Author: jeff Date: Sun Dec 15 21:11:15 2019 New Revision: 355779 URL: https://svnweb.freebsd.org/changeset/base/355779
Log: schedlock 1/4 Eliminate recursion from most thread_lock consumers. Return from sched_add() without the thread_lock held. This eliminates unnecessary atomics and lock word loads as well as reducing the hold time for scheduler locks. This will eventually allow for lockless remote adds. Discussed with: kib Reviewed by: jhb Tested by: pho Differential Revision: https://reviews.freebsd.org/D22626 Modified: head/sys/cddl/compat/opensolaris/sys/proc.h head/sys/compat/linux/linux_fork.c head/sys/compat/linuxkpi/common/src/linux_kthread.c head/sys/dev/ocs_fc/ocs_os.c head/sys/kern/init_main.c head/sys/kern/kern_clock.c head/sys/kern/kern_fork.c head/sys/kern/kern_intr.c head/sys/kern/kern_kthread.c head/sys/kern/kern_mutex.c head/sys/kern/kern_resource.c head/sys/kern/kern_sig.c head/sys/kern/kern_synch.c head/sys/kern/kern_thr.c head/sys/kern/kern_thread.c head/sys/kern/sched_4bsd.c head/sys/kern/sched_ule.c head/sys/kern/subr_gtaskqueue.c head/sys/kern/subr_pcpu.c head/sys/kern/subr_sleepqueue.c head/sys/kern/subr_taskqueue.c head/sys/kern/subr_turnstile.c head/sys/mips/nlm/cms.c head/sys/sys/proc.h head/sys/sys/resourcevar.h head/sys/sys/sched.h head/sys/vm/vm_swapout.c Modified: head/sys/cddl/compat/opensolaris/sys/proc.h ============================================================================== --- head/sys/cddl/compat/opensolaris/sys/proc.h Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/cddl/compat/opensolaris/sys/proc.h Sun Dec 15 21:11:15 2019 (r355779) @@ -89,7 +89,6 @@ do_thread_create(caddr_t stk, size_t stksize, void (*p thread_lock(td); sched_prio(td, pri); sched_add(td, SRQ_BORING); - thread_unlock(td); } return (td); } Modified: head/sys/compat/linux/linux_fork.c ============================================================================== --- head/sys/compat/linux/linux_fork.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/compat/linux/linux_fork.c Sun Dec 15 21:11:15 2019 (r355779) @@ -92,7 +92,6 @@ linux_fork(struct thread *td, struct linux_fork_args * thread_lock(td2); TD_SET_CAN_RUN(td2); sched_add(td2, SRQ_BORING); - thread_unlock(td2); return (0); } @@ -123,7 +122,6 @@ linux_vfork(struct thread *td, struct linux_vfork_args thread_lock(td2); TD_SET_CAN_RUN(td2); sched_add(td2, SRQ_BORING); - thread_unlock(td2); return (0); } @@ -228,7 +226,6 @@ linux_clone_proc(struct thread *td, struct linux_clone thread_lock(td2); TD_SET_CAN_RUN(td2); sched_add(td2, SRQ_BORING); - thread_unlock(td2); td->td_retval[0] = p2->p_pid; @@ -343,7 +340,6 @@ linux_clone_thread(struct thread *td, struct linux_clo thread_lock(newtd); TD_SET_CAN_RUN(newtd); sched_add(newtd, SRQ_BORING); - thread_unlock(newtd); td->td_retval[0] = newtd->td_tid; Modified: head/sys/compat/linuxkpi/common/src/linux_kthread.c ============================================================================== --- head/sys/compat/linuxkpi/common/src/linux_kthread.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/compat/linuxkpi/common/src/linux_kthread.c Sun Dec 15 21:11:15 2019 (r355779) @@ -142,7 +142,6 @@ linux_kthread_setup_and_run(struct thread *td, linux_t sched_prio(td, PI_SWI(SWI_NET)); /* put thread into run-queue */ sched_add(td, SRQ_BORING); - thread_unlock(td); return (task); } Modified: head/sys/dev/ocs_fc/ocs_os.c ============================================================================== --- head/sys/dev/ocs_fc/ocs_os.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/dev/ocs_fc/ocs_os.c Sun Dec 15 21:11:15 2019 (r355779) @@ -659,6 +659,8 @@ ocs_thread_create(ocs_os_handle_t os, ocs_thread_t *th int32_t ocs_thread_start(ocs_thread_t *thread) { + + thread_lock(thread->tcb); sched_add(thread->tcb, SRQ_BORING); return 0; } Modified: head/sys/kern/init_main.c ============================================================================== --- head/sys/kern/init_main.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/kern/init_main.c Sun Dec 15 21:11:15 2019 (r355779) @@ -853,6 +853,5 @@ kick_init(const void *udata __unused) thread_lock(td); TD_SET_CAN_RUN(td); sched_add(td, SRQ_BORING); - thread_unlock(td); } SYSINIT(kickinit, SI_SUB_KTHREAD_INIT, SI_ORDER_MIDDLE, kick_init, NULL); Modified: head/sys/kern/kern_clock.c ============================================================================== --- head/sys/kern/kern_clock.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/kern/kern_clock.c Sun Dec 15 21:11:15 2019 (r355779) @@ -282,8 +282,7 @@ deadlkres(void) if (TD_ON_LOCK(td)) deadlres_td_on_lock(p, td, blkticks); - else if (TD_IS_SLEEPING(td) && - TD_ON_SLEEPQ(td)) + else if (TD_IS_SLEEPING(td)) deadlres_td_sleep_q(p, td, slpticks); thread_unlock(td); Modified: head/sys/kern/kern_fork.c ============================================================================== --- head/sys/kern/kern_fork.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/kern/kern_fork.c Sun Dec 15 21:11:15 2019 (r355779) @@ -758,7 +758,6 @@ do_fork(struct thread *td, struct fork_req *fr, struct thread_lock(td2); TD_SET_CAN_RUN(td2); sched_add(td2, SRQ_BORING); - thread_unlock(td2); } else { *fr->fr_procp = p2; } Modified: head/sys/kern/kern_intr.c ============================================================================== --- head/sys/kern/kern_intr.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/kern/kern_intr.c Sun Dec 15 21:11:15 2019 (r355779) @@ -558,8 +558,8 @@ ithread_destroy(struct intr_thread *ithread) if (TD_AWAITING_INTR(td)) { TD_CLR_IWAIT(td); sched_add(td, SRQ_INTR); - } - thread_unlock(td); + } else + thread_unlock(td); } int @@ -985,8 +985,8 @@ intr_event_schedule_thread(struct intr_event *ie) } else { CTR5(KTR_INTR, "%s: pid %d (%s): it_need %d, state %d", __func__, td->td_proc->p_pid, td->td_name, it->it_need, td->td_state); + thread_unlock(td); } - thread_unlock(td); return (0); } Modified: head/sys/kern/kern_kthread.c ============================================================================== --- head/sys/kern/kern_kthread.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/kern/kern_kthread.c Sun Dec 15 21:11:15 2019 (r355779) @@ -146,7 +146,8 @@ kproc_create(void (*func)(void *), void *arg, /* Delay putting it on the run queue until now. */ if (!(flags & RFSTOPPED)) sched_add(td, SRQ_BORING); - thread_unlock(td); + else + thread_unlock(td); return 0; } @@ -324,7 +325,6 @@ kthread_add(void (*func)(void *), void *arg, struct pr if (!(flags & RFSTOPPED)) { thread_lock(newtd); sched_add(newtd, SRQ_BORING); - thread_unlock(newtd); } if (newtdp) *newtdp = newtd; Modified: head/sys/kern/kern_mutex.c ============================================================================== --- head/sys/kern/kern_mutex.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/kern/kern_mutex.c Sun Dec 15 21:11:15 2019 (r355779) @@ -960,10 +960,9 @@ thread_lock_block(struct thread *td) { struct mtx *lock; - THREAD_LOCK_ASSERT(td, MA_OWNED); lock = td->td_lock; + mtx_assert(lock, MA_OWNED); td->td_lock = &blocked_lock; - mtx_unlock_spin(lock); return (lock); } @@ -971,19 +970,33 @@ thread_lock_block(struct thread *td) void thread_lock_unblock(struct thread *td, struct mtx *new) { + mtx_assert(new, MA_OWNED); - MPASS(td->td_lock == &blocked_lock); + KASSERT(td->td_lock == &blocked_lock, + ("thread %p lock %p not blocked_lock %p", + td, td->td_lock, &blocked_lock)); atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); } void +thread_lock_block_wait(struct thread *td) +{ + + while (td->td_lock == &blocked_lock) + cpu_spinwait(); + + /* Acquire fence to be certain that all thread state is visible. */ + atomic_thread_fence_acq(); +} + +void thread_lock_set(struct thread *td, struct mtx *new) { struct mtx *lock; mtx_assert(new, MA_OWNED); - THREAD_LOCK_ASSERT(td, MA_OWNED); lock = td->td_lock; + mtx_assert(lock, MA_OWNED); td->td_lock = new; mtx_unlock_spin(lock); } Modified: head/sys/kern/kern_resource.c ============================================================================== --- head/sys/kern/kern_resource.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/kern/kern_resource.c Sun Dec 15 21:11:15 2019 (r355779) @@ -78,7 +78,7 @@ static void calcru1(struct proc *p, struct rusage_ext struct timeval *up, struct timeval *sp); static int donice(struct thread *td, struct proc *chgp, int n); static struct uidinfo *uilookup(uid_t uid); -static void ruxagg_locked(struct rusage_ext *rux, struct thread *td); +static void ruxagg_ext_locked(struct rusage_ext *rux, struct thread *td); /* * Resource controls and accounting. @@ -858,7 +858,7 @@ rufetchtd(struct thread *td, struct rusage *ru) td->td_incruntime += runtime; PCPU_SET(switchtime, u); } - ruxagg(p, td); + ruxagg_locked(p, td); *ru = td->td_ru; calcru1(p, &td->td_rux, &ru->ru_utime, &ru->ru_stime); } @@ -1114,11 +1114,9 @@ ruadd(struct rusage *ru, struct rusage_ext *rux, struc * Aggregate tick counts into the proc's rusage_ext. */ static void -ruxagg_locked(struct rusage_ext *rux, struct thread *td) +ruxagg_ext_locked(struct rusage_ext *rux, struct thread *td) { - THREAD_LOCK_ASSERT(td, MA_OWNED); - PROC_STATLOCK_ASSERT(td->td_proc, MA_OWNED); rux->rux_runtime += td->td_incruntime; rux->rux_uticks += td->td_uticks; rux->rux_sticks += td->td_sticks; @@ -1126,16 +1124,25 @@ ruxagg_locked(struct rusage_ext *rux, struct thread *t } void -ruxagg(struct proc *p, struct thread *td) +ruxagg_locked(struct proc *p, struct thread *td) { + THREAD_LOCK_ASSERT(td, MA_OWNED); + PROC_STATLOCK_ASSERT(td->td_proc, MA_OWNED); - thread_lock(td); - ruxagg_locked(&p->p_rux, td); - ruxagg_locked(&td->td_rux, td); + ruxagg_ext_locked(&p->p_rux, td); + ruxagg_ext_locked(&td->td_rux, td); td->td_incruntime = 0; td->td_uticks = 0; td->td_iticks = 0; td->td_sticks = 0; +} + +void +ruxagg(struct proc *p, struct thread *td) +{ + + thread_lock(td); + ruxagg_locked(p, td); thread_unlock(td); } Modified: head/sys/kern/kern_sig.c ============================================================================== --- head/sys/kern/kern_sig.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/kern/kern_sig.c Sun Dec 15 21:11:15 2019 (r355779) @@ -2250,6 +2250,8 @@ tdsendsignal(struct proc *p, struct thread *td, int si p->p_step = 0; wakeup(&p->p_step); } + wakeup_swapper = 0; + /* * Some signals have a process-wide effect and a per-thread * component. Most processing occurs when the process next @@ -2352,15 +2354,13 @@ tdsendsignal(struct proc *p, struct thread *td, int si * the PROCESS runnable, leave it stopped. * It may run a bit until it hits a thread_suspend_check(). */ - wakeup_swapper = 0; PROC_SLOCK(p); thread_lock(td); - if (TD_ON_SLEEPQ(td) && (td->td_flags & TDF_SINTR)) + if (TD_CAN_ABORT(td)) wakeup_swapper = sleepq_abort(td, intrval); - thread_unlock(td); + else + thread_unlock(td); PROC_SUNLOCK(p); - if (wakeup_swapper) - kick_proc0(); goto out; /* * Mutexes are short lived. Threads waiting on them will @@ -2394,8 +2394,6 @@ tdsendsignal(struct proc *p, struct thread *td, int si sigqueue_delete_proc(p, p->p_xsig); } else PROC_SUNLOCK(p); - if (wakeup_swapper) - kick_proc0(); goto out; } } else { @@ -2416,6 +2414,9 @@ runfast: out: /* If we jump here, proc slock should not be owned. */ PROC_SLOCK_ASSERT(p, MA_NOTOWNED); + if (wakeup_swapper) + kick_proc0(); + return (ret); } @@ -2428,10 +2429,8 @@ static void tdsigwakeup(struct thread *td, int sig, sig_t action, int intrval) { struct proc *p = td->td_proc; - int prop; - int wakeup_swapper; + int prop, wakeup_swapper; - wakeup_swapper = 0; PROC_LOCK_ASSERT(p, MA_OWNED); prop = sigprop(sig); @@ -2487,22 +2486,25 @@ tdsigwakeup(struct thread *td, int sig, sig_t action, sched_prio(td, PUSER); wakeup_swapper = sleepq_abort(td, intrval); - } else { - /* - * Other states do nothing with the signal immediately, - * other than kicking ourselves if we are running. - * It will either never be noticed, or noticed very soon. - */ + PROC_SUNLOCK(p); + if (wakeup_swapper) + kick_proc0(); + return; + } + + /* + * Other states do nothing with the signal immediately, + * other than kicking ourselves if we are running. + * It will either never be noticed, or noticed very soon. + */ #ifdef SMP - if (TD_IS_RUNNING(td) && td != curthread) - forward_signal(td); + if (TD_IS_RUNNING(td) && td != curthread) + forward_signal(td); #endif - } + out: PROC_SUNLOCK(p); thread_unlock(td); - if (wakeup_swapper) - kick_proc0(); } static int @@ -2530,12 +2532,13 @@ sig_suspend_threads(struct thread *td, struct proc *p, */ KASSERT(!TD_IS_SUSPENDED(td2), ("thread with deferred stops suspended")); - if (TD_SBDRY_INTR(td2)) + if (TD_SBDRY_INTR(td2)) { wakeup_swapper |= sleepq_abort(td2, TD_SBDRY_ERRNO(td2)); - } else if (!TD_IS_SUSPENDED(td2)) { + continue; + } + } else if (!TD_IS_SUSPENDED(td2)) thread_suspend_one(td2); - } } else if (!TD_IS_SUSPENDED(td2)) { if (sending || td != td2) td2->td_flags |= TDF_ASTPENDING; Modified: head/sys/kern/kern_synch.c ============================================================================== --- head/sys/kern/kern_synch.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/kern/kern_synch.c Sun Dec 15 21:11:15 2019 (r355779) @@ -538,40 +538,48 @@ mi_switch(int flags, struct thread *newtd) * Change thread state to be runnable, placing it on the run queue if * it is in memory. If it is swapped out, return true so our caller * will know to awaken the swapper. + * + * Requires the thread lock on entry, drops on exit. */ int -setrunnable(struct thread *td) +setrunnable(struct thread *td, int srqflags) { + int swapin; THREAD_LOCK_ASSERT(td, MA_OWNED); KASSERT(td->td_proc->p_state != PRS_ZOMBIE, ("setrunnable: pid %d is a zombie", td->td_proc->p_pid)); + + swapin = 0; switch (td->td_state) { case TDS_RUNNING: case TDS_RUNQ: + break; + case TDS_CAN_RUN: + KASSERT((td->td_flags & TDF_INMEM) != 0, + ("setrunnable: td %p not in mem, flags 0x%X inhibit 0x%X", + td, td->td_flags, td->td_inhibitors)); + /* unlocks thread lock according to flags */ + sched_wakeup(td, srqflags); return (0); case TDS_INHIBITED: /* * If we are only inhibited because we are swapped out - * then arange to swap in this process. Otherwise just return. + * arrange to swap in this process. */ - if (td->td_inhibitors != TDI_SWAPPED) - return (0); - /* FALLTHROUGH */ - case TDS_CAN_RUN: + if (td->td_inhibitors == TDI_SWAPPED && + (td->td_flags & TDF_SWAPINREQ) == 0) { + td->td_flags |= TDF_SWAPINREQ; + swapin = 1; + } break; default: - printf("state is 0x%x", td->td_state); - panic("setrunnable(2)"); + panic("setrunnable: state 0x%x", td->td_state); } - if ((td->td_flags & TDF_INMEM) == 0) { - if ((td->td_flags & TDF_SWAPINREQ) == 0) { - td->td_flags |= TDF_SWAPINREQ; - return (1); - } - } else - sched_wakeup(td); - return (0); + if ((srqflags & (SRQ_HOLD | SRQ_HOLDTD)) == 0) + thread_unlock(td); + + return (swapin); } /* Modified: head/sys/kern/kern_thr.c ============================================================================== --- head/sys/kern/kern_thr.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/kern/kern_thr.c Sun Dec 15 21:11:15 2019 (r355779) @@ -281,7 +281,6 @@ thread_create(struct thread *td, struct rtprio *rtp, } TD_SET_CAN_RUN(newtd); sched_add(newtd, SRQ_BORING); - thread_unlock(newtd); return (0); Modified: head/sys/kern/kern_thread.c ============================================================================== --- head/sys/kern/kern_thread.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/kern/kern_thread.c Sun Dec 15 21:11:15 2019 (r355779) @@ -565,7 +565,6 @@ thread_exit(void) thread_lock(p->p_singlethread); wakeup_swapper = thread_unsuspend_one( p->p_singlethread, p, false); - thread_unlock(p->p_singlethread); if (wakeup_swapper) kick_proc0(); } @@ -606,7 +605,7 @@ thread_exit(void) /* Save our resource usage in our process. */ td->td_ru.ru_nvcsw++; - ruxagg(p, td); + ruxagg_locked(p, td); rucollect(&p->p_ru, &td->td_ru); PROC_STATUNLOCK(p); @@ -730,19 +729,36 @@ weed_inhib(int mode, struct thread *td2, struct proc * THREAD_LOCK_ASSERT(td2, MA_OWNED); wakeup_swapper = 0; + + /* + * Since the thread lock is dropped by the scheduler we have + * to retry to check for races. + */ +restart: switch (mode) { case SINGLE_EXIT: - if (TD_IS_SUSPENDED(td2)) + if (TD_IS_SUSPENDED(td2)) { wakeup_swapper |= thread_unsuspend_one(td2, p, true); - if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) + thread_lock(td2); + goto restart; + } + if (TD_CAN_ABORT(td2)) { wakeup_swapper |= sleepq_abort(td2, EINTR); + return (wakeup_swapper); + } break; case SINGLE_BOUNDARY: case SINGLE_NO_EXIT: - if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0) + if (TD_IS_SUSPENDED(td2) && + (td2->td_flags & TDF_BOUNDARY) == 0) { wakeup_swapper |= thread_unsuspend_one(td2, p, false); - if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) + thread_lock(td2); + goto restart; + } + if (TD_CAN_ABORT(td2)) { wakeup_swapper |= sleepq_abort(td2, ERESTART); + return (wakeup_swapper); + } break; case SINGLE_ALLPROC: /* @@ -754,18 +770,25 @@ weed_inhib(int mode, struct thread *td2, struct proc * * is used to avoid immediate un-suspend. */ if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY | - TDF_ALLPROCSUSP)) == 0) + TDF_ALLPROCSUSP)) == 0) { wakeup_swapper |= thread_unsuspend_one(td2, p, false); - if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) { + thread_lock(td2); + goto restart; + } + if (TD_CAN_ABORT(td2)) { if ((td2->td_flags & TDF_SBDRY) == 0) { thread_suspend_one(td2); td2->td_flags |= TDF_ALLPROCSUSP; } else { wakeup_swapper |= sleepq_abort(td2, ERESTART); + return (wakeup_swapper); } } break; + default: + break; } + thread_unlock(td2); return (wakeup_swapper); } @@ -842,9 +865,10 @@ thread_single(struct proc *p, int mode) #ifdef SMP } else if (TD_IS_RUNNING(td2) && td != td2) { forward_signal(td2); + thread_unlock(td2); #endif - } - thread_unlock(td2); + } else + thread_unlock(td2); } if (wakeup_swapper) kick_proc0(); @@ -1028,7 +1052,6 @@ thread_suspend_check(int return_instead) thread_lock(p->p_singlethread); wakeup_swapper = thread_unsuspend_one( p->p_singlethread, p, false); - thread_unlock(p->p_singlethread); if (wakeup_swapper) kick_proc0(); } @@ -1112,7 +1135,7 @@ thread_unsuspend_one(struct thread *td, struct proc *p p->p_boundary_count--; } } - return (setrunnable(td)); + return (setrunnable(td, 0)); } /* @@ -1133,8 +1156,8 @@ thread_unsuspend(struct proc *p) if (TD_IS_SUSPENDED(td)) { wakeup_swapper |= thread_unsuspend_one(td, p, true); - } - thread_unlock(td); + } else + thread_unlock(td); } } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && p->p_numthreads == p->p_suspcount) { @@ -1147,7 +1170,6 @@ thread_unsuspend(struct proc *p) thread_lock(p->p_singlethread); wakeup_swapper = thread_unsuspend_one( p->p_singlethread, p, false); - thread_unlock(p->p_singlethread); } } if (wakeup_swapper) @@ -1193,8 +1215,8 @@ thread_single_end(struct proc *p, int mode) if (TD_IS_SUSPENDED(td)) { wakeup_swapper |= thread_unsuspend_one(td, p, mode == SINGLE_BOUNDARY); - } - thread_unlock(td); + } else + thread_unlock(td); } } KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0, Modified: head/sys/kern/sched_4bsd.c ============================================================================== --- head/sys/kern/sched_4bsd.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/kern/sched_4bsd.c Sun Dec 15 21:11:15 2019 (r355779) @@ -846,7 +846,7 @@ sched_priority(struct thread *td, u_char prio) td->td_priority = prio; if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) { sched_rem(td); - sched_add(td, SRQ_BORING); + sched_add(td, SRQ_BORING | SRQ_HOLDTD); } } @@ -980,25 +980,12 @@ sched_switch(struct thread *td, struct thread *newtd, struct proc *p; int preempted; - tmtx = NULL; + tmtx = &sched_lock; ts = td_get_sched(td); p = td->td_proc; THREAD_LOCK_ASSERT(td, MA_OWNED); - /* - * Switch to the sched lock to fix things up and pick - * a new thread. - * Block the td_lock in order to avoid breaking the critical path. - */ - if (td->td_lock != &sched_lock) { - mtx_lock_spin(&sched_lock); - tmtx = thread_lock_block(td); - } - - if ((td->td_flags & TDF_NOLOAD) == 0) - sched_load_rem(); - td->td_lastcpu = td->td_oncpu; preempted = (td->td_flags & TDF_SLICEEND) == 0 && (flags & SW_PREEMPT) != 0; @@ -1021,10 +1008,25 @@ sched_switch(struct thread *td, struct thread *newtd, if (TD_IS_RUNNING(td)) { /* Put us back on the run queue. */ sched_add(td, preempted ? - SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : - SRQ_OURSELF|SRQ_YIELDING); + SRQ_HOLDTD|SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : + SRQ_HOLDTD|SRQ_OURSELF|SRQ_YIELDING); } } + + /* + * Switch to the sched lock to fix things up and pick + * a new thread. Block the td_lock in order to avoid + * breaking the critical path. + */ + if (td->td_lock != &sched_lock) { + mtx_lock_spin(&sched_lock); + tmtx = thread_lock_block(td); + mtx_unlock_spin(tmtx); + } + + if ((td->td_flags & TDF_NOLOAD) == 0) + sched_load_rem(); + if (newtd) { /* * The thread we are about to run needs to be counted @@ -1042,9 +1044,10 @@ sched_switch(struct thread *td, struct thread *newtd, sched_load_add(); } else { newtd = choosethread(); - MPASS(newtd->td_lock == &sched_lock); } + MPASS(newtd->td_lock == &sched_lock); + #if (KTR_COMPILE & KTR_SCHED) != 0 if (TD_IS_IDLETHREAD(td)) KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle", @@ -1075,7 +1078,7 @@ sched_switch(struct thread *td, struct thread *newtd, (*dtrace_vtime_switch_func)(newtd); #endif - cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock); + cpu_switch(td, newtd, tmtx); lock_profile_obtain_lock_success(&sched_lock.lock_object, 0, 0, __FILE__, __LINE__); /* @@ -1100,8 +1103,10 @@ sched_switch(struct thread *td, struct thread *newtd, if (PMC_PROC_IS_USING_PMCS(td->td_proc)) PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); #endif - } else + } else { + td->td_lock = &sched_lock; SDT_PROBE0(sched, , , remain__cpu); + } KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", "prio:%d", td->td_priority); @@ -1116,7 +1121,7 @@ sched_switch(struct thread *td, struct thread *newtd, } void -sched_wakeup(struct thread *td) +sched_wakeup(struct thread *td, int srqflags) { struct td_sched *ts; @@ -1130,7 +1135,7 @@ sched_wakeup(struct thread *td) td->td_slptick = 0; ts->ts_slptime = 0; ts->ts_slice = sched_slice; - sched_add(td, SRQ_BORING); + sched_add(td, srqflags); } #ifdef SMP @@ -1316,7 +1321,11 @@ sched_add(struct thread *td, int flags) */ if (td->td_lock != &sched_lock) { mtx_lock_spin(&sched_lock); - thread_lock_set(td, &sched_lock); + if ((flags & SRQ_HOLD) != 0) + td->td_lock = &sched_lock; + else + thread_lock_set(td, &sched_lock); + } TD_SET_RUNQ(td); @@ -1380,6 +1389,8 @@ sched_add(struct thread *td, int flags) maybe_resched(td); } } + if ((flags & SRQ_HOLDTD) == 0) + thread_unlock(td); } #else /* SMP */ { @@ -1407,7 +1418,10 @@ sched_add(struct thread *td, int flags) */ if (td->td_lock != &sched_lock) { mtx_lock_spin(&sched_lock); - thread_lock_set(td, &sched_lock); + if ((flags & SRQ_HOLD) != 0) + td->td_lock = &sched_lock; + else + thread_lock_set(td, &sched_lock); } TD_SET_RUNQ(td); CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); @@ -1418,6 +1432,8 @@ sched_add(struct thread *td, int flags) runq_add(ts->ts_runq, td, flags); if (!maybe_preempt(td)) maybe_resched(td); + if ((flags & SRQ_HOLDTD) == 0) + thread_unlock(td); } #endif /* SMP */ @@ -1776,7 +1792,7 @@ sched_affinity(struct thread *td) /* Put this thread on a valid per-CPU runqueue. */ sched_rem(td); - sched_add(td, SRQ_BORING); + sched_add(td, SRQ_HOLDTD | SRQ_BORING); break; case TDS_RUNNING: /* Modified: head/sys/kern/sched_ule.c ============================================================================== --- head/sys/kern/sched_ule.c Sun Dec 15 21:08:40 2019 (r355778) +++ head/sys/kern/sched_ule.c Sun Dec 15 21:11:15 2019 (r355779) @@ -464,7 +464,7 @@ tdq_runq_add(struct tdq *tdq, struct thread *td, int f u_char pri; TDQ_LOCK_ASSERT(tdq, MA_OWNED); - THREAD_LOCK_ASSERT(td, MA_OWNED); + THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); pri = td->td_priority; ts = td_get_sched(td); @@ -515,6 +515,7 @@ tdq_runq_rem(struct tdq *tdq, struct thread *td) ts = td_get_sched(td); TDQ_LOCK_ASSERT(tdq, MA_OWNED); + THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); KASSERT(ts->ts_runq != NULL, ("tdq_runq_remove: thread %p null ts_runq", td)); if (ts->ts_flags & TSF_XFERABLE) { @@ -539,7 +540,7 @@ tdq_load_add(struct tdq *tdq, struct thread *td) { TDQ_LOCK_ASSERT(tdq, MA_OWNED); - THREAD_LOCK_ASSERT(td, MA_OWNED); + THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); tdq->tdq_load++; if ((td->td_flags & TDF_NOLOAD) == 0) @@ -556,8 +557,8 @@ static void tdq_load_rem(struct tdq *tdq, struct thread *td) { - THREAD_LOCK_ASSERT(td, MA_OWNED); TDQ_LOCK_ASSERT(tdq, MA_OWNED); + THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); KASSERT(tdq->tdq_load != 0, ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); @@ -949,7 +950,6 @@ sched_balance_pair(struct tdq *high, struct tdq *low) static struct thread * tdq_move(struct tdq *from, struct tdq *to) { - struct td_sched *ts; struct thread *td; struct tdq *tdq; int cpu; @@ -962,18 +962,18 @@ tdq_move(struct tdq *from, struct tdq *to) td = tdq_steal(tdq, cpu); if (td == NULL) return (NULL); - ts = td_get_sched(td); + /* - * Although the run queue is locked the thread may be blocked. Lock - * it to clear this and acquire the run-queue lock. + * Although the run queue is locked the thread may be + * blocked. We can not set the lock until it is unblocked. */ - thread_lock(td); - /* Drop recursive lock on from acquired via thread_lock(). */ - TDQ_UNLOCK(from); + thread_lock_block_wait(td); sched_rem(td); - ts->ts_cpu = cpu; + THREAD_LOCKPTR_ASSERT(td, TDQ_LOCKPTR(from)); td->td_lock = TDQ_LOCKPTR(to); + td_get_sched(td)->ts_cpu = cpu; tdq_add(to, td, SRQ_YIELDING); + return (td); } @@ -1205,6 +1205,7 @@ sched_setcpu(struct thread *td, int cpu, int flags) { struct tdq *tdq; + struct mtx *mtx; THREAD_LOCK_ASSERT(td, MA_OWNED); tdq = TDQ_CPU(cpu); @@ -1212,26 +1213,20 @@ sched_setcpu(struct thread *td, int cpu, int flags) /* * If the lock matches just return the queue. */ - if (td->td_lock == TDQ_LOCKPTR(tdq)) + if (td->td_lock == TDQ_LOCKPTR(tdq)) { + KASSERT((flags & SRQ_HOLD) == 0, + ("sched_setcpu: Invalid lock for SRQ_HOLD")); 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); + mtx = thread_lock_block(td); + if ((flags & SRQ_HOLD) == 0) + mtx_unlock_spin(mtx); TDQ_LOCK(tdq); thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); spinlock_exit(); @@ -1422,8 +1417,7 @@ tdq_setup(struct tdq *tdq, int id) tdq->tdq_id = id; 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); + mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", MTX_SPIN); #ifdef KTR snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), "CPU %d load", (int)TDQ_ID(tdq)); @@ -1785,7 +1779,7 @@ sched_thread_priority(struct thread *td, u_char prio) if (TD_ON_RUNQ(td) && prio < td->td_priority) { sched_rem(td); td->td_priority = prio; - sched_add(td, SRQ_BORROWING); + sched_add(td, SRQ_BORROWING | SRQ_HOLDTD); return; } /* @@ -2011,6 +2005,7 @@ static struct mtx * sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) { struct tdq *tdn; + struct mtx *mtx; KASSERT(!CPU_ABSENT(td_get_sched(td)->ts_cpu), ("sched_switch_migrate: " "thread %s queued on absent CPU %d.", td->td_name, @@ -2024,7 +2019,8 @@ sched_switch_migrate(struct tdq *tdq, struct thread *t * not holding either run-queue lock. */ spinlock_enter(); - thread_lock_block(td); /* This releases the lock on tdq. */ + mtx = thread_lock_block(td); + mtx_unlock_spin(mtx); /* * Acquire both run-queue locks before placing the thread on the new @@ -2044,8 +2040,7 @@ sched_switch_migrate(struct tdq *tdq, struct thread *t } /* - * Variadic version of thread_lock_unblock() that does not assume td_lock - * is blocked. + * thread_lock_unblock() that does not assume td_lock is blocked. */ static inline void thread_unblock_switch(struct thread *td, struct mtx *mtx) @@ -2114,8 +2109,13 @@ sched_switch(struct thread *td, struct thread *newtd, } } else { /* This thread must be going to sleep. */ - TDQ_LOCK(tdq); mtx = thread_lock_block(td); + if (mtx != TDQ_LOCKPTR(tdq)) { + spinlock_enter(); + mtx_unlock_spin(mtx); + TDQ_LOCK(tdq); + spinlock_exit(); + } tdq_load_rem(tdq, td); #ifdef SMP if (tdq->tdq_load == 0) @@ -2237,9 +2237,11 @@ sched_sleep(struct thread *td, int prio) /* * Schedule a thread to resume execution and record how long it voluntarily * slept. We also update the pctcpu, interactivity, and priority. + * + * Requires the thread lock on entry, drops on exit. */ void -sched_wakeup(struct thread *td) +sched_wakeup(struct thread *td, int srqflags) { struct td_sched *ts; int slptick; @@ -2247,6 +2249,7 @@ sched_wakeup(struct thread *td) THREAD_LOCK_ASSERT(td, MA_OWNED); ts = td_get_sched(td); td->td_flags &= ~TDF_CANSWAP; + /* * If we slept for more than a tick update our interactivity and * priority. @@ -2262,7 +2265,7 @@ sched_wakeup(struct thread *td) * Reset the slice value since we slept and advanced the round-robin. */ ts->ts_slice = 0; - sched_add(td, SRQ_BORING); + sched_add(td, SRQ_BORING | srqflags); } /* @@ -2578,6 +2581,7 @@ tdq_add(struct tdq *tdq, struct thread *td, int flags) { TDQ_LOCK_ASSERT(tdq, MA_OWNED); + THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); KASSERT((td->td_inhibitors == 0), ("sched_add: trying to run inhibited thread")); KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), @@ -2594,6 +2598,8 @@ tdq_add(struct tdq *tdq, struct thread *td, int flags) /* * Select the target thread queue and add a thread to it. Request * preemption or IPI a remote processor if required. + * + * Requires the thread lock on entry, drops on exit. */ void sched_add(struct thread *td, int flags) @@ -2625,10 +2631,10 @@ sched_add(struct thread *td, int flags) cpu = sched_pickcpu(td, flags); tdq = sched_setcpu(td, cpu, flags); tdq_add(tdq, td, flags); - if (cpu != PCPU_GET(cpuid)) { + if (cpu != PCPU_GET(cpuid)) tdq_notify(tdq, td); - return; - } + else if (!(flags & SRQ_YIELDING)) + sched_setpreempt(td); #else tdq = TDQ_SELF(); TDQ_LOCK(tdq); @@ -2636,11 +2642,16 @@ sched_add(struct thread *td, int flags) * Now that the thread is moving to the run-queue, set the lock *** DIFF OUTPUT TRUNCATED AT 1000 LINES *** _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
