diff options
| author | Jake Mannens <jake72360@gmail.com> | 2018-07-11 05:38:01 +1000 |
|---|---|---|
| committer | Jake Mannens <jake72360@gmail.com> | 2018-07-11 05:38:01 +1000 |
| commit | 59cac783f5ba12a47308b05b87d5cfa769473a49 (patch) | |
| tree | 35e14bb57fa7fdbaf1573f409c3289e1ddb9c0c1 /kernel | |
| parent | 99d16e98e04c73e108160d7d70244bafdb33b6fc (diff) | |
Modified the tick_handler interrupt routine in timer.s so that it no
longer calls reschedule() directly. It now calls sched_tick() so that
the scheduler can make it's own decisions relating to handling the timer
interrupt.
The reschedule() function now *actually* implements a basic round-robin
scheduling algorithm that iterates through the list of tasks. This is
still a temporary algorithm but at least it now includes *all* runnable
processes instead of switching back and forth between process 1 and 2.
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/asm.s | 5 | ||||
| -rw-r--r-- | kernel/sched.c | 18 | ||||
| -rw-r--r-- | kernel/timer.s | 4 |
3 files changed, 20 insertions, 7 deletions
diff --git a/kernel/asm.s b/kernel/asm.s index 0bf9067..6d35334 100644 --- a/kernel/asm.s +++ b/kernel/asm.s @@ -3,6 +3,7 @@ global switch_to global set_tss extern cstate extern ctask +extern ctaskn extern gdt extern save_state @@ -27,9 +28,11 @@ switch_to: ltr ax ; copy the saved state into the previous TSS call save_state - ; update ctask + ; update ctask and ctaskn mov ebx, [ebp+12] mov [ctask], ebx + mov ebx, [ebp+8] + mov [ctaskn], ebx ; calculate the task segment index and jump to it mov ebx, [ebp+8] add ebx, 5 diff --git a/kernel/sched.c b/kernel/sched.c index dd75d47..8469005 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -48,6 +48,7 @@ struct task_state { } __attribute__((packed)); struct task_struct *ctask; +uint32_t ctaskn; struct task_state *cstate; static struct task_struct tasks[NRTASKS]; @@ -194,6 +195,7 @@ void sched_init(void) { create_proc(&_usrbin_start, (size_t) &_usrbin_size); create_proc(&_usrbin_start, (size_t) &_usrbin_size); + create_proc(&_usrbin_start, (size_t) &_usrbin_size); switch_to(0, &tasks[0]); } @@ -221,12 +223,20 @@ void save_state(void) { } void reschedule(void) { + int i; + uint32_t n; + if(ctask == NULL) return; - if(ctask == &tasks[0]) { - switch_to(1, &tasks[1]); - } else { - switch_to(0, &tasks[0]); + n = ctaskn; + for(i = 0; i < NRTASKS; i++) { + n = (n + 1) % NRTASKS; + if(tasks[n].pid) + switch_to(n, &tasks[n]); } } + +void sched_tick(void) { + reschedule(); +} diff --git a/kernel/timer.s b/kernel/timer.s index c84a847..12ea9d0 100644 --- a/kernel/timer.s +++ b/kernel/timer.s @@ -2,7 +2,7 @@ global ticks global timer_init extern cstate extern register_isr -extern reschedule +extern sched_tick ticks: dd 0 @@ -26,7 +26,7 @@ tick_handler: out 0x20, al ; call the scheduler - call reschedule + call sched_tick ; restore the data segment selectors pop ax |