98 lines
2.7 KiB
C
98 lines
2.7 KiB
C
/*
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* @author xamidev <xamidev@riseup.net>
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* @brief Round-robin scheduler
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* @license GPL-3.0-only
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*/
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#include <kernel.h>
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#include <sched/process.h>
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#include <mem/paging.h>
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#include <stdint.h>
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#include <io/serial/serial.h>
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#include <arch/gdt.h>
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extern struct process* processes_list;
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extern struct process* current_process;
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extern struct process* idle_proc;
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extern struct tss tss;
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/*
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* scheduler_init - Choose the first process
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*/
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void scheduler_init()
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{
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current_process = processes_list;
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DEBUG("scheduler starting with: pid=%u, name='%s', context=%p", current_process->pid, current_process->name, current_process->context);
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}
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/*
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* scheduler_schedule - Main scheduling routine
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* @context: CPU context of previous process
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*
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* Chooses the next process that we should run.
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* The routine is executed every SCHEDULER_QUANTUM ticks.
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*
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* Return:
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* <context> - CPU context for next process
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*/
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struct cpu_status* scheduler_schedule(struct cpu_status* context)
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{
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if (context == NULL) {
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panic(NULL, "Scheduler called with NULL context");
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}
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if (current_process == NULL) {
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panic(NULL, "current_process is NULL");
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}
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if (current_process->context == NULL) {
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panic(NULL, "current_process->context is NULL");
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}
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current_process->context = context;
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if (current_process->status == DEAD) {
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struct process* dead_process = current_process;
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struct process* next_process = (dead_process->next != NULL) ? dead_process->next : processes_list;
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process_delete(&processes_list, dead_process);
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if (processes_list == NULL || next_process == dead_process) {
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current_process = idle_proc;
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return idle_proc->context;
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}
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current_process = next_process;
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} else if (current_process->next != NULL) {
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current_process = current_process->next;
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} else {
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current_process = processes_list;
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}
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for (;;) {
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if (current_process->status == DEAD) {
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struct process* dead_process = current_process;
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struct process* next_process = (current_process->next != NULL) ? current_process->next : processes_list;
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process_delete(&processes_list, dead_process);
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if (processes_list == NULL || next_process == dead_process) {
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current_process = idle_proc;
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return idle_proc->context;
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}
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current_process = next_process;
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continue;
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}
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current_process->status = RUNNING;
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break;
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}
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// Here, we chose next running process so we load its kernel stack & page tables
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tss.rsp0 = (uint64_t)current_process->kernel_stack;
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load_cr3(VIRT_TO_PHYS((uint64_t)current_process->root_page_table));
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return current_process->context;
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} |