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kern_idle.c revision 1.6 
      1 /*	$NetBSD: kern_idle.c,v 1.6 2007/10/08 20:06:19 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 1.6 2007/10/08 20:06:19 ad Exp $");
     32 
     33 #include <sys/param.h>
     34 #include <sys/cpu.h>
     35 #include <sys/idle.h>
     36 #include <sys/lwp.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 #define	PIDLELWP	(MAXPRI + 1)	/* lowest priority */
     45 
     46 void
     47 idle_loop(void *dummy)
     48 {
     49 	struct cpu_info *ci = curcpu();
     50 	struct lwp *l = curlwp;
     51 
     52 	/* Update start time for this thread. */
     53 	microtime(&l->l_stime);
     54 
     55 	KERNEL_UNLOCK_ALL(l, NULL);
     56 	l->l_usrpri = PIDLELWP;
     57 	l->l_priority = l->l_usrpri;
     58 	l->l_stat = LSONPROC;
     59 	while (1 /* CONSTCOND */) {
     60 		KERNEL_LOCK_ASSERT_UNLOCKED();
     61 		LOCKDEBUG_BARRIER(NULL, 0);
     62 		KASSERT((l->l_flag & LW_IDLE) != 0);
     63 		KASSERT(ci == curcpu());
     64 		KASSERT(l == curlwp);
     65 		KASSERT(CURCPU_IDLE_P());
     66 		KASSERT(l->l_usrpri == PIDLELWP);
     67 
     68 		if (uvm.page_idle_zero) {
     69 			if (sched_curcpu_runnable_p()) {
     70 				goto schedule;
     71 			}
     72 			uvm_pageidlezero();
     73 		}
     74 		if (!sched_curcpu_runnable_p()) {
     75 			cpu_idle();
     76 			if (!sched_curcpu_runnable_p() &&
     77 			    !ci->ci_want_resched) {
     78 				continue;
     79 			}
     80 		}
     81 schedule:
     82 		KASSERT(l->l_mutex == &l->l_cpu->ci_schedstate.spc_lwplock);
     83 		lwp_lock(l);
     84 		mi_switch(l);
     85 		KASSERT(curlwp == l);
     86 		KASSERT(l->l_stat == LSONPROC);
     87 	}
     88 }
     89 
     90 int
     91 create_idle_lwp(struct cpu_info *ci)
     92 {
     93 	struct proc *p = &proc0;
     94 	struct lwp *l;
     95 	char *name;
     96 	vaddr_t uaddr;
     97 	bool inmem;
     98 	cpuid_t cpuid;
     99 	int error;
    100 
    101 	KASSERT(ci->ci_data.cpu_idlelwp == NULL);
    102 	inmem = uvm_uarea_alloc(&uaddr);
    103 	if (uaddr == 0) {
    104 		return ENOMEM;
    105 	}
    106 	error = newlwp(&lwp0, p, uaddr, inmem, 0, NULL, 0, idle_loop, NULL, &l);
    107 	if (error != 0) {
    108 		panic("create_idle_lwp: newlwp failed");
    109 	}
    110 	uvm_lwp_hold(l);
    111 	l->l_flag |= (LW_IDLE | LW_BOUND);
    112 	l->l_cpu = ci;
    113 	l->l_mutex = &ci->ci_schedstate.spc_lwplock;
    114 	ci->ci_data.cpu_idlelwp = l;
    115 	name = kmem_alloc(MAXCOMLEN, KM_NOSLEEP);
    116 	if (name != NULL) {
    117 #ifdef MULTIPROCESSOR		/* XXX should be mandatory */
    118 		cpuid = ci->ci_cpuid;
    119 #else
    120 		cpuid = 0;
    121 #endif
    122 		snprintf(name, MAXCOMLEN, "idle/%d", (int)cpuid);
    123 		lwp_lock(l);
    124 		l->l_name = name;
    125 		lwp_unlock(l);
    126 	}
    127 	return error;
    128 }
    129