25'ten fazla konu seçemezsiniz
Konular bir harf veya rakamla başlamalı, kısa çizgiler ('-') içerebilir ve en fazla 35 karakter uzunluğunda olabilir.
136 satır
4.9 KiB
136 satır
4.9 KiB
#include <defs.h>
|
|
#include <x86.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <swap.h>
|
|
#include <swap_fifo.h>
|
|
#include <list.h>
|
|
|
|
/* [wikipedia]The simplest Page Replacement Algorithm(PRA) is a FIFO algorithm. The first-in, first-out
|
|
* page replacement algorithm is a low-overhead algorithm that requires little book-keeping on
|
|
* the part of the operating system. The idea is obvious from the name - the operating system
|
|
* keeps track of all the pages in memory in a queue, with the most recent arrival at the back,
|
|
* and the earliest arrival in front. When a page needs to be replaced, the page at the front
|
|
* of the queue (the oldest page) is selected. While FIFO is cheap and intuitive, it performs
|
|
* poorly in practical application. Thus, it is rarely used in its unmodified form. This
|
|
* algorithm experiences Belady's anomaly.
|
|
*
|
|
* Details of FIFO PRA
|
|
* (1) Prepare: In order to implement FIFO PRA, we should manage all swappable pages, so we can
|
|
* link these pages into pra_list_head according the time order. At first you should
|
|
* be familiar to the struct list in list.h. struct list is a simple doubly linked list
|
|
* implementation. You should know howto USE: list_init, list_add(list_add_after),
|
|
* list_add_before, list_del, list_next, list_prev. Another tricky method is to transform
|
|
* a general list struct to a special struct (such as struct page). You can find some MACRO:
|
|
* le2page (in memlayout.h), (in future labs: le2vma (in vmm.h), le2proc (in proc.h),etc.
|
|
*/
|
|
|
|
list_entry_t pra_list_head;
|
|
/*
|
|
* (2) _fifo_init_mm: init pra_list_head and let mm->sm_priv point to the addr of pra_list_head.
|
|
* Now, From the memory control struct mm_struct, we can access FIFO PRA
|
|
*/
|
|
static int
|
|
_fifo_init_mm(struct mm_struct *mm)
|
|
{
|
|
list_init(&pra_list_head);
|
|
mm->sm_priv = &pra_list_head;
|
|
//cprintf(" mm->sm_priv %x in fifo_init_mm\n",mm->sm_priv);
|
|
return 0;
|
|
}
|
|
/*
|
|
* (3)_fifo_map_swappable: According FIFO PRA, we should link the most recent arrival page at the back of pra_list_head qeueue
|
|
*/
|
|
static int
|
|
_fifo_map_swappable(struct mm_struct *mm, uintptr_t addr, struct Page *page, int swap_in)
|
|
{
|
|
list_entry_t *head=(list_entry_t*) mm->sm_priv;
|
|
list_entry_t *entry=&(page->pra_page_link);
|
|
|
|
assert(entry != NULL && head != NULL);
|
|
//record the page access situlation
|
|
/*LAB3 EXERCISE 2: YOUR CODE*/
|
|
//(1)link the most recent arrival page at the back of the pra_list_head qeueue.
|
|
return 0;
|
|
}
|
|
/*
|
|
* (4)_fifo_swap_out_victim: According FIFO PRA, we should unlink the earliest arrival page in front of pra_list_head qeueue,
|
|
* then set the addr of addr of this page to ptr_page.
|
|
*/
|
|
static int
|
|
_fifo_swap_out_victim(struct mm_struct *mm, struct Page ** ptr_page, int in_tick)
|
|
{
|
|
list_entry_t *head=(list_entry_t*) mm->sm_priv;
|
|
assert(head != NULL);
|
|
assert(in_tick==0);
|
|
/* Select the victim */
|
|
/*LAB3 EXERCISE 2: YOUR CODE*/
|
|
//(1) unlink the earliest arrival page in front of pra_list_head qeueue
|
|
//(2) set the addr of addr of this page to ptr_page
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
_fifo_check_swap(void) {
|
|
cprintf("write Virt Page c in fifo_check_swap\n");
|
|
*(unsigned char *)0x3000 = 0x0c;
|
|
assert(pgfault_num==4);
|
|
cprintf("write Virt Page a in fifo_check_swap\n");
|
|
*(unsigned char *)0x1000 = 0x0a;
|
|
assert(pgfault_num==4);
|
|
cprintf("write Virt Page d in fifo_check_swap\n");
|
|
*(unsigned char *)0x4000 = 0x0d;
|
|
assert(pgfault_num==4);
|
|
cprintf("write Virt Page b in fifo_check_swap\n");
|
|
*(unsigned char *)0x2000 = 0x0b;
|
|
assert(pgfault_num==4);
|
|
cprintf("write Virt Page e in fifo_check_swap\n");
|
|
*(unsigned char *)0x5000 = 0x0e;
|
|
assert(pgfault_num==5);
|
|
cprintf("write Virt Page b in fifo_check_swap\n");
|
|
*(unsigned char *)0x2000 = 0x0b;
|
|
assert(pgfault_num==5);
|
|
cprintf("write Virt Page a in fifo_check_swap\n");
|
|
*(unsigned char *)0x1000 = 0x0a;
|
|
assert(pgfault_num==6);
|
|
cprintf("write Virt Page b in fifo_check_swap\n");
|
|
*(unsigned char *)0x2000 = 0x0b;
|
|
assert(pgfault_num==7);
|
|
cprintf("write Virt Page c in fifo_check_swap\n");
|
|
*(unsigned char *)0x3000 = 0x0c;
|
|
assert(pgfault_num==8);
|
|
cprintf("write Virt Page d in fifo_check_swap\n");
|
|
*(unsigned char *)0x4000 = 0x0d;
|
|
assert(pgfault_num==9);
|
|
return 0;
|
|
}
|
|
|
|
|
|
static int
|
|
_fifo_init(void)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
_fifo_set_unswappable(struct mm_struct *mm, uintptr_t addr)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
_fifo_tick_event(struct mm_struct *mm)
|
|
{ return 0; }
|
|
|
|
|
|
struct swap_manager swap_manager_fifo =
|
|
{
|
|
.name = "fifo swap manager",
|
|
.init = &_fifo_init,
|
|
.init_mm = &_fifo_init_mm,
|
|
.tick_event = &_fifo_tick_event,
|
|
.map_swappable = &_fifo_map_swappable,
|
|
.set_unswappable = &_fifo_set_unswappable,
|
|
.swap_out_victim = &_fifo_swap_out_victim,
|
|
.check_swap = &_fifo_check_swap,
|
|
};
|