top, i);
1355 if (tdq->tdq_cg == NULL)
1356 panic("Can't find cpu group for %d\n", i);
1358 balance_tdq = TDQ_SELF();
1364 * Setup the thread queues and initialize the topology based on MD
1368 sched_setup(void *dummy)
1379 /* Add thread0's load since it's running. */
1381 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF());
1382 tdq_load_add(tdq, &thread0);
1383 tdq->tdq_lowpri = thread0.td_priority;
1388 * This routine determines time constants after stathz and hz are setup.
1392 sched_initticks(void *dummy)
1396 realstathz = stathz ? stathz : hz;
1397 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR;
1398 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR;
1399 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
1403 * tickincr is shifted out by 10 to avoid rounding errors due to
1404 * hz not being evenly divisible by stathz on all platforms.
1406 incr = (hz << SCHED_TICK_SHIFT) / realstathz;
1408 * This does not work for values of stathz that are more than
1409 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen.
1416 * Set the default balance interval now that we know
1417 * what realstathz is.
1419 balance_interval = realstathz;
1420 affinity = SCHED_AFFINITY_DEFAULT;
1422 if (sched_idlespinthresh < 0)
1423 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz;
1428 * This is the core of the interactivity algorithm. Determines a score based
1429 * on past behavior. It is the ratio of sleep time to run time scaled to
1430 * a [0, 100] integer. This is the voluntary sleep time of a process, which
1431 * differs from the cpu usage because it does not account for time spent
1432 * waiting on a run-queue. Would be prettier if we had floating point.
1435 sched_interact_score(struct thread *td)
1437 struct td_sched *ts;
1442 * The score is only needed if this is likely to be an interactive
1443 * task. Don't go through the expense of computing it if there's
1446 if (sched_interact <= SCHED_INTERACT_HALF &&
1447 ts->ts_runtime >= ts->ts_slptime)
1448 return (SCHED_INTERACT_HALF);
1450 if (ts->ts_runtime > ts->ts_slptime) {
1451 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF);
1452 return (SCHED_INTERACT_HALF +
1453 (SCHED_INTERACT_HALF - (ts->ts_slptime / div)));
1455 if (ts->ts_slptime > ts->ts_runtime) {
1456 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF);
1457 return (ts->ts_runtime / div);
1459 /* runtime == slptime */
1461 return (SCHED_INTERACT_HALF);
1464 * This can happen if slptime and runtime are 0.
1471 * Scale the scheduling priority according to the "interactivity" of this
1475 sched_priority(struct thread *td)
1480 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
1483 * If the score is interactive we place the thread in the realtime
1484 * queue with a priority that is less than kernel and interrupt
1485 * priorities. These threads are not subject to nice restrictions.
1487 * Scores greater than this are placed on the normal timeshare queue
1488 * where the priority is partially decided by the most recent cpu
1489 * utilization and the rest is decided by nice value.
1491 * The nice value of the process has a linear effect on the calculated
1492 * score. Negative nice values make it easier for a thread to be
1493 * considered interactive.
1495 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice);
1496 if (score < sched_interact) {
1497 pri = PRI_MIN_INTERACT;
1498 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) /
1499 sched_interact) * score;
1500 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT,
1501 ("sched_priority: invalid interactive priority %d score %d",
1504 pri = SCHED_PRI_MIN;
1505 if (td->td_sched->ts_ticks)
1506 pri += min(SCHED_PRI_TICKS(td->td_sched),
1507 SCHED_PRI_RANGE - 1);
1508 pri += SCHED_PRI_NICE(td->td_proc->p_nice);
1509 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH,
1510 ("sched_priority: invalid priority %d: nice %d, "
1511 "ticks %d ftick %d ltick %d tick pri %d",
1512 pri, td->td_proc->p_nice, td->td_sched->ts_ticks,
1513 td->td_sched->ts_ftick, td->td_sched->ts_ltick,
1514 SCHED_PRI_TICKS(td->td_sched)));
1516 sched_user_prio(td, pri);
1522 * This routine enforces a maximum limit on the amount of scheduling history
1523 * kept. It is called after either the slptime or runtime is adjusted. This
1524 * function is ugly due to integer math.
1527 sched_interact_update(struct thread *td)
1529 struct td_sched *ts;
1533 sum = ts->ts_runtime + ts->ts_slptime;
1534 if (sum < SCHED_SLP_RUN_MAX)
1537 * This only happens from two places:
1538 * 1) We have added an unusual amount of run time from fork_exit.
1539 * 2) We have added an unusual amount of sleep time from sched_sleep().
1541 if (sum > SCHED_SLP_RUN_MAX * 2) {
1542 if (ts->ts_runtime > ts->ts_slptime) {
1543 ts->ts_runtime = SCHED_SLP_RUN_MAX;
1546 ts->ts_slptime = SCHED_SLP_RUN_MAX;
1552 * If we have exceeded by more than 1/5th then the algorithm below
1553 * will not bring us back into range. Dividing by two here forces
1554 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX]
1556 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) {
1557 ts->ts_runtime /= 2;
1558 ts->ts_slptime /= 2;
1561 ts->ts_runtime = (ts->ts_runtime / 5) * 4;
1562 ts->ts_slptime = (ts->ts_slptime / 5) * 4;
1566 * Scale back the interactivity history when a child thread is created. The
1567 * history is inherited from the parent but the thread may behave totally
1568 * differently. For example, a shell spawning a compiler process. We want
1569 * to learn that the compiler is behaving badly very quickly.
1572 sched_interact_fork(struct thread *td)
1577 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime;
1578 if (sum > SCHED_SLP_RUN_FORK) {
1579 ratio = sum / SCHED_SLP_RUN_FORK;
1580 td->td_sched->ts_runtime /= ratio;
1581 td->td_sched->ts_slptime /= ratio;
1586 * Called from proc0_init() to setup the scheduler fields.
1593 * Set up the scheduler specific parts of proc0.
1595 proc0.p_sched = NULL; /* XXX */
1596 thread0.td_sched = &td_sched0;
1597 td_sched0.ts_ltick = ticks;
1598 td_sched0.ts_ftick = ticks;
1599 td_sched0.ts_slice = 0;
1603 * This is only somewhat accurate since given many processes of the same
1604 * priority they will switch when their slices run out, which will be
1605 * at most sched_slice stathz ticks.
1608 sched_rr_interval(void)
1611 /* Convert sched_slice from stathz to hz. */
1612 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz));
1616 * Update the percent cpu tracking information when it is requested or
1617 * the total history exceeds the maximum. We keep a sliding history of
1618 * tick counts that slowly decays. This is less precise than the 4BSD
1619 * mechanism since it happens with less regular and frequent events.
1622 sched_pctcpu_update(struct td_sched *ts, int run)
1626 if (t - ts->ts_ltick >= SCHED_TICK_TARG) {
1628 ts->ts_ftick = t - SCHED_TICK_TARG;
1629 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) {
1630 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) *
1631 (ts->ts_ltick - (t - SCHED_TICK_TARG));
1632 ts->ts_ftick = t - SCHED_TICK_TARG;
1635 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT;
1640 * Adjust the priority of a thread. Move it to the appropriate run-queue
1641 * if necessary. This is the back-end for several priority related
1645 sched_thread_priority(struct thread *td, u_char prio)
1647 struct td_sched *ts;
1651 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio",
1652 "prio:%d", td->td_priority, "new prio:%d", prio,
1653 KTR_ATTR_LINKED, sched_tdname(curthread));
1654 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio);
1655 if (td != curthread && prio < td->td_priority) {
1656 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
1657 "lend prio", "prio:%d", td->td_priority, "new prio:%d",
1658 prio, KTR_ATTR_LINKED, sched_tdname(td));
1659 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio,
1663 THREAD_LOCK_ASSERT(td, MA_OWNED);
1664 if (td->td_priority == prio)
1667 * If the priority has been elevated due to priority
1668 * propagation, we may have to move ourselves to a new
1669 * queue. This could be optimized to not re-add in some
1672 if (TD_ON_RUNQ(td) && prio < td->td_priority) {
1674 td->td_priority = prio;
1675 sched_add(td, SRQ_BORROWING);
1679 * If the thread is currently running we may have to adjust the lowpri
1680 * information so other cpus are aware of our current priority.
1682 if (TD_IS_RUNNING(td)) {
1683 tdq = TDQ_CPU(ts->ts_cpu);
1684 oldpri = td->td_priority;
1685 td->td_priority = prio;
1686 if (prio < tdq->tdq_lowpri)
1687 tdq->tdq_lowpri = prio;
1688 else if (tdq->tdq_lowpri == oldpri)
1689 tdq_setlowpri(tdq, td);
1692 td->td_priority = prio;
1696 * Update a thread's priority when it is lent another thread's
1700 sched_lend_prio(struct thread *td, u_char prio)
1703 td->td_flags |= TDF_BORROWING;
1704 sched_thread_priority(td, prio);
1708 * Restore a thread's priority when priority propagation is
1709 * over. The prio argument is the minimum priority the thread
1710 * needs to have to satisfy other possible priority lending
1711 * requests. If the thread's regular priority is less
1712 * important than prio, the thread will keep a priority boost
1716 sched_unlend_prio(struct thread *td, u_char prio)
1720 if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
1721 td->td_base_pri <= PRI_MAX_TIMESHARE)
1722 base_pri = td->td_user_pri;
1724 base_pri = td->td_base_pri;
1725 if (prio >= base_pri) {
1726 td->td_flags &= ~TDF_BORROWING;
1727 sched_thread_priority(td, base_pri);
1729 sched_lend_prio(td, prio);
1733 * Standard entry for setting the priority to an absolute value.
1736 sched_prio(struct thread *td, u_char prio)
1740 /* First, update the base priority. */
1741 td->td_base_pri = prio;
1744 * If the thread is borrowing another thread's priority, don't
1745 * ever lower the priority.
1747 if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
1750 /* Change the real priority. */
1751 oldprio = td->td_priority;
1752 sched_thread_priority(td, prio);
1755 * If the thread is on a turnstile, then let the turnstile update
1758 if (TD_ON_LOCK(td) && oldprio != prio)
1759 turnstile_adjust(td, oldprio);
1763 * Set the base user priority, does not effect current running priority.
1766 sched_user_prio(struct thread *td, u_char prio)
1769 td->td_base_user_pri = prio;
1770 if (td->td_lend_user_pri <= prio)
1772 td->td_user_pri = prio;
1776 sched_lend_user_prio(struct thread *td, u_char prio)
1779 THREAD_LOCK_ASSERT(td, MA_OWNED);
1780 td->td_lend_user_pri = prio;
1781 td->td_user_pri = min(prio, td->td_base_user_pri);
1782 if (td->td_priority > td->td_user_pri)
1783 sched_prio(td, td->td_user_pri);
1784 else if (td->td_priority != td->td_user_pri)
1785 td->td_flags |= TDF_NEEDRESCHED;
1789 * Handle migration from sched_switch(). This happens only for
1793 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags)
1797 tdn = TDQ_CPU(td->td_sched->ts_cpu);
1799 tdq_load_rem(tdq, td);
1801 * Do the lock dance required to avoid LOR. We grab an extra
1802 * spinlock nesting to prevent preemption while we're
1803 * not holding either run-queue lock.
1806 thread_lock_block(td); /* This releases the lock on tdq. */
1809 * Acquire both run-queue locks before placing the thread on the new
1810 * run-queue to avoid deadlocks created by placing a thread with a
1811 * blocked lock on the run-queue of a remote processor. The deadlock
1812 * occurs when a third processor attempts to lock the two queues in
1813 * question while the target processor is spinning with its own
1814 * run-queue lock held while waiting for the blocked lock to clear.
1816 tdq_lock_pair(tdn, tdq);
1817 tdq_add(tdn, td, flags);
1818 tdq_notify(tdn, td);
1822 return (TDQ_LOCKPTR(tdn));
1826 * Variadic version of thread_lock_unblock() that does not assume td_lock
1830 thread_unblock_switch(struct thread *td, struct mtx *mtx)
1832 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock,
1837 * Switch threads. This function has to handle threads coming in while
1838 * blocked for some reason, running, or idle. It also must deal with
1839 * migrating a thread from one queue to another as running threads may
1840 * be assigned elsewhere via binding.
1843 sched_switch(struct thread *td, struct thread *newtd, int flags)
1846 struct td_sched *ts;
1849 int cpuid, preempted;
1851 THREAD_LOCK_ASSERT(td, MA_OWNED);
1852 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument"));
1854 cpuid = PCPU_GET(cpuid);
1855 tdq = TDQ_CPU(cpuid);
1858 sched_pctcpu_update(ts, 1);
1859 ts->ts_rltick = ticks;
1860 td->td_lastcpu = td->td_oncpu;
1861 td->td_oncpu = NOCPU;
1862 preempted = !(td->td_flags & TDF_SLICEEND);
1863 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND);
1864 td->td_owepreempt = 0;
1865 if (!TD_IS_IDLETHREAD(td))
1866 tdq->tdq_switchcnt++;
1868 * The lock pointer in an idle thread should never change. Reset it
1869 * to CAN_RUN as well.
1871 if (TD_IS_IDLETHREAD(td)) {
1872 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1874 } else if (TD_IS_RUNNING(td)) {
1875 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1876 srqflag = preempted ?
1877 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
1878 SRQ_OURSELF|SRQ_YIELDING;
1880 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu))
1881 ts->ts_cpu = sched_pickcpu(td, 0);
1883 if (ts->ts_cpu == cpuid)
1884 tdq_runq_add(tdq, td, srqflag);
1886 KASSERT(THREAD_CAN_MIGRATE(td) ||
1887 (ts->ts_flags & TSF_BOUND) != 0,
1888 ("Thread %p shouldn't migrate", td));
1889 mtx = sched_switch_migrate(tdq, td, srqflag);
1892 /* This thread must be going to sleep. */
1894 mtx = thread_lock_block(td);
1895 tdq_load_rem(tdq, td);
1898 * We enter here with the thread blocked and assigned to the
1899 * appropriate cpu run-queue or sleep-queue and with the current
1900 * thread-queue locked.
1902 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
1903 newtd = choosethread();
1905 * Call the MD code to switch contexts if necessary.
1909 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1910 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
1912 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc);
1913 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object);
1914 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
1915 sched_pctcpu_update(newtd->td_sched, 0);
1917 #ifdef KDTRACE_HOOKS
1919 * If DTrace has set the active vtime enum to anything
1920 * other than INACTIVE (0), then it should have set the
1923 if (dtrace_vtime_active)
1924 (*dtrace_vtime_switch_func)(newtd);
1927 cpu_switch(td, newtd, mtx);
1929 * We may return from cpu_switch on a different cpu. However,
1930 * we always return with td_lock pointing to the current cpu's
1933 cpuid = PCPU_GET(cpuid);
1934 tdq = TDQ_CPU(cpuid);
1935 lock_profile_obtain_lock_success(
1936 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__);
1938 SDT_PROBE0(sched, , , on__cpu);
1940 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1941 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
1944 thread_unblock_switch(td, mtx);
1945 SDT_PROBE0(sched, , , remain__cpu);
1948 * Assert that all went well and return.
1950 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED);
1951 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1952 td->td_oncpu = cpuid;
1956 * Adjust thread priorities as a result of a nice request.
1959 sched_nice(struct proc *p, int nice)
1963 PROC_LOCK_ASSERT(p, MA_OWNED);
1966 FOREACH_THREAD_IN_PROC(p, td) {
1969 sched_prio(td, td->td_base_user_pri);
1975 * Record the sleep time for the interactivity scorer.
1978 sched_sleep(struct thread *td, int prio)
1981 THREAD_LOCK_ASSERT(td, MA_OWNED);
1983 td->td_slptick = ticks;
1984 if (TD_IS_SUSPENDED(td) || prio >= PSOCK)
1985 td->td_flags |= TDF_CANSWAP;
1986 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
1988 if (static_boost == 1 && prio)
1989 sched_prio(td, prio);
1990 else if (static_boost && td->td_priority > static_boost)
1991 sched_prio(td, static_boost);
1995 * Schedule a thread to resume execution and record how long it voluntarily
1996 * slept. We also update the pctcpu, interactivity, and priority.
1999 sched_wakeup(struct thread *td)
2001 struct td_sched *ts;
2004 THREAD_LOCK_ASSERT(td, MA_OWNED);
2006 td->td_flags &= ~TDF_CANSWAP;
2008 * If we slept for more than a tick update our interactivity and
2011 slptick = td->td_slptick;
2013 if (slptick && slptick != ticks) {
2014 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT;
2015 sched_interact_update(td);
2016 sched_pctcpu_update(ts, 0);
2019 * Reset the slice value since we slept and advanced the round-robin.
2022 sched_add(td, SRQ_BORING);
2026 * Penalize the parent for creating a new child and initialize the child's
2030 sched_fork(struct thread *td, struct thread *child)
2032 THREAD_LOCK_ASSERT(td, MA_OWNED);
2033 sched_pctcpu_update(td->td_sched, 1);
2034 sched_fork_thread(td, child);
2036 * Penalize the parent and child for forking.
2038 sched_interact_fork(child);
2039 sched_priority(child);
2040 td->td_sched->ts_runtime += tickincr;
2041 sched_interact_update(td);
2046 * Fork a new thread, may be within the same process.
2049 sched_fork_thread(struct thread *td, struct thread *child)
2051 struct td_sched *ts;
2052 struct td_sched *ts2;
2056 THREAD_LOCK_ASSERT(td, MA_OWNED);
2061 ts2 = child->td_sched;
2062 child->td_lock = TDQ_LOCKPTR(tdq);
2063 child->td_cpuset = cpuset_ref(td->td_cpuset);
2064 ts2->ts_cpu = ts->ts_cpu;
2067 * Grab our parents cpu estimation information.
2069 ts2->ts_ticks = ts->ts_ticks;
2070 ts2->ts_ltick = ts->ts_ltick;
2071 ts2->ts_ftick = ts->ts_ftick;
2073 * Do not inherit any borrowed priority from the parent.
2075 child->td_priority = child->td_base_pri;
2077 * And update interactivity score.
2079 ts2->ts_slptime = ts->ts_slptime;
2080 ts2->ts_runtime = ts->ts_runtime;
2081 /* Attempt to quickly learn interactivity. */
2082 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min;
2084 bzero(ts2->ts_name, sizeof(ts2->ts_name));
2089 * Adjust the priority class of a thread.
2092 sched_class(struct thread *td, int class)
2095 THREAD_LOCK_ASSERT(td, MA_OWNED);
2096 if (td->td_pri_class == class)
2098 td->td_pri_class = class;
2102 * Return some of the child's priority and interactivity to the parent.
2105 sched_exit(struct proc *p, struct thread *child)
2109 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit",
2110 "prio:%d", child->td_priority);
2111 PROC_LOCK_ASSERT(p, MA_OWNED);
2112 td = FIRST_THREAD_IN_PROC(p);
2113 sched_exit_thread(td, child);
2117 * Penalize another thread for the time spent on this one. This helps to
2118 * worsen the priority and interactivity of processes which schedule batch
2119 * jobs such as make. This has little effect on the make process itself but
2120 * causes new processes spawned by it to receive worse scores immediately.
2123 sched_exit_thread(struct thread *td, struct thread *child)
2126 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit",
2127 "prio:%d", child->td_priority);
2129 * Give the child's runtime to the parent without returning the
2130 * sleep time as a penalty to the parent. This causes shells that
2131 * launch expensive things to mark their children as expensive.
2134 td->td_sched->ts_runtime += child->td_sched->ts_runtime;
2135 sched_interact_update(td);
2141 sched_preempt(struct thread *td)
2145 SDT_PROBE2(sched, , , surrender, td, td->td_proc);
2149 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2150 tdq->tdq_ipipending = 0;
2151 if (td->td_priority > tdq->tdq_lowpri) {
2154 flags = SW_INVOL | SW_PREEMPT;
2155 if (td->td_critnest > 1)
2156 td->td_owepreempt = 1;
2157 else if (TD_IS_IDLETHREAD(td))
2158 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL);
2160 mi_switch(flags | SWT_REMOTEPREEMPT, NULL);
2166 * Fix priorities on return to user-space. Priorities may be elevated due
2167 * to static priorities in msleep() or similar.
2170 sched_userret(struct thread *td)
2173 * XXX we cheat slightly on the locking here to avoid locking in
2174 * the usual case. Setting td_priority here is essentially an
2175 * incomplete workaround for not setting it properly elsewhere.
2176 * Now that some interrupt handlers are threads, not setting it
2177 * properly elsewhere can clobber it in the window between setting
2178 * it here and returning to user mode, so don't waste time setting
2179 * it perfectly here.
2181 KASSERT((td->td_flags & TDF_BORROWING) == 0,
2182 ("thread with borrowed priority returning to userland"));
2183 if (td->td_priority != td->td_user_pri) {
2185 td->td_priority = td->td_user_pri;
2186 td->td_base_pri = td->td_user_pri;
2187 tdq_setlowpri(TDQ_SELF(), td);
2193 * Handle a stathz tick. This is really only relevant for timeshare
2197 sched_clock(struct thread *td)
2200 struct td_sched *ts;
2202 THREAD_LOCK_ASSERT(td, MA_OWNED);
2206 * We run the long term load balancer infrequently on the first cpu.
2208 if (balance_tdq == tdq) {
2209 if (balance_ticks && --balance_ticks == 0)
2214 * Save the old switch count so we have a record of the last ticks
2215 * activity. Initialize the new switch count based on our load.
2216 * If there is some activity seed it to reflect that.
2218 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt;
2219 tdq->tdq_switchcnt = tdq->tdq_load;
2221 * Advance the insert index once for each tick to ensure that all
2222 * threads get a chance to run.
2224 if (tdq->tdq_idx == tdq->tdq_ridx) {
2225 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS;
2226 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx]))
2227 tdq->tdq_ridx = tdq->tdq_idx;
2230 sched_pctcpu_update(ts, 1);
2231 if (td->td_pri_class & PRI_FIFO_BIT)
2233 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) {
2235 * We used a tick; charge it to the thread so
2236 * that we can compute our interactivity.
2238 td->td_sched->ts_runtime += tickincr;
2239 sched_interact_update(td);
2244 * Force a context switch if the current thread has used up a full
2245 * time slice (default is 100ms).
2247 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) {
2249 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND;
2254 * Called once per hz tick.
2263 * Return whether the current CPU has runnable tasks. Used for in-kernel
2264 * cooperative idle threads.
2267 sched_runnable(void)
2275 if ((curthread->td_flags & TDF_IDLETD) != 0) {
2276 if (tdq->tdq_load > 0)
2279 if (tdq->tdq_load - 1 > 0)
2287 * Choose the highest priority thread to run. The thread is removed from
2288 * the run-queue while running however the load remains. For SMP we set
2289 * the tdq in the global idle bitmask if it idles here.
2298 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2299 td = tdq_choose(tdq);
2301 tdq_runq_rem(tdq, td);
2302 tdq->tdq_lowpri = td->td_priority;
2305 tdq->tdq_lowpri = PRI_MAX_IDLE;
2306 return (PCPU_GET(idlethread));
2310 * Set owepreempt if necessary. Preemption never happens directly in ULE,
2311 * we always request it once we exit a critical section.
2314 sched_setpreempt(struct thread *td)
2320 THREAD_LOCK_ASSERT(curthread, MA_OWNED);
2323 pri = td->td_priority;
2324 cpri = ctd->td_priority;
2326 ctd->td_flags |= TDF_NEEDRESCHED;
2327 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd))
2329 if (!sched_shouldpreempt(pri, cpri, 0))
2331 ctd->td_owepreempt = 1;
2335 * Add a thread to a thread queue. Select the appropriate runq and add the
2336 * thread to it. This is the internal function called when the tdq is
2340 tdq_add(struct tdq *tdq, struct thread *td, int flags)
2343 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2344 KASSERT((td->td_inhibitors == 0),
2345 ("sched_add: trying to run inhibited thread"));
2346 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
2347 ("sched_add: bad thread state"));
2348 KASSERT(td->td_flags & TDF_INMEM,
2349 ("sched_add: thread swapped out"));
2351 if (td->td_priority < tdq->tdq_lowpri)
2352 tdq->tdq_lowpri = td->td_priority;
2353 tdq_runq_add(tdq, td, flags);
2354 tdq_load_add(tdq, td);
2358 * Select the target thread queue and add a thread to it. Request
2359 * preemption or IPI a remote processor if required.
2362 sched_add(struct thread *td, int flags)
2369 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
2370 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
2371 sched_tdname(curthread));
2372 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
2373 KTR_ATTR_LINKED, sched_tdname(td));
2374 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
2375 flags & SRQ_PREEMPTED);
2376 THREAD_LOCK_ASSERT(td, MA_OWNED);
2378 * Recalculate the priority before we select the target cpu or
2381 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
2385 * Pick the destination cpu and if it isn't ours transfer to the
2388 cpu = sched_pickcpu(td, flags);
2389 tdq = sched_setcpu(td, cpu, flags);
2390 tdq_add(tdq, td, flags);
2391 if (cpu != PCPU_GET(cpuid)) {
2392 tdq_notify(tdq, td);
2399 * Now that the thread is moving to the run-queue, set the lock
2400 * to the scheduler's lock.
2402 thread_lock_set(td, TDQ_LOCKPTR(tdq));
2403 tdq_add(tdq, td, flags);
2405 if (!(flags & SRQ_YIELDING))
2406 sched_setpreempt(td);
2410 * Remove a thread from a run-queue without running it. This is used
2411 * when we're stealing a thread from a remote queue. Otherwise all threads
2412 * exit by calling sched_exit_thread() and sched_throw() themselves.
2415 sched_rem(struct thread *td)
2419 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem",
2420 "prio:%d", td->td_priority);
2421 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL);
2422 tdq = TDQ_CPU(td->td_sched->ts_cpu);
2423 TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2424 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2425 KASSERT(TD_ON_RUNQ(td),
2426 ("sched_rem: thread not on run queue"));
2427 tdq_runq_rem(tdq, td);
2428 tdq_load_rem(tdq, td);
2430 if (td->td_priority == tdq->tdq_lowpri)
2431 tdq_setlowpri(tdq, NULL);
2435 * Fetch cpu utilization information. Updates on demand.
2438 sched_pctcpu(struct thread *td)
2441 struct td_sched *ts;
2448 THREAD_LOCK_ASSERT(td, MA_OWNED);
2449 sched_pctcpu_update(ts, TD_IS_RUNNING(td));
2453 /* How many rtick per second ? */
2454 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz);
2455 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT;
2462 * Enforce affinity settings for a thread. Called after adjustments to
2466 sched_affinity(struct thread *td)
2469 struct td_sched *ts;
2471 THREAD_LOCK_ASSERT(td, MA_OWNED);
2473 if (THREAD_CAN_SCHED(td, ts->ts_cpu))
2475 if (TD_ON_RUNQ(td)) {
2477 sched_add(td, SRQ_BORING);
2480 if (!TD_IS_RUNNING(td))
2483 * Force a switch before returning to userspace. If the
2484 * target thread is not running locally send an ipi to force
2487 td->td_flags |= TDF_NEEDRESCHED;
2488 if (td != curthread)
2489 ipi_cpu(ts->ts_cpu, IPI_PREEMPT);
2494 * Bind a thread to a target cpu.
2497 sched_bind(struct thread *td, int cpu)
2499 struct td_sched *ts;
2501 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
2502 KASSERT(td == curthread, ("sched_bind: can only bind curthread"));
2504 if (ts->ts_flags & TSF_BOUND)
2506 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td));
2507 ts->ts_flags |= TSF_BOUND;
2509 if (PCPU_GET(cpuid) == cpu)
2512 /* When we return from mi_switch we'll be on the correct cpu. */
2513 mi_switch(SW_VOL, NULL);
2517 * Release a bound thread.
2520 sched_unbind(struct thread *td)
2522 struct td_sched *ts;
2524 THREAD_LOCK_ASSERT(td, MA_OWNED);
2525 KASSERT(td == curthread, ("sched_unbind: can only bind curthread"));
2527 if ((ts->ts_flags & TSF_BOUND) == 0)
2529 ts->ts_flags &= ~TSF_BOUND;
2534 sched_is_bound(struct thread *td)
2536 THREAD_LOCK_ASSERT(td, MA_OWNED);
2537 return (td->td_sched->ts_flags & TSF_BOUND);
2544 sched_relinquish(struct thread *td)
2547 mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
2552 * Return the total system load.
2563 total += TDQ_CPU(i)->tdq_sysload;
2566 return (TDQ_SELF()->tdq_sysload);
2571 sched_sizeof_proc(void)
2573 return (sizeof(struct proc));
2577 sched_sizeof_thread(void)
2579 return (sizeof(struct thread) + sizeof(struct td_sched));
2583 #define TDQ_IDLESPIN(tdq) \
2584 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0)
2586 #define TDQ_IDLESPIN(tdq) 1
2590 * The actual idle process.
2593 sched_idletd(void *dummy)
2597 int oldswitchcnt, switchcnt;
2600 mtx_assert(&Giant, MA_NOTOWNED);
2603 THREAD_NO_SLEEPING();
2606 if (tdq->tdq_load) {
2608 mi_switch(SW_VOL | SWT_IDLE, NULL);
2611 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2613 if (switchcnt != oldswitchcnt) {
2614 oldswitchcnt = switchcnt;
2615 if (tdq_idled(tdq) == 0)
2618 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2620 oldswitchcnt = switchcnt;
2623 * If we're switching very frequently, spin while checking
2624 * for load rather than entering a low power state that
2625 * may require an IPI. However, don't do any busy
2626 * loops while on SMT machines as this simply steals
2627 * cycles from cores doing useful work.
2629 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) {
2630 for (i = 0; i < sched_idlespins; i++) {
2637 /* If there was context switch during spin, restart it. */
2638 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2639 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt)
2642 /* Run main MD idle handler. */
2643 tdq->tdq_cpu_idle = 1;
2644 cpu_idle(switchcnt * 4 > sched_idlespinthresh);
2645 tdq->tdq_cpu_idle = 0;
2648 * Account thread-less hardware interrupts and
2649 * other wakeup reasons equal to context switches.
2651 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2652 if (switchcnt != oldswitchcnt)
2654 tdq->tdq_switchcnt++;
2660 * A CPU is entering for the first time or a thread is exiting.
2663 sched_throw(struct thread *td)
2665 struct thread *newtd;
2670 /* Correct spinlock nesting and acquire the correct lock. */
2673 PCPU_SET(switchtime, cpu_ticks());
2674 PCPU_SET(switchticks, ticks);
2676 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2677 tdq_load_rem(tdq, td);
2678 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object);
2680 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
2681 newtd = choosethread();
2682 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
2683 cpu_throw(td, newtd); /* doesn't return */
2687 * This is called from fork_exit(). Just acquire the correct locks and
2688 * let fork do the rest of the work.
2691 sched_fork_exit(struct thread *td)
2693 struct td_sched *ts;
2698 * Finish setting up thread glue so that it begins execution in a
2699 * non-nested critical section with the scheduler lock held.
2701 cpuid = PCPU_GET(cpuid);
2702 tdq = TDQ_CPU(cpuid);
2704 if (TD_IS_IDLETHREAD(td))
2705 td->td_lock = TDQ_LOCKPTR(tdq);
2706 MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2707 td->td_oncpu = cpuid;
2708 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
2709 lock_profile_obtain_lock_success(
2710 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__);
2714 * Create on first use to catch odd startup conditons.
2717 sched_tdname(struct thread *td)
2720 struct td_sched *ts;
2723 if (ts->ts_name[0] == '\0')
2724 snprintf(ts->ts_name, sizeof(ts->ts_name),
2725 "%s tid %d", td->td_name, td->td_tid);
2726 return (ts->ts_name);
2728 return (td->td_name);
2734 sched_clear_tdname(struct thread *td)
2736 struct td_sched *ts;
2739 ts->ts_name[0] = '\0';
2746 * Build the CPU topology dump string. Is recursively called to collect
2747 * the topology tree.
2750 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg,
2753 char cpusetbuf[CPUSETBUFSIZ];
2756 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent,
2757 "", 1 + indent / 2, cg->cg_level);
2758 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "",
2759 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask));
2761 for (i = 0; i < MAXCPU; i++) {
2762 if (CPU_ISSET(i, &cg->cg_mask)) {
2764 sbuf_printf(sb, ", ");
2767 sbuf_printf(sb, "%d", i);
2770 sbuf_printf(sb, "</cpu>\n");
2772 if (cg->cg_flags != 0) {
2773 sbuf_printf(sb, "%*s <flags>", indent, "");
2774 if ((cg->cg_flags & CG_FLAG_HTT) != 0)
2775 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>");
2776 if ((cg->cg_flags & CG_FLAG_THREAD) != 0)
2777 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>");
2778 if ((cg->cg_flags & CG_FLAG_SMT) != 0)
2779 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>");
2780 sbuf_printf(sb, "</flags>\n");
2783 if (cg->cg_children > 0) {
2784 sbuf_printf(sb, "%*s <children>\n", indent, "");
2785 for (i = 0; i < cg->cg_children; i++)
2786 sysctl_kern_sched_topology_spec_internal(sb,
2787 &cg->cg_child[i], indent+2);
2788 sbuf_printf(sb, "%*s </children>\n", indent, "");
2790 sbuf_printf(sb, "%*s</group>\n", indent, "");
2795 * Sysctl handler for retrieving topology dump. It's a wrapper for
2796 * the recursive sysctl_kern_smp_topology_spec_internal().
2799 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS)
2804 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized"));
2806 topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND);
2810 sbuf_printf(topo, "<groups>\n");
2811 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1);
2812 sbuf_printf(topo, "</groups>\n");
2816 err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo));
2825 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
2827 int error, new_val, period;
2829 period = 1000000 / realstathz;
2830 new_val = period * sched_slice;
2831 error = sysctl_handle_int(oidp, &new_val, 0, req);
2832 if (error != 0 || req->newptr == NULL)
2836 sched_slice = imax(1, (new_val + period / 2) / period);
2837 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR;
2838 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
2843 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler");
2844 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0,
2846 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW,
2847 NULL, 0, sysctl_kern_quantum, "I",
2848 "Quantum for timeshare threads in microseconds");
2849 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
2850 "Quantum for timeshare threads in stathz ticks");
2851 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0,
2852 "Interactivity score threshold");
2853 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW,
2855 "Maximal (lowest) priority for preemption");
2856 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0,
2857 "Assign static kernel priorities to sleeping threads");
2858 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0,
2859 "Number of times idle thread will spin waiting for new work");
2860 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW,
2861 &sched_idlespinthresh, 0,
2862 "Threshold before we will permit idle thread spinning");
2864 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0,
2865 "Number of hz ticks to keep thread affinity for");
2866 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0,
2867 "Enables the long-term load balancer");
2868 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW,
2869 &balance_interval, 0,
2870 "Average period in stathz ticks to run the long-term balancer");
2871 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0,
2872 "Attempts to steal work from other cores before idling");
2873 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0,
2874 "Minimum load on remote CPU before we'll steal");
2875 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING |
2876 CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A",
2877 "XML dump of detected CPU topology");
2880 /* ps compat. All cpu percentages from ULE are weighted. */
2881 static int ccpu = 0;
2882 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");