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