374 lines
10 KiB
C
374 lines
10 KiB
C
/* This file contains the scheduling policy for SCHED
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*
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* The entry points are:
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* do_noquantum: Called on behalf of process' that run out of quantum
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* do_start_scheduling Request to start scheduling a proc
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* do_stop_scheduling Request to stop scheduling a proc
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* do_nice Request to change the nice level on a proc
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* init_scheduling Called from main.c to set up/prepare scheduling
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*/
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#include "sched.h"
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#include "schedproc.h"
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#include <assert.h>
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#include <minix/com.h>
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#include <machine/archtypes.h>
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#include "kernel/proc.h" /* for queue constants */
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static minix_timer_t sched_timer;
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static unsigned balance_timeout;
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#define BALANCE_TIMEOUT 5 /* how often to balance queues in seconds */
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static int schedule_process(struct schedproc * rmp, unsigned flags);
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static void balance_queues(minix_timer_t *tp);
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#define SCHEDULE_CHANGE_PRIO 0x1
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#define SCHEDULE_CHANGE_QUANTUM 0x2
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#define SCHEDULE_CHANGE_CPU 0x4
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#define SCHEDULE_CHANGE_ALL ( \
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SCHEDULE_CHANGE_PRIO | \
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SCHEDULE_CHANGE_QUANTUM | \
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SCHEDULE_CHANGE_CPU \
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)
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#define schedule_process_local(p) \
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schedule_process(p, SCHEDULE_CHANGE_PRIO | SCHEDULE_CHANGE_QUANTUM)
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#define schedule_process_migrate(p) \
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schedule_process(p, SCHEDULE_CHANGE_CPU)
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#define CPU_DEAD -1
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#define cpu_is_available(c) (cpu_proc[c] >= 0)
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#define DEFAULT_USER_TIME_SLICE 200
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/* processes created by RS are sysytem processes */
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#define is_system_proc(p) ((p)->parent == RS_PROC_NR)
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static unsigned cpu_proc[CONFIG_MAX_CPUS];
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static void pick_cpu(struct schedproc * proc)
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{
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#ifdef CONFIG_SMP
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unsigned cpu, c;
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unsigned cpu_load = (unsigned) -1;
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if (machine.processors_count == 1) {
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proc->cpu = machine.bsp_id;
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return;
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}
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/* schedule sysytem processes only on the boot cpu */
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if (is_system_proc(proc)) {
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proc->cpu = machine.bsp_id;
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return;
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}
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/* if no other cpu available, try BSP */
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cpu = machine.bsp_id;
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for (c = 0; c < machine.processors_count; c++) {
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/* skip dead cpus */
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if (!cpu_is_available(c))
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continue;
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if (c != machine.bsp_id && cpu_load > cpu_proc[c]) {
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cpu_load = cpu_proc[c];
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cpu = c;
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}
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}
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proc->cpu = cpu;
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cpu_proc[cpu]++;
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#else
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proc->cpu = 0;
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#endif
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}
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/*===========================================================================*
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* do_noquantum *
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*===========================================================================*/
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int do_noquantum(message *m_ptr)
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{
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register struct schedproc *rmp;
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int rv, proc_nr_n;
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if (sched_isokendpt(m_ptr->m_source, &proc_nr_n) != OK) {
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printf("SCHED: WARNING: got an invalid endpoint in OOQ msg %u.\n",
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m_ptr->m_source);
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return EBADEPT;
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}
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rmp = &schedproc[proc_nr_n];
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if (rmp->priority < MIN_USER_Q) {
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rmp->priority += 1; /* lower priority */
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}
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if ((rv = schedule_process_local(rmp)) != OK) {
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return rv;
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}
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return OK;
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}
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/*===========================================================================*
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* do_stop_scheduling *
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*===========================================================================*/
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int do_stop_scheduling(message *m_ptr)
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{
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register struct schedproc *rmp;
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int proc_nr_n;
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/* check who can send you requests */
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if (!accept_message(m_ptr))
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return EPERM;
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if (sched_isokendpt(m_ptr->m_lsys_sched_scheduling_stop.endpoint,
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&proc_nr_n) != OK) {
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printf("SCHED: WARNING: got an invalid endpoint in OOQ msg "
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"%d\n", m_ptr->m_lsys_sched_scheduling_stop.endpoint);
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return EBADEPT;
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}
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rmp = &schedproc[proc_nr_n];
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#ifdef CONFIG_SMP
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cpu_proc[rmp->cpu]--;
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#endif
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rmp->flags = 0; /*&= ~IN_USE;*/
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return OK;
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}
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/*===========================================================================*
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* do_start_scheduling *
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*===========================================================================*/
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int do_start_scheduling(message *m_ptr)
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{
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register struct schedproc *rmp;
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int rv, proc_nr_n, parent_nr_n;
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/* we can handle two kinds of messages here */
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assert(m_ptr->m_type == SCHEDULING_START ||
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m_ptr->m_type == SCHEDULING_INHERIT);
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/* check who can send you requests */
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if (!accept_message(m_ptr))
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return EPERM;
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/* Resolve endpoint to proc slot. */
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if ((rv = sched_isemtyendpt(m_ptr->m_lsys_sched_scheduling_start.endpoint,
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&proc_nr_n)) != OK) {
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return rv;
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}
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rmp = &schedproc[proc_nr_n];
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/* Populate process slot */
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rmp->endpoint = m_ptr->m_lsys_sched_scheduling_start.endpoint;
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rmp->parent = m_ptr->m_lsys_sched_scheduling_start.parent;
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rmp->max_priority = m_ptr->m_lsys_sched_scheduling_start.maxprio;
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if (rmp->max_priority >= NR_SCHED_QUEUES) {
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return EINVAL;
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}
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/* Inherit current priority and time slice from parent. Since there
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* is currently only one scheduler scheduling the whole system, this
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* value is local and we assert that the parent endpoint is valid */
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if (rmp->endpoint == rmp->parent) {
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/* We have a special case here for init, which is the first
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process scheduled, and the parent of itself. */
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rmp->priority = USER_Q;
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rmp->time_slice = DEFAULT_USER_TIME_SLICE;
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/*
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* Since kernel never changes the cpu of a process, all are
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* started on the BSP and the userspace scheduling hasn't
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* changed that yet either, we can be sure that BSP is the
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* processor where the processes run now.
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*/
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#ifdef CONFIG_SMP
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rmp->cpu = machine.bsp_id;
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/* FIXME set the cpu mask */
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#endif
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}
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switch (m_ptr->m_type) {
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case SCHEDULING_START:
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/* We have a special case here for system processes, for which
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* quanum and priority are set explicitly rather than inherited
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* from the parent */
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rmp->priority = rmp->max_priority;
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rmp->time_slice = m_ptr->m_lsys_sched_scheduling_start.quantum;
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break;
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case SCHEDULING_INHERIT:
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/* Inherit current priority and time slice from parent. Since there
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* is currently only one scheduler scheduling the whole system, this
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* value is local and we assert that the parent endpoint is valid */
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if ((rv = sched_isokendpt(m_ptr->m_lsys_sched_scheduling_start.parent,
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&parent_nr_n)) != OK)
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return rv;
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rmp->priority = schedproc[parent_nr_n].priority;
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rmp->time_slice = schedproc[parent_nr_n].time_slice;
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break;
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default:
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/* not reachable */
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assert(0);
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}
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/* Take over scheduling the process. The kernel reply message populates
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* the processes current priority and its time slice */
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if ((rv = sys_schedctl(0, rmp->endpoint, 0, 0, 0)) != OK) {
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printf("Sched: Error taking over scheduling for %d, kernel said %d\n",
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rmp->endpoint, rv);
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return rv;
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}
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rmp->flags = IN_USE;
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/* Schedule the process, giving it some quantum */
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pick_cpu(rmp);
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while ((rv = schedule_process(rmp, SCHEDULE_CHANGE_ALL)) == EBADCPU) {
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/* don't try this CPU ever again */
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cpu_proc[rmp->cpu] = CPU_DEAD;
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pick_cpu(rmp);
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}
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if (rv != OK) {
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printf("Sched: Error while scheduling process, kernel replied %d\n",
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rv);
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return rv;
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}
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/* Mark ourselves as the new scheduler.
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* By default, processes are scheduled by the parents scheduler. In case
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* this scheduler would want to delegate scheduling to another
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* scheduler, it could do so and then write the endpoint of that
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* scheduler into the "scheduler" field.
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*/
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m_ptr->m_sched_lsys_scheduling_start.scheduler = SCHED_PROC_NR;
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return OK;
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}
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/*===========================================================================*
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* do_nice *
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*===========================================================================*/
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int do_nice(message *m_ptr)
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{
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struct schedproc *rmp;
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int rv;
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int proc_nr_n;
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unsigned new_q, old_q, old_max_q;
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/* check who can send you requests */
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if (!accept_message(m_ptr))
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return EPERM;
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if (sched_isokendpt(m_ptr->m_pm_sched_scheduling_set_nice.endpoint, &proc_nr_n) != OK) {
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printf("SCHED: WARNING: got an invalid endpoint in OoQ msg "
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"%d\n", m_ptr->m_pm_sched_scheduling_set_nice.endpoint);
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return EBADEPT;
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}
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rmp = &schedproc[proc_nr_n];
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new_q = m_ptr->m_pm_sched_scheduling_set_nice.maxprio;
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if (new_q >= NR_SCHED_QUEUES) {
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return EINVAL;
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}
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/* Store old values, in case we need to roll back the changes */
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old_q = rmp->priority;
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old_max_q = rmp->max_priority;
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/* Update the proc entry and reschedule the process */
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rmp->max_priority = rmp->priority = new_q;
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if ((rv = schedule_process_local(rmp)) != OK) {
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/* Something went wrong when rescheduling the process, roll
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* back the changes to proc struct */
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rmp->priority = old_q;
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rmp->max_priority = old_max_q;
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}
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return rv;
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}
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/*===========================================================================*
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* schedule_process *
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*===========================================================================*/
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static int schedule_process(struct schedproc * rmp, unsigned flags)
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{
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int err;
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int new_prio, new_quantum, new_cpu;
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pick_cpu(rmp);
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if (flags & SCHEDULE_CHANGE_PRIO)
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new_prio = rmp->priority;
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else
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new_prio = -1;
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if (flags & SCHEDULE_CHANGE_QUANTUM)
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new_quantum = rmp->time_slice;
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else
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new_quantum = -1;
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if (flags & SCHEDULE_CHANGE_CPU)
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new_cpu = rmp->cpu;
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else
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new_cpu = -1;
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//processes are swapped here
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if (rmp->priority >= 7 && rmp->max_priority == 7)
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{
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printf("MINIX: PID %d swapped in\n", _ENDPOINT_P(rmp->endpoint));
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}
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if ((err = sys_schedule(rmp->endpoint, new_prio,
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new_quantum, new_cpu)) != OK) {
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printf("PM: An error occurred when trying to schedule %d: %d\n",
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rmp->endpoint, err);
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}
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return err;
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}
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/*===========================================================================*
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* start_scheduling *
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*===========================================================================*/
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void init_scheduling(void)
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{
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balance_timeout = BALANCE_TIMEOUT * sys_hz();
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init_timer(&sched_timer);
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set_timer(&sched_timer, balance_timeout, balance_queues, 0);
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}
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/*===========================================================================*
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* balance_queues *
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*===========================================================================*/
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/* This function in called every 100 ticks to rebalance the queues. The current
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* scheduler bumps processes down one priority when ever they run out of
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* quantum. This function will find all proccesses that have been bumped down,
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* and pulls them back up. This default policy will soon be changed.
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*/
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static void balance_queues(minix_timer_t *tp)
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{
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struct schedproc *rmp;
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int proc_nr;
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for (proc_nr=0, rmp=schedproc; proc_nr < NR_PROCS; proc_nr++, rmp++) {
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if (rmp->flags & IN_USE) {
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if (rmp->priority > rmp->max_priority) {
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rmp->priority -= 1; /* increase priority */
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schedule_process_local(rmp);
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}
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}
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}
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set_timer(&sched_timer, balance_timeout, balance_queues, 0);
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}
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