132 lines
3.8 KiB
C
132 lines
3.8 KiB
C
/* $NetBSD: kern_idle.c,v 1.36 2024/03/01 04:32:38 mrg Exp $ */
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/*-
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* Copyright (c)2002, 2006, 2007 YAMAMOTO Takashi,
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: kern_idle.c,v 1.36 2024/03/01 04:32:38 mrg Exp $");
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#include <sys/param.h>
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#include <sys/cpu.h>
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#include <sys/idle.h>
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#include <sys/kthread.h>
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#include <sys/lockdebug.h>
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#include <sys/kmem.h>
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#include <sys/proc.h>
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#include <sys/atomic.h>
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#include <uvm/uvm.h> /* uvm_idle */
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void
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idle_loop(void *dummy)
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{
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struct cpu_info *ci = curcpu();
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struct schedstate_percpu *spc;
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struct lwp *l = curlwp;
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KASSERT(l->l_blcnt == 0);
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lwp_lock(l);
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spc = &ci->ci_schedstate;
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KASSERT(lwp_locked(l, spc->spc_lwplock));
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kcpuset_atomic_set(kcpuset_running, cpu_index(ci));
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/* Update start time for this thread. */
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binuptime(&l->l_stime);
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spc->spc_flags |= SPCF_RUNNING;
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KASSERT((l->l_pflag & LP_RUNNING) != 0);
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l->l_stat = LSIDL;
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lwp_unlock(l);
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/*
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* Use spl0() here to ensure that we have the correct interrupt
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* priority. This may be the first thread running on the CPU,
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* in which case we took an odd route to get here.
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*/
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spl0();
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for (;;) {
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LOCKDEBUG_BARRIER(NULL, 0);
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KASSERT((l->l_flag & LW_IDLE) != 0);
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KASSERT(ci == curcpu());
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KASSERT(l == curlwp);
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KASSERT(CURCPU_IDLE_P());
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KASSERT(l->l_priority == PRI_IDLE);
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KASSERTMSG(l->l_nopreempt == 0, "lwp %p nopreempt %d",
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l, l->l_nopreempt);
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sched_idle();
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if (!sched_curcpu_runnable_p()) {
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if ((spc->spc_flags & SPCF_OFFLINE) == 0) {
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uvm_idle();
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}
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if (!sched_curcpu_runnable_p()) {
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cpu_idle();
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if (!sched_curcpu_runnable_p() &&
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!ci->ci_want_resched) {
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continue;
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}
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}
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}
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KASSERT(l->l_mutex == l->l_cpu->ci_schedstate.spc_lwplock);
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lwp_lock(l);
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spc_lock(l->l_cpu);
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mi_switch(l);
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KASSERT(curlwp == l);
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KASSERT(l->l_stat == LSIDL);
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}
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}
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int
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create_idle_lwp(struct cpu_info *ci)
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{
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lwp_t *l;
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int error;
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KASSERT(ci->ci_data.cpu_idlelwp == NULL);
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error = kthread_create(PRI_IDLE, KTHREAD_MPSAFE | KTHREAD_IDLE,
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ci, idle_loop, NULL, &l, "idle/%u", ci->ci_index);
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if (error != 0)
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panic("create_idle_lwp: error %d", error);
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lwp_lock(l);
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l->l_flag |= LW_IDLE;
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if (ci != lwp0.l_cpu) {
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/*
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* For secondary CPUs, the idle LWP is the first to run, and
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* it's directly entered from MD code without a trip through
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* mi_switch(). Make the picture look good in case the CPU
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* takes an interrupt before it calls idle_loop().
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*/
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l->l_stat = LSIDL;
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l->l_pflag |= LP_RUNNING;
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ci->ci_onproc = l;
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}
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lwp_unlock(l);
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ci->ci_data.cpu_idlelwp = l;
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return error;
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}
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