1 /* $NetBSD: kern_idle.c,v 1.9 2007/11/15 20:12:25 ad Exp $ */ 2 3 /*- 4 * Copyright (c)2002, 2006, 2007 YAMAMOTO Takashi, 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 31 __KERNEL_RCSID(0, "$NetBSD: kern_idle.c,v 1.9 2007/11/15 20:12:25 ad Exp $"); 32 33 #include <sys/param.h> 34 #include <sys/cpu.h> 35 #include <sys/idle.h> 36 #include <sys/kthread.h> 37 #include <sys/lockdebug.h> 38 #include <sys/kmem.h> 39 #include <sys/proc.h> 40 41 #include <uvm/uvm.h> 42 #include <uvm/uvm_extern.h> 43 44 void 45 idle_loop(void *dummy) 46 { 47 struct cpu_info *ci = curcpu(); 48 struct lwp *l = curlwp; 49 50 /* Update start time for this thread. */ 51 lwp_lock(l); 52 microtime(&l->l_stime); 53 lwp_unlock(l); 54 55 KERNEL_UNLOCK_ALL(l, NULL); 56 l->l_stat = LSONPROC; 57 while (1 /* CONSTCOND */) { 58 LOCKDEBUG_BARRIER(NULL, 0); 59 KASSERT((l->l_flag & LW_IDLE) != 0); 60 KASSERT(ci == curcpu()); 61 KASSERT(l == curlwp); 62 KASSERT(CURCPU_IDLE_P()); 63 KASSERT(l->l_priority == PRI_IDLE); 64 65 if (uvm.page_idle_zero) { 66 if (sched_curcpu_runnable_p()) { 67 goto schedule; 68 } 69 uvm_pageidlezero(); 70 } 71 if (!sched_curcpu_runnable_p()) { 72 cpu_idle(); 73 if (!sched_curcpu_runnable_p() && 74 !ci->ci_want_resched) { 75 continue; 76 } 77 } 78 schedule: 79 KASSERT(l->l_mutex == &l->l_cpu->ci_schedstate.spc_lwplock); 80 lwp_lock(l); 81 mi_switch(l); 82 KASSERT(curlwp == l); 83 KASSERT(l->l_stat == LSONPROC); 84 } 85 } 86 87 int 88 create_idle_lwp(struct cpu_info *ci) 89 { 90 lwp_t *l; 91 int error; 92 93 KASSERT(ci->ci_data.cpu_idlelwp == NULL); 94 error = kthread_create(PRI_IDLE, KTHREAD_MPSAFE | KTHREAD_IDLE, 95 ci, idle_loop, NULL, &l, "idle/%d", (int)ci->ci_cpuid); 96 if (error != 0) 97 panic("create_idle_lwp: error %d", error); 98 lwp_lock(l); 99 l->l_flag |= LW_IDLE; 100 lwp_unlock(l); 101 l->l_cpu = ci; 102 ci->ci_data.cpu_idlelwp = l; 103 104 return error; 105 } 106