/* $NetBSD: kern_idle.c,v 1.34.20.1 2024/09/11 10:09:19 martin Exp $ */ /*- * Copyright (c)2002, 2006, 2007 YAMAMOTO Takashi, * 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, 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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. */ #include __KERNEL_RCSID(0, "$NetBSD: kern_idle.c,v 1.34.20.1 2024/09/11 10:09:19 martin Exp $"); #include #include #include #include #include #include #include #include #include /* uvm_idle */ void idle_loop(void *dummy) { struct cpu_info *ci = curcpu(); struct schedstate_percpu *spc; struct lwp *l = curlwp; lwp_lock(l); spc = &ci->ci_schedstate; KASSERT(lwp_locked(l, spc->spc_lwplock)); kcpuset_atomic_set(kcpuset_running, cpu_index(ci)); /* Update start time for this thread. */ binuptime(&l->l_stime); spc->spc_flags |= SPCF_RUNNING; KASSERT((l->l_pflag & LP_RUNNING) != 0); l->l_stat = LSIDL; lwp_unlock(l); /* * Use spl0() here to ensure that we have the correct interrupt * priority. This may be the first thread running on the CPU, * in which case we took an odd route to get here. */ spl0(); KERNEL_UNLOCK_ALL(l, NULL); for (;;) { LOCKDEBUG_BARRIER(NULL, 0); KASSERT((l->l_flag & LW_IDLE) != 0); KASSERT(ci == curcpu()); KASSERT(l == curlwp); KASSERT(CURCPU_IDLE_P()); KASSERT(l->l_priority == PRI_IDLE); KASSERTMSG(l->l_nopreempt == 0, "lwp %p nopreempt %d", l, l->l_nopreempt); sched_idle(); if (!sched_curcpu_runnable_p()) { if ((spc->spc_flags & SPCF_OFFLINE) == 0) { uvm_idle(); } if (!sched_curcpu_runnable_p()) { cpu_idle(); if (!sched_curcpu_runnable_p() && !ci->ci_want_resched) { continue; } } } KASSERT(l->l_mutex == l->l_cpu->ci_schedstate.spc_lwplock); lwp_lock(l); spc_lock(l->l_cpu); mi_switch(l); KASSERT(curlwp == l); KASSERT(l->l_stat == LSIDL); } } int create_idle_lwp(struct cpu_info *ci) { lwp_t *l; int error; KASSERT(ci->ci_data.cpu_idlelwp == NULL); error = kthread_create(PRI_IDLE, KTHREAD_MPSAFE | KTHREAD_IDLE, ci, idle_loop, NULL, &l, "idle/%u", ci->ci_index); if (error != 0) panic("create_idle_lwp: error %d", error); lwp_lock(l); l->l_flag |= LW_IDLE; if (ci != lwp0.l_cpu) { /* * For secondary CPUs, the idle LWP is the first to run, and * it's directly entered from MD code without a trip through * mi_switch(). Make the picture look good in case the CPU * takes an interrupt before it calls idle_loop(). */ l->l_stat = LSIDL; l->l_pflag |= LP_RUNNING; ci->ci_onproc = l; } lwp_unlock(l); ci->ci_data.cpu_idlelwp = l; return error; }