lib/libcaps/uthread.c

   1 /*
   2  * Copyright (c) 2003 Galen Sampson <galen_sampson@yahoo.com>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $DragonFly: src/lib/libcaps/uthread.c,v 1.5 2004/07/29 10:55:02 dillon Exp $
  27  */
  28
  29 /*
  30  * Each cpu in a system has its own self-contained light weight kernel
  31  * thread scheduler, which means that generally speaking we only need
  32  * to use a critical section to avoid problems.  Foreign thread
  33  * scheduling is queued via (async) IPIs.
  34  */
  35
  36 #include "defs.h"
  37
  38 void cpu_lwkt_switch(thread_t);
  39
  40 /*
  41  * system message port for the system call interface
  42  */
  43 lwkt_port_t             sysport;
  44
  45 static void
  46 lwkt_idleloop(void *dummy)
  47 {
  48     globaldata_t gd = mycpu;
  49
  50     DBPRINTF(("idlestart cpu %d pri %d (should be < 32) mpcount %d (should be 0)\n",
  51         gd->gd_cpuid, curthread->td_pri, curthread->td_mpcount));
  52
  53     gd->gd_pid = getpid();
  54
  55     for (;;) {
  56         /*
  57          * If only our 'main' thread is left, schedule it.
  58          */
  59         if (gd->gd_num_threads == gd->gd_sys_threads) {
  60             int i;
  61             globaldata_t tgd;
  62
  63             for (i = 0; i < ncpus; ++i) {
  64                 tgd = globaldata_find(i);
  65                 if (tgd->gd_num_threads != tgd->gd_sys_threads)
  66                     break;
  67             }
  68             if (i == ncpus && (main_td.td_flags & TDF_RUNQ) == 0)
  69                 lwkt_schedule(&main_td);
  70         }
  71
  72         /*
  73          * Wait for an interrupt, aka wait for a signal or an upcall to
  74          * occur, then switch away.
  75          */
  76         crit_enter();
  77         if (gd->gd_runqmask || (curthread->td_flags & TDF_IDLE_NOHLT)) {
  78             curthread->td_flags &= ~TDF_IDLE_NOHLT;
  79         } else {
  80             printf("cpu %d halting\n", gd->gd_cpuid);
  81             cpu_halt();
  82             printf("cpu %d resuming\n", gd->gd_cpuid);
  83         }
  84         crit_exit();
  85         lwkt_switch();
  86     }
  87 }
  88
  89 /*
  90  * Userland override of lwkt_init_thread. The only difference is
  91  * the manipulation of gd->gd_num_threads.
  92  */
  93 static void
  94 lwkt_init_thread_remote(void *arg)
  95 {
  96     thread_t td = arg;
  97     globaldata_t gd = td->td_gd;
  98
  99     printf("init_thread_remote td %p on cpu %d\n", td, gd->gd_cpuid);
 100
 101     TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq);
 102     ++gd->gd_num_threads;
 103     if (td->td_flags & TDF_SYSTHREAD)
 104         ++gd->gd_sys_threads;
 105 }
 106
 107 void
 108 lwkt_init_thread(thread_t td, void *stack, int stksize, int flags,
 109                 struct globaldata *gd)
 110 {
 111     bzero(td, sizeof(struct thread));
 112     td->td_kstack = stack;
 113     td->td_kstack_size = stksize;
 114     td->td_flags |= flags;
 115     td->td_gd = gd;
 116     td->td_pri = TDPRI_KERN_DAEMON + TDPRI_CRIT;
 117     lwkt_initport(&td->td_msgport, td);
 118     cpu_init_thread(td);
 119     if (td == &gd->gd_idlethread) {
 120         TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq);
 121         /* idle thread is not counted in gd_num_threads */
 122     } else if (gd == mycpu) {
 123         crit_enter();
 124         TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq);
 125         ++gd->gd_num_threads;
 126         if (td->td_flags & TDF_SYSTHREAD)
 127             ++gd->gd_sys_threads;
 128         crit_exit();
 129     } else {
 130         lwkt_send_ipiq(gd, lwkt_init_thread_remote, td);
 131     }
 132 }
 133
 134 /*
 135  * Userland override of lwkt_exit. The only difference is
 136  * the manipulation of gd->gd_num_threads;
 137  */
 138 void
 139 lwkt_exit(void)
 140 {
 141     thread_t td = curthread;
 142     globaldata_t gd = mycpu;
 143
 144     if (td->td_flags & TDF_VERBOSE)
 145         printf("kthread %p %s has exited\n", td, td->td_comm);
 146     crit_enter();
 147     lwkt_deschedule_self(td);
 148     ++gd->gd_tdfreecount;
 149     if (td->td_flags & TDF_SYSTHREAD)
 150         --gd->gd_sys_threads;
 151     --gd->gd_num_threads;
 152     TAILQ_INSERT_TAIL(&gd->gd_tdfreeq, td, td_threadq);
 153     cpu_thread_exit();
 154 }
 155
 156 /*
 157  * Userland override of lwkt_gdinit.  Called from mi_gdinit().  Note that
 158  * critical sections do not work until lwkt_init_thread() is called.  The
 159  * idle thread will be left in a critical section.
 160  */
 161 void
 162 lwkt_gdinit(struct globaldata *gd)
 163 {
 164     int i;
 165
 166     for (i = 0; i < sizeof(gd->gd_tdrunq)/sizeof(gd->gd_tdrunq[0]); ++i)
 167         TAILQ_INIT(&gd->gd_tdrunq[i]);
 168     gd->gd_runqmask = 0;
 169     gd->gd_curthread = &gd->gd_idlethread;
 170     TAILQ_INIT(&gd->gd_tdallq);
 171
 172     /* Set up this cpu's idle thread */
 173     lwkt_init_thread(&gd->gd_idlethread,
 174                 libcaps_alloc_stack(LWKT_THREAD_STACK), LWKT_THREAD_STACK,
 175                 0, gd);
 176     cpu_set_thread_handler(&gd->gd_idlethread, lwkt_exit, lwkt_idleloop, NULL);
 177 }
 178
 179 /*
 180  * Start threading.
 181  */
 182 void
 183 lwkt_start_threading(thread_t td)
 184 {
 185     lwkt_switch();
 186 }
 187