1 /* $NetBSD: kern_idle.c,v 1.7 2007/11/06 00:42:41 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 1.7 2007/11/06 00:42:41 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 microtime(&l->l_stime); 52 53 KERNEL_UNLOCK_ALL(l, NULL); 54 l->l_stat = LSONPROC; 55 while (1 /* CONSTCOND */) { 56 KERNEL_LOCK_ASSERT_UNLOCKED(); 57 LOCKDEBUG_BARRIER(NULL, 0); 58 KASSERT((l->l_flag & LW_IDLE) != 0); 59 KASSERT(ci == curcpu()); 60 KASSERT(l == curlwp); 61 KASSERT(CURCPU_IDLE_P()); 62 KASSERT(l->l_priority == PRI_IDLE); 63 64 if (uvm.page_idle_zero) { 65 if (sched_curcpu_runnable_p()) { 66 goto schedule; 67 } 68 uvm_pageidlezero(); 69 } 70 if (!sched_curcpu_runnable_p()) { 71 cpu_idle(); 72 if (!sched_curcpu_runnable_p() && 73 !ci->ci_want_resched) { 74 continue; 75 } 76 } 77 schedule: 78 KASSERT(l->l_mutex == &l->l_cpu->ci_schedstate.spc_lwplock); 79 lwp_lock(l); 80 mi_switch(l); 81 KASSERT(curlwp == l); 82 KASSERT(l->l_stat == LSONPROC); 83 } 84 } 85 86 int 87 create_idle_lwp(struct cpu_info *ci) 88 { 89 lwp_t *l; 90 int error; 91 92 KASSERT(ci->ci_data.cpu_idlelwp == NULL); 93 error = kthread_create(PRI_IDLE, KTHREAD_MPSAFE | KTHREAD_IDLE, 94 ci, idle_loop, NULL, &l, "idle/%d", (int)ci->ci_cpuid); 95 if (error != 0) 96 panic("create_idle_lwp: error %d", error); 97 lwp_lock(l); 98 l->l_flag |= LW_IDLE; 99 lwp_unlock(l); 100 l->l_cpu = ci; 101 ci->ci_data.cpu_idlelwp = l; 102 103 return error; 104 } 105