diff options
Diffstat (limited to 'sys/kern/sched_ule.c')
-rw-r--r-- | sys/kern/sched_ule.c | 2903 |
1 files changed, 2903 insertions, 0 deletions
diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c new file mode 100644 index 0000000..107a15d --- /dev/null +++ b/sys/kern/sched_ule.c @@ -0,0 +1,2903 @@ +/*- + * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice unmodified, this list of conditions, and the following + * disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +/* + * This file implements the ULE scheduler. ULE supports independent CPU + * run queues and fine grain locking. It has superior interactive + * performance under load even on uni-processor systems. + * + * etymology: + * ULE is the last three letters in schedule. It owes its name to a + * generic user created for a scheduling system by Paul Mikesell at + * Isilon Systems and a general lack of creativity on the part of the author. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include "opt_hwpmc_hooks.h" +#include "opt_kdtrace.h" +#include "opt_sched.h" + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/kdb.h> +#include <sys/kernel.h> +#include <sys/ktr.h> +#include <sys/lock.h> +#include <sys/mutex.h> +#include <sys/proc.h> +#include <sys/resource.h> +#include <sys/resourcevar.h> +#include <sys/sched.h> +#include <sys/sdt.h> +#include <sys/smp.h> +#include <sys/sx.h> +#include <sys/sysctl.h> +#include <sys/sysproto.h> +#include <sys/turnstile.h> +#include <sys/umtx.h> +#include <sys/vmmeter.h> +#include <sys/cpuset.h> +#include <sys/sbuf.h> + +#ifdef HWPMC_HOOKS +#include <sys/pmckern.h> +#endif + +#ifdef KDTRACE_HOOKS +#include <sys/dtrace_bsd.h> +int dtrace_vtime_active; +dtrace_vtime_switch_func_t dtrace_vtime_switch_func; +#endif + +#include <machine/cpu.h> +#include <machine/smp.h> + +#if defined(__powerpc__) && defined(BOOKE_E500) +#error "This architecture is not currently compatible with ULE" +#endif + +#define KTR_ULE 0 + +#define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) +#define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU))) +#define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load")) + +/* + * Thread scheduler specific section. All fields are protected + * by the thread lock. + */ +struct td_sched { + struct runq *ts_runq; /* Run-queue we're queued on. */ + short ts_flags; /* TSF_* flags. */ + u_char ts_cpu; /* CPU that we have affinity for. */ + int ts_rltick; /* Real last tick, for affinity. */ + int ts_slice; /* Ticks of slice remaining. */ + u_int ts_slptime; /* Number of ticks we vol. slept */ + u_int ts_runtime; /* Number of ticks we were running */ + int ts_ltick; /* Last tick that we were running on */ + int ts_ftick; /* First tick that we were running on */ + int ts_ticks; /* Tick count */ +#ifdef KTR + char ts_name[TS_NAME_LEN]; +#endif +}; +/* flags kept in ts_flags */ +#define TSF_BOUND 0x0001 /* Thread can not migrate. */ +#define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ + +static struct td_sched td_sched0; + +#define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0) +#define THREAD_CAN_SCHED(td, cpu) \ + CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) + +/* + * Priority ranges used for interactive and non-interactive timeshare + * threads. The timeshare priorities are split up into four ranges. + * The first range handles interactive threads. The last three ranges + * (NHALF, x, and NHALF) handle non-interactive threads with the outer + * ranges supporting nice values. + */ +#define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1) +#define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2) +#define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE) + +#define PRI_MIN_INTERACT PRI_MIN_TIMESHARE +#define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1) +#define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE) +#define PRI_MAX_BATCH PRI_MAX_TIMESHARE + +/* + * Cpu percentage computation macros and defines. + * + * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. + * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. + * SCHED_TICK_MAX: Maximum number of ticks before scaling back. + * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. + * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. + * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. + */ +#define SCHED_TICK_SECS 10 +#define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) +#define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) +#define SCHED_TICK_SHIFT 10 +#define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) +#define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) + +/* + * These macros determine priorities for non-interactive threads. They are + * assigned a priority based on their recent cpu utilization as expressed + * by the ratio of ticks to the tick total. NHALF priorities at the start + * and end of the MIN to MAX timeshare range are only reachable with negative + * or positive nice respectively. + * + * PRI_RANGE: Priority range for utilization dependent priorities. + * PRI_NRESV: Number of nice values. + * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. + * PRI_NICE: Determines the part of the priority inherited from nice. + */ +#define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) +#define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) +#define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF) +#define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF) +#define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1) +#define SCHED_PRI_TICKS(ts) \ + (SCHED_TICK_HZ((ts)) / \ + (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) +#define SCHED_PRI_NICE(nice) (nice) + +/* + * These determine the interactivity of a process. Interactivity differs from + * cpu utilization in that it expresses the voluntary time slept vs time ran + * while cpu utilization includes all time not running. This more accurately + * models the intent of the thread. + * + * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate + * before throttling back. + * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. + * INTERACT_MAX: Maximum interactivity value. Smaller is better. + * INTERACT_THRESH: Threshold for placement on the current runq. + */ +#define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) +#define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) +#define SCHED_INTERACT_MAX (100) +#define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) +#define SCHED_INTERACT_THRESH (30) + +/* + * These parameters determine the slice behavior for batch work. + */ +#define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */ +#define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */ + +/* Flags kept in td_flags. */ +#define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ + +/* + * tickincr: Converts a stathz tick into a hz domain scaled by + * the shift factor. Without the shift the error rate + * due to rounding would be unacceptably high. + * realstathz: stathz is sometimes 0 and run off of hz. + * sched_slice: Runtime of each thread before rescheduling. + * preempt_thresh: Priority threshold for preemption and remote IPIs. + */ +static int sched_interact = SCHED_INTERACT_THRESH; +static int tickincr = 8 << SCHED_TICK_SHIFT; +static int realstathz = 127; /* reset during boot. */ +static int sched_slice = 10; /* reset during boot. */ +static int sched_slice_min = 1; /* reset during boot. */ +#ifdef PREEMPTION +#ifdef FULL_PREEMPTION +static int preempt_thresh = PRI_MAX_IDLE; +#else +static int preempt_thresh = PRI_MIN_KERN; +#endif +#else +static int preempt_thresh = 0; +#endif +static int static_boost = PRI_MIN_BATCH; +static int sched_idlespins = 10000; +static int sched_idlespinthresh = -1; + +/* + * tdq - per processor runqs and statistics. All fields are protected by the + * tdq_lock. The load and lowpri may be accessed without to avoid excess + * locking in sched_pickcpu(); + */ +struct tdq { + /* + * Ordered to improve efficiency of cpu_search() and switch(). + * tdq_lock is padded to avoid false sharing with tdq_load and + * tdq_cpu_idle. + */ + struct mtx_padalign tdq_lock; /* run queue lock. */ + struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ + volatile int tdq_load; /* Aggregate load. */ + volatile int tdq_cpu_idle; /* cpu_idle() is active. */ + int tdq_sysload; /* For loadavg, !ITHD load. */ + int tdq_transferable; /* Transferable thread count. */ + short tdq_switchcnt; /* Switches this tick. */ + short tdq_oldswitchcnt; /* Switches last tick. */ + u_char tdq_lowpri; /* Lowest priority thread. */ + u_char tdq_ipipending; /* IPI pending. */ + u_char tdq_idx; /* Current insert index. */ + u_char tdq_ridx; /* Current removal index. */ + struct runq tdq_realtime; /* real-time run queue. */ + struct runq tdq_timeshare; /* timeshare run queue. */ + struct runq tdq_idle; /* Queue of IDLE threads. */ + char tdq_name[TDQ_NAME_LEN]; +#ifdef KTR + char tdq_loadname[TDQ_LOADNAME_LEN]; +#endif +} __aligned(64); + +/* Idle thread states and config. */ +#define TDQ_RUNNING 1 +#define TDQ_IDLE 2 + +#ifdef SMP +struct cpu_group *cpu_top; /* CPU topology */ + +#define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) +#define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) + +/* + * Run-time tunables. + */ +static int rebalance = 1; +static int balance_interval = 128; /* Default set in sched_initticks(). */ +static int affinity; +static int steal_idle = 1; +static int steal_thresh = 2; + +/* + * One thread queue per processor. + */ +static struct tdq tdq_cpu[MAXCPU]; +static struct tdq *balance_tdq; +static int balance_ticks; +static DPCPU_DEFINE(uint32_t, randomval); + +#define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)]) +#define TDQ_CPU(x) (&tdq_cpu[(x)]) +#define TDQ_ID(x) ((int)((x) - tdq_cpu)) +#else /* !SMP */ +static struct tdq tdq_cpu; + +#define TDQ_ID(x) (0) +#define TDQ_SELF() (&tdq_cpu) +#define TDQ_CPU(x) (&tdq_cpu) +#endif + +#define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) +#define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) +#define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) +#define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) +#define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock)) + +static void sched_priority(struct thread *); +static void sched_thread_priority(struct thread *, u_char); +static int sched_interact_score(struct thread *); +static void sched_interact_update(struct thread *); +static void sched_interact_fork(struct thread *); +static void sched_pctcpu_update(struct td_sched *, int); + +/* Operations on per processor queues */ +static struct thread *tdq_choose(struct tdq *); +static void tdq_setup(struct tdq *); +static void tdq_load_add(struct tdq *, struct thread *); +static void tdq_load_rem(struct tdq *, struct thread *); +static __inline void tdq_runq_add(struct tdq *, struct thread *, int); +static __inline void tdq_runq_rem(struct tdq *, struct thread *); +static inline int sched_shouldpreempt(int, int, int); +void tdq_print(int cpu); +static void runq_print(struct runq *rq); +static void tdq_add(struct tdq *, struct thread *, int); +#ifdef SMP +static int tdq_move(struct tdq *, struct tdq *); +static int tdq_idled(struct tdq *); +static void tdq_notify(struct tdq *, struct thread *); +static struct thread *tdq_steal(struct tdq *, int); +static struct thread *runq_steal(struct runq *, int); +static int sched_pickcpu(struct thread *, int); +static void sched_balance(void); +static int sched_balance_pair(struct tdq *, struct tdq *); +static inline struct tdq *sched_setcpu(struct thread *, int, int); +static inline void thread_unblock_switch(struct thread *, struct mtx *); +static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); +static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); +static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, + struct cpu_group *cg, int indent); +#endif + +static void sched_setup(void *dummy); +SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); + +static void sched_initticks(void *dummy); +SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, + NULL); + +SDT_PROVIDER_DEFINE(sched); + +SDT_PROBE_DEFINE3(sched, , , change_pri, change-pri, "struct thread *", + "struct proc *", "uint8_t"); +SDT_PROBE_DEFINE3(sched, , , dequeue, dequeue, "struct thread *", + "struct proc *", "void *"); +SDT_PROBE_DEFINE4(sched, , , enqueue, enqueue, "struct thread *", + "struct proc *", "void *", "int"); +SDT_PROBE_DEFINE4(sched, , , lend_pri, lend-pri, "struct thread *", + "struct proc *", "uint8_t", "struct thread *"); +SDT_PROBE_DEFINE2(sched, , , load_change, load-change, "int", "int"); +SDT_PROBE_DEFINE2(sched, , , off_cpu, off-cpu, "struct thread *", + "struct proc *"); +SDT_PROBE_DEFINE(sched, , , on_cpu, on-cpu); +SDT_PROBE_DEFINE(sched, , , remain_cpu, remain-cpu); +SDT_PROBE_DEFINE2(sched, , , surrender, surrender, "struct thread *", + "struct proc *"); + +/* + * Print the threads waiting on a run-queue. + */ +static void +runq_print(struct runq *rq) +{ + struct rqhead *rqh; + struct thread *td; + int pri; + int j; + int i; + + for (i = 0; i < RQB_LEN; i++) { + printf("\t\trunq bits %d 0x%zx\n", + i, rq->rq_status.rqb_bits[i]); + for (j = 0; j < RQB_BPW; j++) + if (rq->rq_status.rqb_bits[i] & (1ul << j)) { + pri = j + (i << RQB_L2BPW); + rqh = &rq->rq_queues[pri]; + TAILQ_FOREACH(td, rqh, td_runq) { + printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", + td, td->td_name, td->td_priority, + td->td_rqindex, pri); + } + } + } +} + +/* + * Print the status of a per-cpu thread queue. Should be a ddb show cmd. + */ +void +tdq_print(int cpu) +{ + struct tdq *tdq; + + tdq = TDQ_CPU(cpu); + + printf("tdq %d:\n", TDQ_ID(tdq)); + printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); + printf("\tLock name: %s\n", tdq->tdq_name); + printf("\tload: %d\n", tdq->tdq_load); + printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); + printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); + printf("\ttimeshare idx: %d\n", tdq->tdq_idx); + printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); + printf("\tload transferable: %d\n", tdq->tdq_transferable); + printf("\tlowest priority: %d\n", tdq->tdq_lowpri); + printf("\trealtime runq:\n"); + runq_print(&tdq->tdq_realtime); + printf("\ttimeshare runq:\n"); + runq_print(&tdq->tdq_timeshare); + printf("\tidle runq:\n"); + runq_print(&tdq->tdq_idle); +} + +static inline int +sched_shouldpreempt(int pri, int cpri, int remote) +{ + /* + * If the new priority is not better than the current priority there is + * nothing to do. + */ + if (pri >= cpri) + return (0); + /* + * Always preempt idle. + */ + if (cpri >= PRI_MIN_IDLE) + return (1); + /* + * If preemption is disabled don't preempt others. + */ + if (preempt_thresh == 0) + return (0); + /* + * Preempt if we exceed the threshold. + */ + if (pri <= preempt_thresh) + return (1); + /* + * If we're interactive or better and there is non-interactive + * or worse running preempt only remote processors. + */ + if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT) + return (1); + return (0); +} + +/* + * Add a thread to the actual run-queue. Keeps transferable counts up to + * date with what is actually on the run-queue. Selects the correct + * queue position for timeshare threads. + */ +static __inline void +tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) +{ + struct td_sched *ts; + u_char pri; + + TDQ_LOCK_ASSERT(tdq, MA_OWNED); + THREAD_LOCK_ASSERT(td, MA_OWNED); + + pri = td->td_priority; + ts = td->td_sched; + TD_SET_RUNQ(td); + if (THREAD_CAN_MIGRATE(td)) { + tdq->tdq_transferable++; + ts->ts_flags |= TSF_XFERABLE; + } + if (pri < PRI_MIN_BATCH) { + ts->ts_runq = &tdq->tdq_realtime; + } else if (pri <= PRI_MAX_BATCH) { + ts->ts_runq = &tdq->tdq_timeshare; + KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH, + ("Invalid priority %d on timeshare runq", pri)); + /* + * This queue contains only priorities between MIN and MAX + * realtime. Use the whole queue to represent these values. + */ + if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { + pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE; + pri = (pri + tdq->tdq_idx) % RQ_NQS; + /* + * This effectively shortens the queue by one so we + * can have a one slot difference between idx and + * ridx while we wait for threads to drain. + */ + if (tdq->tdq_ridx != tdq->tdq_idx && + pri == tdq->tdq_ridx) + pri = (unsigned char)(pri - 1) % RQ_NQS; + } else + pri = tdq->tdq_ridx; + runq_add_pri(ts->ts_runq, td, pri, flags); + return; + } else + ts->ts_runq = &tdq->tdq_idle; + runq_add(ts->ts_runq, td, flags); +} + +/* + * Remove a thread from a run-queue. This typically happens when a thread + * is selected to run. Running threads are not on the queue and the + * transferable count does not reflect them. + */ +static __inline void +tdq_runq_rem(struct tdq *tdq, struct thread *td) +{ + struct td_sched *ts; + + ts = td->td_sched; + TDQ_LOCK_ASSERT(tdq, MA_OWNED); + KASSERT(ts->ts_runq != NULL, + ("tdq_runq_remove: thread %p null ts_runq", td)); + if (ts->ts_flags & TSF_XFERABLE) { + tdq->tdq_transferable--; + ts->ts_flags &= ~TSF_XFERABLE; + } + if (ts->ts_runq == &tdq->tdq_timeshare) { + if (tdq->tdq_idx != tdq->tdq_ridx) + runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); + else + runq_remove_idx(ts->ts_runq, td, NULL); + } else + runq_remove(ts->ts_runq, td); +} + +/* + * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load + * for this thread to the referenced thread queue. + */ +static void +tdq_load_add(struct tdq *tdq, struct thread *td) +{ + + TDQ_LOCK_ASSERT(tdq, MA_OWNED); + THREAD_LOCK_ASSERT(td, MA_OWNED); + + tdq->tdq_load++; + if ((td->td_flags & TDF_NOLOAD) == 0) + tdq->tdq_sysload++; + KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); + SDT_PROBE2(sched, , , load_change, (int)TDQ_ID(tdq), tdq->tdq_load); +} + +/* + * Remove the load from a thread that is transitioning to a sleep state or + * exiting. + */ +static void +tdq_load_rem(struct tdq *tdq, struct thread *td) +{ + + THREAD_LOCK_ASSERT(td, MA_OWNED); + TDQ_LOCK_ASSERT(tdq, MA_OWNED); + KASSERT(tdq->tdq_load != 0, + ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); + + tdq->tdq_load--; + if ((td->td_flags & TDF_NOLOAD) == 0) + tdq->tdq_sysload--; + KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); + SDT_PROBE2(sched, , , load_change, (int)TDQ_ID(tdq), tdq->tdq_load); +} + +/* + * Bound timeshare latency by decreasing slice size as load increases. We + * consider the maximum latency as the sum of the threads waiting to run + * aside from curthread and target no more than sched_slice latency but + * no less than sched_slice_min runtime. + */ +static inline int +tdq_slice(struct tdq *tdq) +{ + int load; + + /* + * It is safe to use sys_load here because this is called from + * contexts where timeshare threads are running and so there + * cannot be higher priority load in the system. + */ + load = tdq->tdq_sysload - 1; + if (load >= SCHED_SLICE_MIN_DIVISOR) + return (sched_slice_min); + if (load <= 1) + return (sched_slice); + return (sched_slice / load); +} + +/* + * Set lowpri to its exact value by searching the run-queue and + * evaluating curthread. curthread may be passed as an optimization. + */ +static void +tdq_setlowpri(struct tdq *tdq, struct thread *ctd) +{ + struct thread *td; + + TDQ_LOCK_ASSERT(tdq, MA_OWNED); + if (ctd == NULL) + ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread; + td = tdq_choose(tdq); + if (td == NULL || td->td_priority > ctd->td_priority) + tdq->tdq_lowpri = ctd->td_priority; + else + tdq->tdq_lowpri = td->td_priority; +} + +#ifdef SMP +struct cpu_search { + cpuset_t cs_mask; + u_int cs_prefer; + int cs_pri; /* Min priority for low. */ + int cs_limit; /* Max load for low, min load for high. */ + int cs_cpu; + int cs_load; +}; + +#define CPU_SEARCH_LOWEST 0x1 +#define CPU_SEARCH_HIGHEST 0x2 +#define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) + +#define CPUSET_FOREACH(cpu, mask) \ + for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \ + if (CPU_ISSET(cpu, &mask)) + +static __inline int cpu_search(const struct cpu_group *cg, struct cpu_search *low, + struct cpu_search *high, const int match); +int cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low); +int cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high); +int cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, + struct cpu_search *high); + +/* + * Search the tree of cpu_groups for the lowest or highest loaded cpu + * according to the match argument. This routine actually compares the + * load on all paths through the tree and finds the least loaded cpu on + * the least loaded path, which may differ from the least loaded cpu in + * the system. This balances work among caches and busses. + * + * This inline is instantiated in three forms below using constants for the + * match argument. It is reduced to the minimum set for each case. It is + * also recursive to the depth of the tree. + */ +static __inline int +cpu_search(const struct cpu_group *cg, struct cpu_search *low, + struct cpu_search *high, const int match) +{ + struct cpu_search lgroup; + struct cpu_search hgroup; + cpuset_t cpumask; + struct cpu_group *child; + struct tdq *tdq; + int cpu, i, hload, lload, load, total, rnd, *rndptr; + + total = 0; + cpumask = cg->cg_mask; + if (match & CPU_SEARCH_LOWEST) { + lload = INT_MAX; + lgroup = *low; + } + if (match & CPU_SEARCH_HIGHEST) { + hload = INT_MIN; + hgroup = *high; + } + + /* Iterate through the child CPU groups and then remaining CPUs. */ + for (i = cg->cg_children, cpu = mp_maxid; i >= 0; ) { + if (i == 0) { + while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask)) + cpu--; + if (cpu < 0) + break; + child = NULL; + } else + child = &cg->cg_child[i - 1]; + + if (match & CPU_SEARCH_LOWEST) + lgroup.cs_cpu = -1; + if (match & CPU_SEARCH_HIGHEST) + hgroup.cs_cpu = -1; + if (child) { /* Handle child CPU group. */ + CPU_NAND(&cpumask, &child->cg_mask); + switch (match) { + case CPU_SEARCH_LOWEST: + load = cpu_search_lowest(child, &lgroup); + break; + case CPU_SEARCH_HIGHEST: + load = cpu_search_highest(child, &hgroup); + break; + case CPU_SEARCH_BOTH: + load = cpu_search_both(child, &lgroup, &hgroup); + break; + } + } else { /* Handle child CPU. */ + tdq = TDQ_CPU(cpu); + load = tdq->tdq_load * 256; + rndptr = DPCPU_PTR(randomval); + rnd = (*rndptr = *rndptr * 69069 + 5) >> 26; + if (match & CPU_SEARCH_LOWEST) { + if (cpu == low->cs_prefer) + load -= 64; + /* If that CPU is allowed and get data. */ + if (tdq->tdq_lowpri > lgroup.cs_pri && + tdq->tdq_load <= lgroup.cs_limit && + CPU_ISSET(cpu, &lgroup.cs_mask)) { + lgroup.cs_cpu = cpu; + lgroup.cs_load = load - rnd; + } + } + if (match & CPU_SEARCH_HIGHEST) + if (tdq->tdq_load >= hgroup.cs_limit && + tdq->tdq_transferable && + CPU_ISSET(cpu, &hgroup.cs_mask)) { + hgroup.cs_cpu = cpu; + hgroup.cs_load = load - rnd; + } + } + total += load; + + /* We have info about child item. Compare it. */ + if (match & CPU_SEARCH_LOWEST) { + if (lgroup.cs_cpu >= 0 && + (load < lload || + (load == lload && lgroup.cs_load < low->cs_load))) { + lload = load; + low->cs_cpu = lgroup.cs_cpu; + low->cs_load = lgroup.cs_load; + } + } + if (match & CPU_SEARCH_HIGHEST) + if (hgroup.cs_cpu >= 0 && + (load > hload || + (load == hload && hgroup.cs_load > high->cs_load))) { + hload = load; + high->cs_cpu = hgroup.cs_cpu; + high->cs_load = hgroup.cs_load; + } + if (child) { + i--; + if (i == 0 && CPU_EMPTY(&cpumask)) + break; + } else + cpu--; + } + return (total); +} + +/* + * cpu_search instantiations must pass constants to maintain the inline + * optimization. + */ +int +cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low) +{ + return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); +} + +int +cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high) +{ + return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); +} + +int +cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, + struct cpu_search *high) +{ + return cpu_search(cg, low, high, CPU_SEARCH_BOTH); +} + +/* + * Find the cpu with the least load via the least loaded path that has a + * lowpri greater than pri pri. A pri of -1 indicates any priority is + * acceptable. + */ +static inline int +sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload, + int prefer) +{ + struct cpu_search low; + + low.cs_cpu = -1; + low.cs_prefer = prefer; + low.cs_mask = mask; + low.cs_pri = pri; + low.cs_limit = maxload; + cpu_search_lowest(cg, &low); + return low.cs_cpu; +} + +/* + * Find the cpu with the highest load via the highest loaded path. + */ +static inline int +sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload) +{ + struct cpu_search high; + + high.cs_cpu = -1; + high.cs_mask = mask; + high.cs_limit = minload; + cpu_search_highest(cg, &high); + return high.cs_cpu; +} + +/* + * Simultaneously find the highest and lowest loaded cpu reachable via + * cg. + */ +static inline void +sched_both(const struct cpu_group *cg, cpuset_t mask, int *lowcpu, int *highcpu) +{ + struct cpu_search high; + struct cpu_search low; + + low.cs_cpu = -1; + low.cs_prefer = -1; + low.cs_pri = -1; + low.cs_limit = INT_MAX; + low.cs_mask = mask; + high.cs_cpu = -1; + high.cs_limit = -1; + high.cs_mask = mask; + cpu_search_both(cg, &low, &high); + *lowcpu = low.cs_cpu; + *highcpu = high.cs_cpu; + return; +} + +static void +sched_balance_group(struct cpu_group *cg) +{ + cpuset_t hmask, lmask; + int high, low, anylow; + + CPU_FILL(&hmask); + for (;;) { + high = sched_highest(cg, hmask, 1); + /* Stop if there is no more CPU with transferrable threads. */ + if (high == -1) + break; + CPU_CLR(high, &hmask); + CPU_COPY(&hmask, &lmask); + /* Stop if there is no more CPU left for low. */ + if (CPU_EMPTY(&lmask)) + break; + anylow = 1; +nextlow: + low = sched_lowest(cg, lmask, -1, + TDQ_CPU(high)->tdq_load - 1, high); + /* Stop if we looked well and found no less loaded CPU. */ + if (anylow && low == -1) + break; + /* Go to next high if we found no less loaded CPU. */ + if (low == -1) + continue; + /* Transfer thread from high to low. */ + if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) { + /* CPU that got thread can no longer be a donor. */ + CPU_CLR(low, &hmask); + } else { + /* + * If failed, then there is no threads on high + * that can run on this low. Drop low from low + * mask and look for different one. + */ + CPU_CLR(low, &lmask); + anylow = 0; + goto nextlow; + } + } +} + +static void +sched_balance(void) +{ + struct tdq *tdq; + + /* + * Select a random time between .5 * balance_interval and + * 1.5 * balance_interval. + */ + balance_ticks = max(balance_interval / 2, 1); + balance_ticks += random() % balance_interval; + if (smp_started == 0 || rebalance == 0) + return; + tdq = TDQ_SELF(); + TDQ_UNLOCK(tdq); + sched_balance_group(cpu_top); + TDQ_LOCK(tdq); +} + +/* + * Lock two thread queues using their address to maintain lock order. + */ +static void +tdq_lock_pair(struct tdq *one, struct tdq *two) +{ + if (one < two) { + TDQ_LOCK(one); + TDQ_LOCK_FLAGS(two, MTX_DUPOK); + } else { + TDQ_LOCK(two); + TDQ_LOCK_FLAGS(one, MTX_DUPOK); + } +} + +/* + * Unlock two thread queues. Order is not important here. + */ +static void +tdq_unlock_pair(struct tdq *one, struct tdq *two) +{ + TDQ_UNLOCK(one); + TDQ_UNLOCK(two); +} + +/* + * Transfer load between two imbalanced thread queues. + */ +static int +sched_balance_pair(struct tdq *high, struct tdq *low) +{ + int moved; + int cpu; + + tdq_lock_pair(high, low); + moved = 0; + /* + * Determine what the imbalance is and then adjust that to how many + * threads we actually have to give up (transferable). + */ + if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && + (moved = tdq_move(high, low)) > 0) { + /* + * In case the target isn't the current cpu IPI it to force a + * reschedule with the new workload. + */ + cpu = TDQ_ID(low); + if (cpu != PCPU_GET(cpuid)) + ipi_cpu(cpu, IPI_PREEMPT); + } + tdq_unlock_pair(high, low); + return (moved); +} + +/* + * Move a thread from one thread queue to another. + */ +static int +tdq_move(struct tdq *from, struct tdq *to) +{ + struct td_sched *ts; + struct thread *td; + struct tdq *tdq; + int cpu; + + TDQ_LOCK_ASSERT(from, MA_OWNED); + TDQ_LOCK_ASSERT(to, MA_OWNED); + + tdq = from; + cpu = TDQ_ID(to); + td = tdq_steal(tdq, cpu); + if (td == NULL) + return (0); + ts = td->td_sched; + /* + * Although the run queue is locked the thread may be blocked. Lock + * it to clear this and acquire the run-queue lock. + */ + thread_lock(td); + /* Drop recursive lock on from acquired via thread_lock(). */ + TDQ_UNLOCK(from); + sched_rem(td); + ts->ts_cpu = cpu; + td->td_lock = TDQ_LOCKPTR(to); + tdq_add(to, td, SRQ_YIELDING); + return (1); +} + +/* + * This tdq has idled. Try to steal a thread from another cpu and switch + * to it. + */ +static int +tdq_idled(struct tdq *tdq) +{ + struct cpu_group *cg; + struct tdq *steal; + cpuset_t mask; + int thresh; + int cpu; + + if (smp_started == 0 || steal_idle == 0) + return (1); + CPU_FILL(&mask); + CPU_CLR(PCPU_GET(cpuid), &mask); + /* We don't want to be preempted while we're iterating. */ + spinlock_enter(); + for (cg = tdq->tdq_cg; cg != NULL; ) { + if ((cg->cg_flags & CG_FLAG_THREAD) == 0) + thresh = steal_thresh; + else + thresh = 1; + cpu = sched_highest(cg, mask, thresh); + if (cpu == -1) { + cg = cg->cg_parent; + continue; + } + steal = TDQ_CPU(cpu); + CPU_CLR(cpu, &mask); + tdq_lock_pair(tdq, steal); + if (steal->tdq_load < thresh || steal->tdq_transferable == 0) { + tdq_unlock_pair(tdq, steal); + continue; + } + /* + * If a thread was added while interrupts were disabled don't + * steal one here. If we fail to acquire one due to affinity + * restrictions loop again with this cpu removed from the + * set. + */ + if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) { + tdq_unlock_pair(tdq, steal); + continue; + } + spinlock_exit(); + TDQ_UNLOCK(steal); + mi_switch(SW_VOL | SWT_IDLE, NULL); + thread_unlock(curthread); + + return (0); + } + spinlock_exit(); + return (1); +} + +/* + * Notify a remote cpu of new work. Sends an IPI if criteria are met. + */ +static void +tdq_notify(struct tdq *tdq, struct thread *td) +{ + struct thread *ctd; + int pri; + int cpu; + + if (tdq->tdq_ipipending) + return; + cpu = td->td_sched->ts_cpu; + pri = td->td_priority; + ctd = pcpu_find(cpu)->pc_curthread; + if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) + return; + if (TD_IS_IDLETHREAD(ctd)) { + /* + * If the MD code has an idle wakeup routine try that before + * falling back to IPI. + */ + if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) + return; + } + tdq->tdq_ipipending = 1; + ipi_cpu(cpu, IPI_PREEMPT); +} + +/* + * Steals load from a timeshare queue. Honors the rotating queue head + * index. + */ +static struct thread * +runq_steal_from(struct runq *rq, int cpu, u_char start) +{ + struct rqbits *rqb; + struct rqhead *rqh; + struct thread *td, *first; + int bit; + int pri; + int i; + + rqb = &rq->rq_status; + bit = start & (RQB_BPW -1); + pri = 0; + first = NULL; +again: + for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { + if (rqb->rqb_bits[i] == 0) + continue; + if (bit != 0) { + for (pri = bit; pri < RQB_BPW; pri++) + if (rqb->rqb_bits[i] & (1ul << pri)) + break; + if (pri >= RQB_BPW) + continue; + } else + pri = RQB_FFS(rqb->rqb_bits[i]); + pri += (i << RQB_L2BPW); + rqh = &rq->rq_queues[pri]; + TAILQ_FOREACH(td, rqh, td_runq) { + if (first && THREAD_CAN_MIGRATE(td) && + THREAD_CAN_SCHED(td, cpu)) + return (td); + first = td; + } + } + if (start != 0) { + start = 0; + goto again; + } + + if (first && THREAD_CAN_MIGRATE(first) && + THREAD_CAN_SCHED(first, cpu)) + return (first); + return (NULL); +} + +/* + * Steals load from a standard linear queue. + */ +static struct thread * +runq_steal(struct runq *rq, int cpu) +{ + struct rqhead *rqh; + struct rqbits *rqb; + struct thread *td; + int word; + int bit; + + rqb = &rq->rq_status; + for (word = 0; word < RQB_LEN; word++) { + if (rqb->rqb_bits[word] == 0) + continue; + for (bit = 0; bit < RQB_BPW; bit++) { + if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) + continue; + rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; + TAILQ_FOREACH(td, rqh, td_runq) + if (THREAD_CAN_MIGRATE(td) && + THREAD_CAN_SCHED(td, cpu)) + return (td); + } + } + return (NULL); +} + +/* + * Attempt to steal a thread in priority order from a thread queue. + */ +static struct thread * +tdq_steal(struct tdq *tdq, int cpu) +{ + struct thread *td; + + TDQ_LOCK_ASSERT(tdq, MA_OWNED); + if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) + return (td); + if ((td = runq_steal_from(&tdq->tdq_timeshare, + cpu, tdq->tdq_ridx)) != NULL) + return (td); + return (runq_steal(&tdq->tdq_idle, cpu)); +} + +/* + * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the + * current lock and returns with the assigned queue locked. + */ +static inline struct tdq * +sched_setcpu(struct thread *td, int cpu, int flags) +{ + + struct tdq *tdq; + + THREAD_LOCK_ASSERT(td, MA_OWNED); + tdq = TDQ_CPU(cpu); + td->td_sched->ts_cpu = cpu; + /* + * If the lock matches just return the queue. + */ + if (td->td_lock == TDQ_LOCKPTR(tdq)) + return (tdq); +#ifdef notyet + /* + * If the thread isn't running its lockptr is a + * turnstile or a sleepqueue. We can just lock_set without + * blocking. + */ + if (TD_CAN_RUN(td)) { + TDQ_LOCK(tdq); + thread_lock_set(td, TDQ_LOCKPTR(tdq)); + return (tdq); + } +#endif + /* + * The hard case, migration, we need to block the thread first to + * prevent order reversals with other cpus locks. + */ + spinlock_enter(); + thread_lock_block(td); + TDQ_LOCK(tdq); + thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); + spinlock_exit(); + return (tdq); +} + +SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); +SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); +SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); +SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); +SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); +SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); + +static int +sched_pickcpu(struct thread *td, int flags) +{ + struct cpu_group *cg, *ccg; + struct td_sched *ts; + struct tdq *tdq; + cpuset_t mask; + int cpu, pri, self; + + self = PCPU_GET(cpuid); + ts = td->td_sched; + if (smp_started == 0) + return (self); + /* + * Don't migrate a running thread from sched_switch(). + */ + if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) + return (ts->ts_cpu); + /* + * Prefer to run interrupt threads on the processors that generate + * the interrupt. + */ + pri = td->td_priority; + if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && + curthread->td_intr_nesting_level && ts->ts_cpu != self) { + SCHED_STAT_INC(pickcpu_intrbind); + ts->ts_cpu = self; + if (TDQ_CPU(self)->tdq_lowpri > pri) { + SCHED_STAT_INC(pickcpu_affinity); + return (ts->ts_cpu); + } + } + /* + * If the thread can run on the last cpu and the affinity has not + * expired or it is idle run it there. + */ + tdq = TDQ_CPU(ts->ts_cpu); + cg = tdq->tdq_cg; + if (THREAD_CAN_SCHED(td, ts->ts_cpu) && + tdq->tdq_lowpri >= PRI_MIN_IDLE && + SCHED_AFFINITY(ts, CG_SHARE_L2)) { + if (cg->cg_flags & CG_FLAG_THREAD) { + CPUSET_FOREACH(cpu, cg->cg_mask) { + if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) + break; + } + } else + cpu = INT_MAX; + if (cpu > mp_maxid) { + SCHED_STAT_INC(pickcpu_idle_affinity); + return (ts->ts_cpu); + } + } + /* + * Search for the last level cache CPU group in the tree. + * Skip caches with expired affinity time and SMT groups. + * Affinity to higher level caches will be handled less aggressively. + */ + for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { + if (cg->cg_flags & CG_FLAG_THREAD) + continue; + if (!SCHED_AFFINITY(ts, cg->cg_level)) + continue; + ccg = cg; + } + if (ccg != NULL) + cg = ccg; + cpu = -1; + /* Search the group for the less loaded idle CPU we can run now. */ + mask = td->td_cpuset->cs_mask; + if (cg != NULL && cg != cpu_top && + CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0) + cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE), + INT_MAX, ts->ts_cpu); + /* Search globally for the less loaded CPU we can run now. */ + if (cpu == -1) + cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); + /* Search globally for the less loaded CPU. */ + if (cpu == -1) + cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); + KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); + /* + * Compare the lowest loaded cpu to current cpu. + */ + if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && + TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE && + TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) { + SCHED_STAT_INC(pickcpu_local); + cpu = self; + } else + SCHED_STAT_INC(pickcpu_lowest); + if (cpu != ts->ts_cpu) + SCHED_STAT_INC(pickcpu_migration); + return (cpu); +} +#endif + +/* + * Pick the highest priority task we have and return it. + */ +static struct thread * +tdq_choose(struct tdq *tdq) +{ + struct thread *td; + + TDQ_LOCK_ASSERT(tdq, MA_OWNED); + td = runq_choose(&tdq->tdq_realtime); + if (td != NULL) + return (td); + td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); + if (td != NULL) { + KASSERT(td->td_priority >= PRI_MIN_BATCH, + ("tdq_choose: Invalid priority on timeshare queue %d", + td->td_priority)); + return (td); + } + td = runq_choose(&tdq->tdq_idle); + if (td != NULL) { + KASSERT(td->td_priority >= PRI_MIN_IDLE, + ("tdq_choose: Invalid priority on idle queue %d", + td->td_priority)); + return (td); + } + + return (NULL); +} + +/* + * Initialize a thread queue. + */ +static void +tdq_setup(struct tdq *tdq) +{ + + if (bootverbose) + printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); + runq_init(&tdq->tdq_realtime); + runq_init(&tdq->tdq_timeshare); + runq_init(&tdq->tdq_idle); + snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), + "sched lock %d", (int)TDQ_ID(tdq)); + mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", + MTX_SPIN | MTX_RECURSE); +#ifdef KTR + snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), + "CPU %d load", (int)TDQ_ID(tdq)); +#endif +} + +#ifdef SMP +static void +sched_setup_smp(void) +{ + struct tdq *tdq; + int i; + + cpu_top = smp_topo(); + CPU_FOREACH(i) { + tdq = TDQ_CPU(i); + tdq_setup(tdq); + tdq->tdq_cg = smp_topo_find(cpu_top, i); + if (tdq->tdq_cg == NULL) + panic("Can't find cpu group for %d\n", i); + } + balance_tdq = TDQ_SELF(); + sched_balance(); +} +#endif + +/* + * Setup the thread queues and initialize the topology based on MD + * information. + */ +static void +sched_setup(void *dummy) +{ + struct tdq *tdq; + + tdq = TDQ_SELF(); +#ifdef SMP + sched_setup_smp(); +#else + tdq_setup(tdq); +#endif + + /* Add thread0's load since it's running. */ + TDQ_LOCK(tdq); + thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); + tdq_load_add(tdq, &thread0); + tdq->tdq_lowpri = thread0.td_priority; + TDQ_UNLOCK(tdq); +} + +/* + * This routine determines time constants after stathz and hz are setup. + */ +/* ARGSUSED */ +static void +sched_initticks(void *dummy) +{ + int incr; + + realstathz = stathz ? stathz : hz; + sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; + sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; + hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / + realstathz); + + /* + * tickincr is shifted out by 10 to avoid rounding errors due to + * hz not being evenly divisible by stathz on all platforms. + */ + incr = (hz << SCHED_TICK_SHIFT) / realstathz; + /* + * This does not work for values of stathz that are more than + * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. + */ + if (incr == 0) + incr = 1; + tickincr = incr; +#ifdef SMP + /* + * Set the default balance interval now that we know + * what realstathz is. + */ + balance_interval = realstathz; + affinity = SCHED_AFFINITY_DEFAULT; +#endif + if (sched_idlespinthresh < 0) + sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; +} + + +/* + * This is the core of the interactivity algorithm. Determines a score based + * on past behavior. It is the ratio of sleep time to run time scaled to + * a [0, 100] integer. This is the voluntary sleep time of a process, which + * differs from the cpu usage because it does not account for time spent + * waiting on a run-queue. Would be prettier if we had floating point. + */ +static int +sched_interact_score(struct thread *td) +{ + struct td_sched *ts; + int div; + + ts = td->td_sched; + /* + * The score is only needed if this is likely to be an interactive + * task. Don't go through the expense of computing it if there's + * no chance. + */ + if (sched_interact <= SCHED_INTERACT_HALF && + ts->ts_runtime >= ts->ts_slptime) + return (SCHED_INTERACT_HALF); + + if (ts->ts_runtime > ts->ts_slptime) { + div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); + return (SCHED_INTERACT_HALF + + (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); + } + if (ts->ts_slptime > ts->ts_runtime) { + div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); + return (ts->ts_runtime / div); + } + /* runtime == slptime */ + if (ts->ts_runtime) + return (SCHED_INTERACT_HALF); + + /* + * This can happen if slptime and runtime are 0. + */ + return (0); + +} + +/* + * Scale the scheduling priority according to the "interactivity" of this + * process. + */ +static void +sched_priority(struct thread *td) +{ + int score; + int pri; + + if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) + return; + /* + * If the score is interactive we place the thread in the realtime + * queue with a priority that is less than kernel and interrupt + * priorities. These threads are not subject to nice restrictions. + * + * Scores greater than this are placed on the normal timeshare queue + * where the priority is partially decided by the most recent cpu + * utilization and the rest is decided by nice value. + * + * The nice value of the process has a linear effect on the calculated + * score. Negative nice values make it easier for a thread to be + * considered interactive. + */ + score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); + if (score < sched_interact) { + pri = PRI_MIN_INTERACT; + pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / + sched_interact) * score; + KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, + ("sched_priority: invalid interactive priority %d score %d", + pri, score)); + } else { + pri = SCHED_PRI_MIN; + if (td->td_sched->ts_ticks) + pri += min(SCHED_PRI_TICKS(td->td_sched), + SCHED_PRI_RANGE); + pri += SCHED_PRI_NICE(td->td_proc->p_nice); + KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, + ("sched_priority: invalid priority %d: nice %d, " + "ticks %d ftick %d ltick %d tick pri %d", + pri, td->td_proc->p_nice, td->td_sched->ts_ticks, + td->td_sched->ts_ftick, td->td_sched->ts_ltick, + SCHED_PRI_TICKS(td->td_sched))); + } + sched_user_prio(td, pri); + + return; +} + +/* + * This routine enforces a maximum limit on the amount of scheduling history + * kept. It is called after either the slptime or runtime is adjusted. This + * function is ugly due to integer math. + */ +static void +sched_interact_update(struct thread *td) +{ + struct td_sched *ts; + u_int sum; + + ts = td->td_sched; + sum = ts->ts_runtime + ts->ts_slptime; + if (sum < SCHED_SLP_RUN_MAX) + return; + /* + * This only happens from two places: + * 1) We have added an unusual amount of run time from fork_exit. + * 2) We have added an unusual amount of sleep time from sched_sleep(). + */ + if (sum > SCHED_SLP_RUN_MAX * 2) { + if (ts->ts_runtime > ts->ts_slptime) { + ts->ts_runtime = SCHED_SLP_RUN_MAX; + ts->ts_slptime = 1; + } else { + ts->ts_slptime = SCHED_SLP_RUN_MAX; + ts->ts_runtime = 1; + } + return; + } + /* + * If we have exceeded by more than 1/5th then the algorithm below + * will not bring us back into range. Dividing by two here forces + * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] + */ + if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { + ts->ts_runtime /= 2; + ts->ts_slptime /= 2; + return; + } + ts->ts_runtime = (ts->ts_runtime / 5) * 4; + ts->ts_slptime = (ts->ts_slptime / 5) * 4; +} + +/* + * Scale back the interactivity history when a child thread is created. The + * history is inherited from the parent but the thread may behave totally + * differently. For example, a shell spawning a compiler process. We want + * to learn that the compiler is behaving badly very quickly. + */ +static void +sched_interact_fork(struct thread *td) +{ + int ratio; + int sum; + + sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; + if (sum > SCHED_SLP_RUN_FORK) { + ratio = sum / SCHED_SLP_RUN_FORK; + td->td_sched->ts_runtime /= ratio; + td->td_sched->ts_slptime /= ratio; + } +} + +/* + * Called from proc0_init() to setup the scheduler fields. + */ +void +schedinit(void) +{ + + /* + * Set up the scheduler specific parts of proc0. + */ + proc0.p_sched = NULL; /* XXX */ + thread0.td_sched = &td_sched0; + td_sched0.ts_ltick = ticks; + td_sched0.ts_ftick = ticks; + td_sched0.ts_slice = 0; +} + +/* + * This is only somewhat accurate since given many processes of the same + * priority they will switch when their slices run out, which will be + * at most sched_slice stathz ticks. + */ +int +sched_rr_interval(void) +{ + + /* Convert sched_slice from stathz to hz. */ + return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); +} + +/* + * Update the percent cpu tracking information when it is requested or + * the total history exceeds the maximum. We keep a sliding history of + * tick counts that slowly decays. This is less precise than the 4BSD + * mechanism since it happens with less regular and frequent events. + */ +static void +sched_pctcpu_update(struct td_sched *ts, int run) +{ + int t = ticks; + + if (t - ts->ts_ltick >= SCHED_TICK_TARG) { + ts->ts_ticks = 0; + ts->ts_ftick = t - SCHED_TICK_TARG; + } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { + ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * + (ts->ts_ltick - (t - SCHED_TICK_TARG)); + ts->ts_ftick = t - SCHED_TICK_TARG; + } + if (run) + ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; + ts->ts_ltick = t; +} + +/* + * Adjust the priority of a thread. Move it to the appropriate run-queue + * if necessary. This is the back-end for several priority related + * functions. + */ +static void +sched_thread_priority(struct thread *td, u_char prio) +{ + struct td_sched *ts; + struct tdq *tdq; + int oldpri; + + KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", + "prio:%d", td->td_priority, "new prio:%d", prio, + KTR_ATTR_LINKED, sched_tdname(curthread)); + SDT_PROBE3(sched, , , change_pri, td, td->td_proc, prio); + if (td != curthread && prio < td->td_priority) { + KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), + "lend prio", "prio:%d", td->td_priority, "new prio:%d", + prio, KTR_ATTR_LINKED, sched_tdname(td)); + SDT_PROBE4(sched, , , lend_pri, td, td->td_proc, prio, + curthread); + } + ts = td->td_sched; + THREAD_LOCK_ASSERT(td, MA_OWNED); + if (td->td_priority == prio) + return; + /* + * If the priority has been elevated due to priority + * propagation, we may have to move ourselves to a new + * queue. This could be optimized to not re-add in some + * cases. + */ + if (TD_ON_RUNQ(td) && prio < td->td_priority) { + sched_rem(td); + td->td_priority = prio; + sched_add(td, SRQ_BORROWING); + return; + } + /* + * If the thread is currently running we may have to adjust the lowpri + * information so other cpus are aware of our current priority. + */ + if (TD_IS_RUNNING(td)) { + tdq = TDQ_CPU(ts->ts_cpu); + oldpri = td->td_priority; + td->td_priority = prio; + if (prio < tdq->tdq_lowpri) + tdq->tdq_lowpri = prio; + else if (tdq->tdq_lowpri == oldpri) + tdq_setlowpri(tdq, td); + return; + } + td->td_priority = prio; +} + +/* + * Update a thread's priority when it is lent another thread's + * priority. + */ +void +sched_lend_prio(struct thread *td, u_char prio) +{ + + td->td_flags |= TDF_BORROWING; + sched_thread_priority(td, prio); +} + +/* + * Restore a thread's priority when priority propagation is + * over. The prio argument is the minimum priority the thread + * needs to have to satisfy other possible priority lending + * requests. If the thread's regular priority is less + * important than prio, the thread will keep a priority boost + * of prio. + */ +void +sched_unlend_prio(struct thread *td, u_char prio) +{ + u_char base_pri; + + if (td->td_base_pri >= PRI_MIN_TIMESHARE && + td->td_base_pri <= PRI_MAX_TIMESHARE) + base_pri = td->td_user_pri; + else + base_pri = td->td_base_pri; + if (prio >= base_pri) { + td->td_flags &= ~TDF_BORROWING; + sched_thread_priority(td, base_pri); + } else + sched_lend_prio(td, prio); +} + +/* + * Standard entry for setting the priority to an absolute value. + */ +void +sched_prio(struct thread *td, u_char prio) +{ + u_char oldprio; + + /* First, update the base priority. */ + td->td_base_pri = prio; + + /* + * If the thread is borrowing another thread's priority, don't + * ever lower the priority. + */ + if (td->td_flags & TDF_BORROWING && td->td_priority < prio) + return; + + /* Change the real priority. */ + oldprio = td->td_priority; + sched_thread_priority(td, prio); + + /* + * If the thread is on a turnstile, then let the turnstile update + * its state. + */ + if (TD_ON_LOCK(td) && oldprio != prio) + turnstile_adjust(td, oldprio); +} + +/* + * Set the base user priority, does not effect current running priority. + */ +void +sched_user_prio(struct thread *td, u_char prio) +{ + + td->td_base_user_pri = prio; + if (td->td_lend_user_pri <= prio) + return; + td->td_user_pri = prio; +} + +void +sched_lend_user_prio(struct thread *td, u_char prio) +{ + + THREAD_LOCK_ASSERT(td, MA_OWNED); + td->td_lend_user_pri = prio; + td->td_user_pri = min(prio, td->td_base_user_pri); + if (td->td_priority > td->td_user_pri) + sched_prio(td, td->td_user_pri); + else if (td->td_priority != td->td_user_pri) + td->td_flags |= TDF_NEEDRESCHED; +} + +/* + * Handle migration from sched_switch(). This happens only for + * cpu binding. + */ +static struct mtx * +sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) +{ + struct tdq *tdn; + + tdn = TDQ_CPU(td->td_sched->ts_cpu); +#ifdef SMP + tdq_load_rem(tdq, td); + /* + * Do the lock dance required to avoid LOR. We grab an extra + * spinlock nesting to prevent preemption while we're + * not holding either run-queue lock. + */ + spinlock_enter(); + thread_lock_block(td); /* This releases the lock on tdq. */ + + /* + * Acquire both run-queue locks before placing the thread on the new + * run-queue to avoid deadlocks created by placing a thread with a + * blocked lock on the run-queue of a remote processor. The deadlock + * occurs when a third processor attempts to lock the two queues in + * question while the target processor is spinning with its own + * run-queue lock held while waiting for the blocked lock to clear. + */ + tdq_lock_pair(tdn, tdq); + tdq_add(tdn, td, flags); + tdq_notify(tdn, td); + TDQ_UNLOCK(tdn); + spinlock_exit(); +#endif + return (TDQ_LOCKPTR(tdn)); +} + +/* + * Variadic version of thread_lock_unblock() that does not assume td_lock + * is blocked. + */ +static inline void +thread_unblock_switch(struct thread *td, struct mtx *mtx) +{ + atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, + (uintptr_t)mtx); +} + +/* + * Switch threads. This function has to handle threads coming in while + * blocked for some reason, running, or idle. It also must deal with + * migrating a thread from one queue to another as running threads may + * be assigned elsewhere via binding. + */ +void +sched_switch(struct thread *td, struct thread *newtd, int flags) +{ + struct tdq *tdq; + struct td_sched *ts; + struct mtx *mtx; + int srqflag; + int cpuid, preempted; + + THREAD_LOCK_ASSERT(td, MA_OWNED); + KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); + + cpuid = PCPU_GET(cpuid); + tdq = TDQ_CPU(cpuid); + ts = td->td_sched; + mtx = td->td_lock; + sched_pctcpu_update(ts, 1); + ts->ts_rltick = ticks; + td->td_lastcpu = td->td_oncpu; + td->td_oncpu = NOCPU; + preempted = !(td->td_flags & TDF_SLICEEND); + td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); + td->td_owepreempt = 0; + if (!TD_IS_IDLETHREAD(td)) + tdq->tdq_switchcnt++; + /* + * The lock pointer in an idle thread should never change. Reset it + * to CAN_RUN as well. + */ + if (TD_IS_IDLETHREAD(td)) { + MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); + TD_SET_CAN_RUN(td); + } else if (TD_IS_RUNNING(td)) { + MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); + srqflag = preempted ? + SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : + SRQ_OURSELF|SRQ_YIELDING; +#ifdef SMP + if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) + ts->ts_cpu = sched_pickcpu(td, 0); +#endif + if (ts->ts_cpu == cpuid) + tdq_runq_add(tdq, td, srqflag); + else { + KASSERT(THREAD_CAN_MIGRATE(td) || + (ts->ts_flags & TSF_BOUND) != 0, + ("Thread %p shouldn't migrate", td)); + mtx = sched_switch_migrate(tdq, td, srqflag); + } + } else { + /* This thread must be going to sleep. */ + TDQ_LOCK(tdq); + mtx = thread_lock_block(td); + tdq_load_rem(tdq, td); + } + /* + * We enter here with the thread blocked and assigned to the + * appropriate cpu run-queue or sleep-queue and with the current + * thread-queue locked. + */ + TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); + newtd = choosethread(); + /* + * Call the MD code to switch contexts if necessary. + */ + if (td != newtd) { +#ifdef HWPMC_HOOKS + if (PMC_PROC_IS_USING_PMCS(td->td_proc)) + PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); +#endif + SDT_PROBE2(sched, , , off_cpu, td, td->td_proc); + lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); + TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; + sched_pctcpu_update(newtd->td_sched, 0); + +#ifdef KDTRACE_HOOKS + /* + * If DTrace has set the active vtime enum to anything + * other than INACTIVE (0), then it should have set the + * function to call. + */ + if (dtrace_vtime_active) + (*dtrace_vtime_switch_func)(newtd); +#endif + + cpu_switch(td, newtd, mtx); + /* + * We may return from cpu_switch on a different cpu. However, + * we always return with td_lock pointing to the current cpu's + * run queue lock. + */ + cpuid = PCPU_GET(cpuid); + tdq = TDQ_CPU(cpuid); + lock_profile_obtain_lock_success( + &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); + + SDT_PROBE0(sched, , , on_cpu); +#ifdef HWPMC_HOOKS + if (PMC_PROC_IS_USING_PMCS(td->td_proc)) + PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); +#endif + } else { + thread_unblock_switch(td, mtx); + SDT_PROBE0(sched, , , remain_cpu); + } + /* + * Assert that all went well and return. + */ + TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); + MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); + td->td_oncpu = cpuid; +} + +/* + * Adjust thread priorities as a result of a nice request. + */ +void +sched_nice(struct proc *p, int nice) +{ + struct thread *td; + + PROC_LOCK_ASSERT(p, MA_OWNED); + + p->p_nice = nice; + FOREACH_THREAD_IN_PROC(p, td) { + thread_lock(td); + sched_priority(td); + sched_prio(td, td->td_base_user_pri); + thread_unlock(td); + } +} + +/* + * Record the sleep time for the interactivity scorer. + */ +void +sched_sleep(struct thread *td, int prio) +{ + + THREAD_LOCK_ASSERT(td, MA_OWNED); + + td->td_slptick = ticks; + if (TD_IS_SUSPENDED(td) || prio >= PSOCK) + td->td_flags |= TDF_CANSWAP; + if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) + return; + if (static_boost == 1 && prio) + sched_prio(td, prio); + else if (static_boost && td->td_priority > static_boost) + sched_prio(td, static_boost); +} + +/* + * Schedule a thread to resume execution and record how long it voluntarily + * slept. We also update the pctcpu, interactivity, and priority. + */ +void +sched_wakeup(struct thread *td) +{ + struct td_sched *ts; + int slptick; + + THREAD_LOCK_ASSERT(td, MA_OWNED); + ts = td->td_sched; + td->td_flags &= ~TDF_CANSWAP; + /* + * If we slept for more than a tick update our interactivity and + * priority. + */ + slptick = td->td_slptick; + td->td_slptick = 0; + if (slptick && slptick != ticks) { + ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; + sched_interact_update(td); + sched_pctcpu_update(ts, 0); + } + /* + * Reset the slice value since we slept and advanced the round-robin. + */ + ts->ts_slice = 0; + sched_add(td, SRQ_BORING); +} + +/* + * Penalize the parent for creating a new child and initialize the child's + * priority. + */ +void +sched_fork(struct thread *td, struct thread *child) +{ + THREAD_LOCK_ASSERT(td, MA_OWNED); + sched_pctcpu_update(td->td_sched, 1); + sched_fork_thread(td, child); + /* + * Penalize the parent and child for forking. + */ + sched_interact_fork(child); + sched_priority(child); + td->td_sched->ts_runtime += tickincr; + sched_interact_update(td); + sched_priority(td); +} + +/* + * Fork a new thread, may be within the same process. + */ +void +sched_fork_thread(struct thread *td, struct thread *child) +{ + struct td_sched *ts; + struct td_sched *ts2; + struct tdq *tdq; + + tdq = TDQ_SELF(); + THREAD_LOCK_ASSERT(td, MA_OWNED); + /* + * Initialize child. + */ + ts = td->td_sched; + ts2 = child->td_sched; + child->td_lock = TDQ_LOCKPTR(tdq); + child->td_cpuset = cpuset_ref(td->td_cpuset); + ts2->ts_cpu = ts->ts_cpu; + ts2->ts_flags = 0; + /* + * Grab our parents cpu estimation information. + */ + ts2->ts_ticks = ts->ts_ticks; + ts2->ts_ltick = ts->ts_ltick; + ts2->ts_ftick = ts->ts_ftick; + /* + * Do not inherit any borrowed priority from the parent. + */ + child->td_priority = child->td_base_pri; + /* + * And update interactivity score. + */ + ts2->ts_slptime = ts->ts_slptime; + ts2->ts_runtime = ts->ts_runtime; + /* Attempt to quickly learn interactivity. */ + ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; +#ifdef KTR + bzero(ts2->ts_name, sizeof(ts2->ts_name)); +#endif +} + +/* + * Adjust the priority class of a thread. + */ +void +sched_class(struct thread *td, int class) +{ + + THREAD_LOCK_ASSERT(td, MA_OWNED); + if (td->td_pri_class == class) + return; + td->td_pri_class = class; +} + +/* + * Return some of the child's priority and interactivity to the parent. + */ +void +sched_exit(struct proc *p, struct thread *child) +{ + struct thread *td; + + KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", + "prio:%d", child->td_priority); + PROC_LOCK_ASSERT(p, MA_OWNED); + td = FIRST_THREAD_IN_PROC(p); + sched_exit_thread(td, child); +} + +/* + * Penalize another thread for the time spent on this one. This helps to + * worsen the priority and interactivity of processes which schedule batch + * jobs such as make. This has little effect on the make process itself but + * causes new processes spawned by it to receive worse scores immediately. + */ +void +sched_exit_thread(struct thread *td, struct thread *child) +{ + + KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", + "prio:%d", child->td_priority); + /* + * Give the child's runtime to the parent without returning the + * sleep time as a penalty to the parent. This causes shells that + * launch expensive things to mark their children as expensive. + */ + thread_lock(td); + td->td_sched->ts_runtime += child->td_sched->ts_runtime; + sched_interact_update(td); + sched_priority(td); + thread_unlock(td); +} + +void +sched_preempt(struct thread *td) +{ + struct tdq *tdq; + + SDT_PROBE2(sched, , , surrender, td, td->td_proc); + + thread_lock(td); + tdq = TDQ_SELF(); + TDQ_LOCK_ASSERT(tdq, MA_OWNED); + tdq->tdq_ipipending = 0; + if (td->td_priority > tdq->tdq_lowpri) { + int flags; + + flags = SW_INVOL | SW_PREEMPT; + if (td->td_critnest > 1) + td->td_owepreempt = 1; + else if (TD_IS_IDLETHREAD(td)) + mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); + else + mi_switch(flags | SWT_REMOTEPREEMPT, NULL); + } + thread_unlock(td); +} + +/* + * Fix priorities on return to user-space. Priorities may be elevated due + * to static priorities in msleep() or similar. + */ +void +sched_userret(struct thread *td) +{ + /* + * XXX we cheat slightly on the locking here to avoid locking in + * the usual case. Setting td_priority here is essentially an + * incomplete workaround for not setting it properly elsewhere. + * Now that some interrupt handlers are threads, not setting it + * properly elsewhere can clobber it in the window between setting + * it here and returning to user mode, so don't waste time setting + * it perfectly here. + */ + KASSERT((td->td_flags & TDF_BORROWING) == 0, + ("thread with borrowed priority returning to userland")); + if (td->td_priority != td->td_user_pri) { + thread_lock(td); + td->td_priority = td->td_user_pri; + td->td_base_pri = td->td_user_pri; + tdq_setlowpri(TDQ_SELF(), td); + thread_unlock(td); + } +} + +/* + * Handle a stathz tick. This is really only relevant for timeshare + * threads. + */ +void +sched_clock(struct thread *td) +{ + struct tdq *tdq; + struct td_sched *ts; + + THREAD_LOCK_ASSERT(td, MA_OWNED); + tdq = TDQ_SELF(); +#ifdef SMP + /* + * We run the long term load balancer infrequently on the first cpu. + */ + if (balance_tdq == tdq) { + if (balance_ticks && --balance_ticks == 0) + sched_balance(); + } +#endif + /* + * Save the old switch count so we have a record of the last ticks + * activity. Initialize the new switch count based on our load. + * If there is some activity seed it to reflect that. + */ + tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; + tdq->tdq_switchcnt = tdq->tdq_load; + /* + * Advance the insert index once for each tick to ensure that all + * threads get a chance to run. + */ + if (tdq->tdq_idx == tdq->tdq_ridx) { + tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; + if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) + tdq->tdq_ridx = tdq->tdq_idx; + } + ts = td->td_sched; + sched_pctcpu_update(ts, 1); + if (td->td_pri_class & PRI_FIFO_BIT) + return; + if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { + /* + * We used a tick; charge it to the thread so + * that we can compute our interactivity. + */ + td->td_sched->ts_runtime += tickincr; + sched_interact_update(td); + sched_priority(td); + } + + /* + * Force a context switch if the current thread has used up a full + * time slice (default is 100ms). + */ + if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { + ts->ts_slice = 0; + td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; + } +} + +/* + * Called once per hz tick. + */ +void +sched_tick(int cnt) +{ + +} + +/* + * Return whether the current CPU has runnable tasks. Used for in-kernel + * cooperative idle threads. + */ +int +sched_runnable(void) +{ + struct tdq *tdq; + int load; + + load = 1; + + tdq = TDQ_SELF(); + if ((curthread->td_flags & TDF_IDLETD) != 0) { + if (tdq->tdq_load > 0) + goto out; + } else + if (tdq->tdq_load - 1 > 0) + goto out; + load = 0; +out: + return (load); +} + +/* + * Choose the highest priority thread to run. The thread is removed from + * the run-queue while running however the load remains. For SMP we set + * the tdq in the global idle bitmask if it idles here. + */ +struct thread * +sched_choose(void) +{ + struct thread *td; + struct tdq *tdq; + + tdq = TDQ_SELF(); + TDQ_LOCK_ASSERT(tdq, MA_OWNED); + td = tdq_choose(tdq); + if (td) { + tdq_runq_rem(tdq, td); + tdq->tdq_lowpri = td->td_priority; + return (td); + } + tdq->tdq_lowpri = PRI_MAX_IDLE; + return (PCPU_GET(idlethread)); +} + +/* + * Set owepreempt if necessary. Preemption never happens directly in ULE, + * we always request it once we exit a critical section. + */ +static inline void +sched_setpreempt(struct thread *td) +{ + struct thread *ctd; + int cpri; + int pri; + + THREAD_LOCK_ASSERT(curthread, MA_OWNED); + + ctd = curthread; + pri = td->td_priority; + cpri = ctd->td_priority; + if (pri < cpri) + ctd->td_flags |= TDF_NEEDRESCHED; + if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) + return; + if (!sched_shouldpreempt(pri, cpri, 0)) + return; + ctd->td_owepreempt = 1; +} + +/* + * Add a thread to a thread queue. Select the appropriate runq and add the + * thread to it. This is the internal function called when the tdq is + * predetermined. + */ +void +tdq_add(struct tdq *tdq, struct thread *td, int flags) +{ + + TDQ_LOCK_ASSERT(tdq, MA_OWNED); + KASSERT((td->td_inhibitors == 0), + ("sched_add: trying to run inhibited thread")); + KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), + ("sched_add: bad thread state")); + KASSERT(td->td_flags & TDF_INMEM, + ("sched_add: thread swapped out")); + + if (td->td_priority < tdq->tdq_lowpri) + tdq->tdq_lowpri = td->td_priority; + tdq_runq_add(tdq, td, flags); + tdq_load_add(tdq, td); +} + +/* + * Select the target thread queue and add a thread to it. Request + * preemption or IPI a remote processor if required. + */ +void +sched_add(struct thread *td, int flags) +{ + struct tdq *tdq; +#ifdef SMP + int cpu; +#endif + + KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", + "prio:%d", td->td_priority, KTR_ATTR_LINKED, + sched_tdname(curthread)); + KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", + KTR_ATTR_LINKED, sched_tdname(td)); + SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, + flags & SRQ_PREEMPTED); + THREAD_LOCK_ASSERT(td, MA_OWNED); + /* + * Recalculate the priority before we select the target cpu or + * run-queue. + */ + if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) + sched_priority(td); +#ifdef SMP + /* + * Pick the destination cpu and if it isn't ours transfer to the + * target cpu. + */ + cpu = sched_pickcpu(td, flags); + tdq = sched_setcpu(td, cpu, flags); + tdq_add(tdq, td, flags); + if (cpu != PCPU_GET(cpuid)) { + tdq_notify(tdq, td); + return; + } +#else + tdq = TDQ_SELF(); + TDQ_LOCK(tdq); + /* + * Now that the thread is moving to the run-queue, set the lock + * to the scheduler's lock. + */ + thread_lock_set(td, TDQ_LOCKPTR(tdq)); + tdq_add(tdq, td, flags); +#endif + if (!(flags & SRQ_YIELDING)) + sched_setpreempt(td); +} + +/* + * Remove a thread from a run-queue without running it. This is used + * when we're stealing a thread from a remote queue. Otherwise all threads + * exit by calling sched_exit_thread() and sched_throw() themselves. + */ +void +sched_rem(struct thread *td) +{ + struct tdq *tdq; + + KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", + "prio:%d", td->td_priority); + SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); + tdq = TDQ_CPU(td->td_sched->ts_cpu); + TDQ_LOCK_ASSERT(tdq, MA_OWNED); + MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); + KASSERT(TD_ON_RUNQ(td), + ("sched_rem: thread not on run queue")); + tdq_runq_rem(tdq, td); + tdq_load_rem(tdq, td); + TD_SET_CAN_RUN(td); + if (td->td_priority == tdq->tdq_lowpri) + tdq_setlowpri(tdq, NULL); +} + +/* + * Fetch cpu utilization information. Updates on demand. + */ +fixpt_t +sched_pctcpu(struct thread *td) +{ + fixpt_t pctcpu; + struct td_sched *ts; + + pctcpu = 0; + ts = td->td_sched; + if (ts == NULL) + return (0); + + THREAD_LOCK_ASSERT(td, MA_OWNED); + sched_pctcpu_update(ts, TD_IS_RUNNING(td)); + if (ts->ts_ticks) { + int rtick; + + /* How many rtick per second ? */ + rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); + pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; + } + + return (pctcpu); +} + +/* + * Enforce affinity settings for a thread. Called after adjustments to + * cpumask. + */ +void +sched_affinity(struct thread *td) +{ +#ifdef SMP + struct td_sched *ts; + + THREAD_LOCK_ASSERT(td, MA_OWNED); + ts = td->td_sched; + if (THREAD_CAN_SCHED(td, ts->ts_cpu)) + return; + if (TD_ON_RUNQ(td)) { + sched_rem(td); + sched_add(td, SRQ_BORING); + return; + } + if (!TD_IS_RUNNING(td)) + return; + /* + * Force a switch before returning to userspace. If the + * target thread is not running locally send an ipi to force + * the issue. + */ + td->td_flags |= TDF_NEEDRESCHED; + if (td != curthread) + ipi_cpu(ts->ts_cpu, IPI_PREEMPT); +#endif +} + +/* + * Bind a thread to a target cpu. + */ +void +sched_bind(struct thread *td, int cpu) +{ + struct td_sched *ts; + + THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); + KASSERT(td == curthread, ("sched_bind: can only bind curthread")); + ts = td->td_sched; + if (ts->ts_flags & TSF_BOUND) + sched_unbind(td); + KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); + ts->ts_flags |= TSF_BOUND; + sched_pin(); + if (PCPU_GET(cpuid) == cpu) + return; + ts->ts_cpu = cpu; + /* When we return from mi_switch we'll be on the correct cpu. */ + mi_switch(SW_VOL, NULL); +} + +/* + * Release a bound thread. + */ +void +sched_unbind(struct thread *td) +{ + struct td_sched *ts; + + THREAD_LOCK_ASSERT(td, MA_OWNED); + KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); + ts = td->td_sched; + if ((ts->ts_flags & TSF_BOUND) == 0) + return; + ts->ts_flags &= ~TSF_BOUND; + sched_unpin(); +} + +int +sched_is_bound(struct thread *td) +{ + THREAD_LOCK_ASSERT(td, MA_OWNED); + return (td->td_sched->ts_flags & TSF_BOUND); +} + +/* + * Basic yield call. + */ +void +sched_relinquish(struct thread *td) +{ + thread_lock(td); + mi_switch(SW_VOL | SWT_RELINQUISH, NULL); + thread_unlock(td); +} + +/* + * Return the total system load. + */ +int +sched_load(void) +{ +#ifdef SMP + int total; + int i; + + total = 0; + CPU_FOREACH(i) + total += TDQ_CPU(i)->tdq_sysload; + return (total); +#else + return (TDQ_SELF()->tdq_sysload); +#endif +} + +int +sched_sizeof_proc(void) +{ + return (sizeof(struct proc)); +} + +int +sched_sizeof_thread(void) +{ + return (sizeof(struct thread) + sizeof(struct td_sched)); +} + +#ifdef SMP +#define TDQ_IDLESPIN(tdq) \ + ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) +#else +#define TDQ_IDLESPIN(tdq) 1 +#endif + +/* + * The actual idle process. + */ +void +sched_idletd(void *dummy) +{ + struct thread *td; + struct tdq *tdq; + int oldswitchcnt, switchcnt; + int i; + + mtx_assert(&Giant, MA_NOTOWNED); + td = curthread; + tdq = TDQ_SELF(); + THREAD_NO_SLEEPING(); + oldswitchcnt = -1; + for (;;) { + if (tdq->tdq_load) { + thread_lock(td); + mi_switch(SW_VOL | SWT_IDLE, NULL); + thread_unlock(td); + } + switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; +#ifdef SMP + if (switchcnt != oldswitchcnt) { + oldswitchcnt = switchcnt; + if (tdq_idled(tdq) == 0) + continue; + } + switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; +#else + oldswitchcnt = switchcnt; +#endif + /* + * If we're switching very frequently, spin while checking + * for load rather than entering a low power state that + * may require an IPI. However, don't do any busy + * loops while on SMT machines as this simply steals + * cycles from cores doing useful work. + */ + if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { + for (i = 0; i < sched_idlespins; i++) { + if (tdq->tdq_load) + break; + cpu_spinwait(); + } + } + + /* If there was context switch during spin, restart it. */ + switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; + if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) + continue; + + /* Run main MD idle handler. */ + tdq->tdq_cpu_idle = 1; + cpu_idle(switchcnt * 4 > sched_idlespinthresh); + tdq->tdq_cpu_idle = 0; + + /* + * Account thread-less hardware interrupts and + * other wakeup reasons equal to context switches. + */ + switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; + if (switchcnt != oldswitchcnt) + continue; + tdq->tdq_switchcnt++; + oldswitchcnt++; + } +} + +/* + * A CPU is entering for the first time or a thread is exiting. + */ +void +sched_throw(struct thread *td) +{ + struct thread *newtd; + struct tdq *tdq; + + tdq = TDQ_SELF(); + if (td == NULL) { + /* Correct spinlock nesting and acquire the correct lock. */ + TDQ_LOCK(tdq); + spinlock_exit(); + PCPU_SET(switchtime, cpu_ticks()); + PCPU_SET(switchticks, ticks); + } else { + MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); + tdq_load_rem(tdq, td); + lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); + } + KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); + newtd = choosethread(); + TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; + cpu_throw(td, newtd); /* doesn't return */ +} + +/* + * This is called from fork_exit(). Just acquire the correct locks and + * let fork do the rest of the work. + */ +void +sched_fork_exit(struct thread *td) +{ + struct td_sched *ts; + struct tdq *tdq; + int cpuid; + + /* + * Finish setting up thread glue so that it begins execution in a + * non-nested critical section with the scheduler lock held. + */ + cpuid = PCPU_GET(cpuid); + tdq = TDQ_CPU(cpuid); + ts = td->td_sched; + if (TD_IS_IDLETHREAD(td)) + td->td_lock = TDQ_LOCKPTR(tdq); + MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); + td->td_oncpu = cpuid; + TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); + lock_profile_obtain_lock_success( + &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); +} + +/* + * Create on first use to catch odd startup conditons. + */ +char * +sched_tdname(struct thread *td) +{ +#ifdef KTR + struct td_sched *ts; + + ts = td->td_sched; + if (ts->ts_name[0] == '\0') + snprintf(ts->ts_name, sizeof(ts->ts_name), + "%s tid %d", td->td_name, td->td_tid); + return (ts->ts_name); +#else + return (td->td_name); +#endif +} + +#ifdef KTR +void +sched_clear_tdname(struct thread *td) +{ + struct td_sched *ts; + + ts = td->td_sched; + ts->ts_name[0] = '\0'; +} +#endif + +#ifdef SMP + +/* + * Build the CPU topology dump string. Is recursively called to collect + * the topology tree. + */ +static int +sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, + int indent) +{ + char cpusetbuf[CPUSETBUFSIZ]; + int i, first; + + sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, + "", 1 + indent / 2, cg->cg_level); + sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", + cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); + first = TRUE; + for (i = 0; i < MAXCPU; i++) { + if (CPU_ISSET(i, &cg->cg_mask)) { + if (!first) + sbuf_printf(sb, ", "); + else + first = FALSE; + sbuf_printf(sb, "%d", i); + } + } + sbuf_printf(sb, "</cpu>\n"); + + if (cg->cg_flags != 0) { + sbuf_printf(sb, "%*s <flags>", indent, ""); + if ((cg->cg_flags & CG_FLAG_HTT) != 0) + sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); + if ((cg->cg_flags & CG_FLAG_THREAD) != 0) + sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); + if ((cg->cg_flags & CG_FLAG_SMT) != 0) + sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); + sbuf_printf(sb, "</flags>\n"); + } + + if (cg->cg_children > 0) { + sbuf_printf(sb, "%*s <children>\n", indent, ""); + for (i = 0; i < cg->cg_children; i++) + sysctl_kern_sched_topology_spec_internal(sb, + &cg->cg_child[i], indent+2); + sbuf_printf(sb, "%*s </children>\n", indent, ""); + } + sbuf_printf(sb, "%*s</group>\n", indent, ""); + return (0); +} + +/* + * Sysctl handler for retrieving topology dump. It's a wrapper for + * the recursive sysctl_kern_smp_topology_spec_internal(). + */ +static int +sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) +{ + struct sbuf *topo; + int err; + + KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); + + topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND); + if (topo == NULL) + return (ENOMEM); + + sbuf_printf(topo, "<groups>\n"); + err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); + sbuf_printf(topo, "</groups>\n"); + + if (err == 0) { + sbuf_finish(topo); + err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo)); + } + sbuf_delete(topo); + return (err); +} + +#endif + +static int +sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) +{ + int error, new_val, period; + + period = 1000000 / realstathz; + new_val = period * sched_slice; + error = sysctl_handle_int(oidp, &new_val, 0, req); + if (error != 0 || req->newptr == NULL) + return (error); + if (new_val <= 0) + return (EINVAL); + sched_slice = imax(1, (new_val + period / 2) / period); + sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; + hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / + realstathz); + return (0); +} + +SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); +SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, + "Scheduler name"); +SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, + NULL, 0, sysctl_kern_quantum, "I", + "Quantum for timeshare threads in microseconds"); +SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, + "Quantum for timeshare threads in stathz ticks"); +SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, + "Interactivity score threshold"); +SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, + &preempt_thresh, 0, + "Maximal (lowest) priority for preemption"); +SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, + "Assign static kernel priorities to sleeping threads"); +SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, + "Number of times idle thread will spin waiting for new work"); +SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, + &sched_idlespinthresh, 0, + "Threshold before we will permit idle thread spinning"); +#ifdef SMP +SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, + "Number of hz ticks to keep thread affinity for"); +SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, + "Enables the long-term load balancer"); +SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, + &balance_interval, 0, + "Average period in stathz ticks to run the long-term balancer"); +SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, + "Attempts to steal work from other cores before idling"); +SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, + "Minimum load on remote CPU before we'll steal"); +SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | + CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", + "XML dump of detected CPU topology"); +#endif + +/* ps compat. All cpu percentages from ULE are weighted. */ +static int ccpu = 0; +SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); |