/*- * Copyright (c) 2002-2007, Jeffrey Roberson * 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 __FBSDID("$FreeBSD$"); #include "opt_hwpmc_hooks.h" #include "opt_sched.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef KTRACE #include #include #endif #ifdef HWPMC_HOOKS #include #endif #include #include #if !defined(__i386__) && !defined(__amd64__) && !defined(__powerpc__) && !defined(__arm__) #error "This architecture is not currently compatible with ULE" #endif #define KTR_ULE 0 /* * 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 */ }; /* 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) /* * 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_TIMESHARE + SCHED_PRI_NHALF) #define SCHED_PRI_MAX (PRI_MAX_TIMESHARE - SCHED_PRI_NHALF) #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN) #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: Threshhold 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) /* * 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 realstathz; static int tickincr; static int sched_slice = 1; #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 = 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(). */ struct mtx tdq_lock; /* run queue lock. */ struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ int tdq_load; /* Aggregate load. */ int tdq_sysload; /* For loadavg, !ITHD load. */ int tdq_transferable; /* Transferable thread count. */ 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[sizeof("sched lock") + 6]; } __aligned(64); #ifdef SMP struct cpu_group *cpu_top; #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_htt = 1; 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; #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) (&(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 *); /* 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 struct mtx *thread_block_switch(struct thread *); static inline void thread_unblock_switch(struct thread *, struct mtx *); static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); #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); /* * 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("\ttimeshare idx: %d\n", tdq->tdq_idx); printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 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); printf("\tload transferable: %d\n", tdq->tdq_transferable); printf("\tlowest priority: %d\n", tdq->tdq_lowpri); } 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 realtime or better and there is timeshare or worse running * preempt only remote processors. */ if (remote && pri <= PRI_MAX_REALTIME && cpri > PRI_MAX_REALTIME) return (1); return (0); } #define TS_RQ_PPQ (((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) + 1) / RQ_NQS) /* * 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_MAX_REALTIME) { ts->ts_runq = &tdq->tdq_realtime; } else if (pri <= PRI_MAX_TIMESHARE) { ts->ts_runq = &tdq->tdq_timeshare; KASSERT(pri <= PRI_MAX_TIMESHARE && pri >= PRI_MIN_TIMESHARE, ("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 = (pri - PRI_MIN_TIMESHARE) / TS_RQ_PPQ; 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) { struct td_sched *ts; int class; ts = td->td_sched; TDQ_LOCK_ASSERT(tdq, MA_OWNED); THREAD_LOCK_ASSERT(td, MA_OWNED); class = PRI_BASE(td->td_pri_class); tdq->tdq_load++; CTR2(KTR_SCHED, "cpu %d load: %d", TDQ_ID(tdq), tdq->tdq_load); if (class != PRI_ITHD && (td->td_proc->p_flag & P_NOLOAD) == 0) tdq->tdq_sysload++; } /* * 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) { struct td_sched *ts; int class; ts = td->td_sched; THREAD_LOCK_ASSERT(td, MA_OWNED); TDQ_LOCK_ASSERT(tdq, MA_OWNED); class = PRI_BASE(td->td_pri_class); if (class != PRI_ITHD && (td->td_proc->p_flag & P_NOLOAD) == 0) tdq->tdq_sysload--; KASSERT(tdq->tdq_load != 0, ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); tdq->tdq_load--; CTR1(KTR_SCHED, "load: %d", tdq->tdq_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 { cpumask_t cs_mask; /* Mask of valid cpus. */ u_int cs_load; u_int cs_cpu; int cs_limit; /* Min priority for low min load for high. */ }; #define CPU_SEARCH_LOWEST 0x1 #define CPU_SEARCH_HIGHEST 0x2 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) #define CPUMASK_FOREACH(cpu, mask) \ for ((cpu) = 0; (cpu) < sizeof((mask)) * 8; (cpu)++) \ if ((mask) & 1 << (cpu)) static __inline int cpu_search(struct cpu_group *cg, struct cpu_search *low, struct cpu_search *high, const int match); int cpu_search_lowest(struct cpu_group *cg, struct cpu_search *low); int cpu_search_highest(struct cpu_group *cg, struct cpu_search *high); int cpu_search_both(struct cpu_group *cg, struct cpu_search *low, struct cpu_search *high); /* * This routine compares according to the match argument and should be * reduced in actual instantiations via constant propagation and dead code * elimination. */ static __inline int cpu_compare(int cpu, struct cpu_search *low, struct cpu_search *high, const int match) { struct tdq *tdq; tdq = TDQ_CPU(cpu); if (match & CPU_SEARCH_LOWEST) if (low->cs_mask & (1 << cpu) && tdq->tdq_load < low->cs_load && tdq->tdq_lowpri > low->cs_limit) { low->cs_cpu = cpu; low->cs_load = tdq->tdq_load; } if (match & CPU_SEARCH_HIGHEST) if (high->cs_mask & (1 << cpu) && tdq->tdq_load >= high->cs_limit && tdq->tdq_load > high->cs_load && tdq->tdq_transferable) { high->cs_cpu = cpu; high->cs_load = tdq->tdq_load; } return (tdq->tdq_load); } /* * 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(struct cpu_group *cg, struct cpu_search *low, struct cpu_search *high, const int match) { int total; total = 0; if (cg->cg_children) { struct cpu_search lgroup; struct cpu_search hgroup; struct cpu_group *child; u_int lload; int hload; int load; int i; lload = -1; hload = -1; for (i = 0; i < cg->cg_children; i++) { child = &cg->cg_child[i]; if (match & CPU_SEARCH_LOWEST) { lgroup = *low; lgroup.cs_load = -1; } if (match & CPU_SEARCH_HIGHEST) { hgroup = *high; lgroup.cs_load = 0; } 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; } total += load; if (match & CPU_SEARCH_LOWEST) if (load < lload || low->cs_cpu == -1) { *low = lgroup; lload = load; } if (match & CPU_SEARCH_HIGHEST) if (load > hload || high->cs_cpu == -1) { hload = load; *high = hgroup; } } } else { int cpu; CPUMASK_FOREACH(cpu, cg->cg_mask) total += cpu_compare(cpu, low, high, match); } return (total); } /* * cpu_search instantiations must pass constants to maintain the inline * optimization. */ int cpu_search_lowest(struct cpu_group *cg, struct cpu_search *low) { return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); } int cpu_search_highest(struct cpu_group *cg, struct cpu_search *high) { return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); } int cpu_search_both(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(struct cpu_group *cg, cpumask_t mask, int pri) { struct cpu_search low; low.cs_cpu = -1; low.cs_load = -1; low.cs_mask = mask; low.cs_limit = pri; 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(struct cpu_group *cg, cpumask_t mask, int minload) { struct cpu_search high; high.cs_cpu = -1; high.cs_load = 0; 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(struct cpu_group *cg, cpumask_t mask, int *lowcpu, int *highcpu) { struct cpu_search high; struct cpu_search low; low.cs_cpu = -1; low.cs_limit = -1; low.cs_load = -1; low.cs_mask = mask; high.cs_load = 0; 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) { cpumask_t mask; int high; int low; int i; mask = -1; for (;;) { sched_both(cg, mask, &low, &high); if (low == high || low == -1 || high == -1) break; if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) break; /* * If we failed to move any threads determine which cpu * to kick out of the set and try again. */ if (TDQ_CPU(high)->tdq_transferable == 0) mask &= ~(1 << high); else mask &= ~(1 << low); } for (i = 0; i < cg->cg_children; i++) sched_balance_group(&cg->cg_child[i]); } static void sched_balance() { 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 transferable; int high_load; int low_load; int moved; int move; int diff; int i; tdq_lock_pair(high, low); transferable = high->tdq_transferable; high_load = high->tdq_load; low_load = low->tdq_load; moved = 0; /* * Determine what the imbalance is and then adjust that to how many * threads we actually have to give up (transferable). */ if (transferable != 0) { diff = high_load - low_load; move = diff / 2; if (diff & 0x1) move++; move = min(move, transferable); for (i = 0; i < move; i++) moved += tdq_move(high, low); /* * IPI the target cpu to force it to reschedule with the new * workload. */ ipi_selected(1 << TDQ_ID(low), 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; cpumask_t mask; int thresh; int cpu; if (smp_started == 0 || steal_idle == 0) return (1); mask = -1; mask &= ~PCPU_GET(cpumask); /* 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_HTT | 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); mask &= ~(1 << cpu); 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, 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) { int cpri; int pri; int cpu; if (tdq->tdq_ipipending) return; cpu = td->td_sched->ts_cpu; pri = td->td_priority; cpri = pcpu_find(cpu)->pc_curthread->td_priority; if (!sched_shouldpreempt(pri, cpri, 1)) return; tdq->tdq_ipipending = 1; ipi_selected(1 << 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; int first; int bit; int pri; int i; rqb = &rq->rq_status; bit = start & (RQB_BPW -1); pri = 0; first = 0; 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 = 1; } } if (start != 0) { start = 0; goto again; } 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. */ thread_lock_block(td); TDQ_LOCK(tdq); thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); return (tdq); } static int sched_pickcpu(struct thread *td, int flags) { struct cpu_group *cg; struct td_sched *ts; struct tdq *tdq; cpumask_t mask; int self; int pri; int cpu; 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. */ if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && curthread->td_intr_nesting_level) ts->ts_cpu = self; /* * If the thread can run on the last cpu and the affinity has not * expired or it is idle run it there. */ pri = td->td_priority; tdq = TDQ_CPU(ts->ts_cpu); if (THREAD_CAN_SCHED(td, ts->ts_cpu)) { if (tdq->tdq_lowpri > PRI_MIN_IDLE) return (ts->ts_cpu); if (SCHED_AFFINITY(ts, CG_SHARE_L2) && tdq->tdq_lowpri > pri) return (ts->ts_cpu); } /* * Search for the highest level in the tree that still has affinity. */ cg = NULL; for (cg = tdq->tdq_cg; cg != NULL; cg = cg->cg_parent) if (SCHED_AFFINITY(ts, cg->cg_level)) break; cpu = -1; mask = td->td_cpuset->cs_mask.__bits[0]; if (cg) cpu = sched_lowest(cg, mask, pri); if (cpu == -1) cpu = sched_lowest(cpu_top, mask, -1); /* * 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) cpu = self; KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 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_TIMESHARE, ("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 SMP static void sched_setup_smp(void) { struct tdq *tdq; int i; cpu_top = smp_topo(); for (i = 0; i < MAXCPU; i++) { if (CPU_ABSENT(i)) continue; 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 /* * To avoid divide-by-zero, we set realstathz a dummy value * in case which sched_clock() called before sched_initticks(). */ realstathz = hz; sched_slice = (realstathz/10); /* ~100ms */ tickincr = 1 << SCHED_TICK_SHIFT; /* 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 the tickincr after stathz and hz are setup. */ /* ARGSUSED */ static void sched_initticks(void *dummy) { int incr; realstathz = stathz ? stathz : hz; sched_slice = (realstathz/10); /* ~100ms */ /* * 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; /* * Set steal thresh to log2(mp_ncpu) but no greater than 4. This * prevents excess thrashing on large machines and excess idle on * smaller machines. */ steal_thresh = min(ffs(mp_ncpus) - 1, 3); affinity = SCHED_AFFINITY_DEFAULT; #endif } /* * 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 (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_REALTIME; pri += ((PRI_MAX_REALTIME - PRI_MIN_REALTIME) / sched_interact) * score; KASSERT(pri >= PRI_MIN_REALTIME && pri <= PRI_MAX_REALTIME, ("sched_priority: invalid interactive priority %d score %d", pri, score)); } else { pri = SCHED_PRI_MIN; if (td->td_sched->ts_ticks) pri += SCHED_PRI_TICKS(td->td_sched); pri += SCHED_PRI_NICE(td->td_proc->p_nice); KASSERT(pri >= PRI_MIN_TIMESHARE && pri <= PRI_MAX_TIMESHARE, ("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 = sched_slice; } /* * 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 to hz */ return (hz/(realstathz/sched_slice)); } /* * 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) { if (ts->ts_ticks == 0) return; if (ticks - (hz / 10) < ts->ts_ltick && SCHED_TICK_TOTAL(ts) < SCHED_TICK_MAX) return; /* * Adjust counters and watermark for pctcpu calc. */ if (ts->ts_ltick > ticks - SCHED_TICK_TARG) ts->ts_ticks = (ts->ts_ticks / (ticks - ts->ts_ftick)) * SCHED_TICK_TARG; else ts->ts_ticks = 0; ts->ts_ltick = ticks; ts->ts_ftick = ts->ts_ltick - SCHED_TICK_TARG; } /* * 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; CTR6(KTR_SCHED, "sched_prio: %p(%s) prio %d newprio %d by %p(%s)", td, td->td_name, td->td_priority, prio, curthread, curthread->td_name); 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) { u_char oldprio; td->td_base_user_pri = prio; if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio) return; oldprio = td->td_user_pri; td->td_user_pri = prio; } void sched_lend_user_prio(struct thread *td, u_char prio) { u_char oldprio; THREAD_LOCK_ASSERT(td, MA_OWNED); td->td_flags |= TDF_UBORROWING; oldprio = td->td_user_pri; td->td_user_pri = prio; } void sched_unlend_user_prio(struct thread *td, u_char prio) { u_char base_pri; THREAD_LOCK_ASSERT(td, MA_OWNED); base_pri = td->td_base_user_pri; if (prio >= base_pri) { td->td_flags &= ~TDF_UBORROWING; sched_user_prio(td, base_pri); } else { sched_lend_user_prio(td, prio); } } /* * Block a thread for switching. Similar to thread_block() but does not * bump the spin count. */ static inline struct mtx * thread_block_switch(struct thread *td) { struct mtx *lock; THREAD_LOCK_ASSERT(td, MA_OWNED); lock = td->td_lock; td->td_lock = &blocked_lock; mtx_unlock_spin(lock); return (lock); } /* * 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_block_switch(td); /* This releases the lock on tdq. */ TDQ_LOCK(tdn); tdq_add(tdn, td, flags); tdq_notify(tdn, td); /* * After we unlock tdn the new cpu still can't switch into this * thread until we've unblocked it in cpu_switch(). The lock * pointers may match in the case of HTT cores. Don't unlock here * or we can deadlock when the other CPU runs the IPI handler. */ if (TDQ_LOCKPTR(tdn) != TDQ_LOCKPTR(tdq)) { TDQ_UNLOCK(tdn); TDQ_LOCK(tdq); } spinlock_exit(); #endif return (TDQ_LOCKPTR(tdn)); } /* * Release a thread that was blocked with thread_block_switch(). */ 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; 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; ts->ts_rltick = ticks; td->td_lastcpu = td->td_oncpu; td->td_oncpu = NOCPU; td->td_flags &= ~TDF_NEEDRESCHED; td->td_owepreempt = 0; /* * 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 = (flags & SW_PREEMPT) ? SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : SRQ_OURSELF|SRQ_YIELDING; if (ts->ts_cpu == cpuid) tdq_runq_add(tdq, td, srqflag); else mtx = sched_switch_migrate(tdq, td, srqflag); } else { /* This thread must be going to sleep. */ TDQ_LOCK(tdq); mtx = thread_block_switch(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 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 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__); #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); /* * 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 (static_boost && prio) sched_prio(td, prio); } /* * 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) { u_int hzticks; hzticks = (ticks - slptick) << SCHED_TICK_SHIFT; ts->ts_slptime += hzticks; sched_interact_update(td); sched_pctcpu_update(ts); } /* Reset the slice value after we sleep. */ ts->ts_slice = sched_slice; 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_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; THREAD_LOCK_ASSERT(td, MA_OWNED); /* * Initialize child. */ ts = td->td_sched; ts2 = child->td_sched; child->td_lock = TDQ_LOCKPTR(TDQ_SELF()); child->td_cpuset = cpuset_ref(td->td_cpuset); ts2->ts_cpu = ts->ts_cpu; ts2->ts_flags = 0; /* * Grab our parents cpu estimation information and priority. */ ts2->ts_ticks = ts->ts_ticks; ts2->ts_ltick = ts->ts_ltick; ts2->ts_ftick = ts->ts_ftick; child->td_user_pri = td->td_user_pri; child->td_base_user_pri = td->td_base_user_pri; /* * And update interactivity score. */ ts2->ts_slptime = ts->ts_slptime; ts2->ts_runtime = ts->ts_runtime; ts2->ts_slice = 1; /* Attempt to quickly learn interactivity. */ } /* * 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; CTR3(KTR_SCHED, "sched_exit: %p(%s) prio %d", child, child->td_name, 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) { CTR3(KTR_SCHED, "sched_exit_thread: %p(%s) prio %d", child, child->td_name, 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; thread_lock(td); tdq = TDQ_SELF(); TDQ_LOCK_ASSERT(tdq, MA_OWNED); tdq->tdq_ipipending = 0; if (td->td_priority > tdq->tdq_lowpri) { if (td->td_critnest > 1) td->td_owepreempt = 1; else mi_switch(SW_INVOL | SW_PREEMPT, 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 /* * 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; if (td->td_pri_class & PRI_FIFO_BIT) return; if (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); } /* * We used up one time slice. */ if (--ts->ts_slice > 0) return; /* * We're out of time, force a requeue at userret(). */ ts->ts_slice = sched_slice; td->td_flags |= TDF_NEEDRESCHED; } /* * Called once per hz tick. Used for cpu utilization information. This * is easier than trying to scale based on stathz. */ void sched_tick(void) { struct td_sched *ts; ts = curthread->td_sched; /* Adjust ticks for pctcpu */ ts->ts_ticks += 1 << SCHED_TICK_SHIFT; ts->ts_ltick = ticks; /* * Update if we've exceeded our desired tick threshhold by over one * second. */ if (ts->ts_ftick + SCHED_TICK_MAX < ts->ts_ltick) sched_pctcpu_update(ts); } /* * 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) { td->td_sched->ts_ltick = ticks; tdq_runq_rem(tdq, td); return (td); } 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 CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)", td, td->td_name, td->td_priority, curthread, curthread->td_name); 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; CTR5(KTR_SCHED, "sched_rem: %p(%s) prio %d by %p(%s)", td, td->td_name, td->td_priority, curthread, curthread->td_name); 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(td); if (ts->ts_ticks) { int rtick; sched_pctcpu_update(ts); /* How many rtick per second ? */ rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; } thread_unlock(td); 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; int cpu; THREAD_LOCK_ASSERT(td, MA_OWNED); ts = td->td_sched; if (THREAD_CAN_SCHED(td, ts->ts_cpu)) return; if (!TD_IS_RUNNING(td)) return; td->td_flags |= TDF_NEEDRESCHED; if (!THREAD_CAN_MIGRATE(td)) return; /* * Assign the new cpu and force a switch before returning to * userspace. If the target thread is not running locally send * an ipi to force the issue. */ cpu = ts->ts_cpu; ts->ts_cpu = sched_pickcpu(td, 0); if (cpu != PCPU_GET(cpuid)) ipi_selected(1 << 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); ts = td->td_sched; if (ts->ts_flags & TSF_BOUND) sched_unbind(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); 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); SCHED_STAT_INC(switch_relinquish); mi_switch(SW_VOL, NULL); thread_unlock(td); } /* * Return the total system load. */ int sched_load(void) { #ifdef SMP int total; int i; total = 0; for (i = 0; i <= mp_maxid; 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)); } /* * The actual idle process. */ void sched_idletd(void *dummy) { struct thread *td; struct tdq *tdq; td = curthread; tdq = TDQ_SELF(); mtx_assert(&Giant, MA_NOTOWNED); /* ULE relies on preemption for idle interruption. */ for (;;) { #ifdef SMP if (tdq_idled(tdq)) cpu_idle(); #else cpu_idle(); #endif } } /* * 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(); } 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; PCPU_SET(switchtime, cpu_ticks()); PCPU_SET(switchticks, ticks); 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__); } SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, "Scheduler name"); SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, "Slice size for timeshare threads"); 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,"Min priority for preemption, lower priorities have greater precedence"); SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0,"Controls whether static kernel priorities are assigned to sleeping threads."); #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 frequency in stathz ticks to run the long-term balancer"); SYSCTL_INT(_kern_sched, OID_AUTO, steal_htt, CTLFLAG_RW, &steal_htt, 0, "Steals work from another hyper-threaded core on idle"); 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"); #endif /* ps compat. All cpu percentages from ULE are weighted. */ static int ccpu = 0; SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");