An advanced First Out (FIFO) algorithm for the OS page replacement algorithm

an advanced first-out (FIFO) algorithm for the OS page replacement algorithm

In the operating system page replacement algorithm, the simplest page replacement algorithm is FIFO algorithm. The FIFO page replacement algorithm records the amount of time that the page is transferred into memory for each page. When a page must be replaced, the oldest page is selected. Note that you do not need to record the exact time that a page was transferred. You can create a FIFO queue to manage all pages in memory. The first page in the queue will be replaced. When you need to dial the page, add it to the tail of the queue. The following will simulate the FIFO algorithm in the Java language, where the number of frames is 5, and the page number in the reference string does not contain 0.

Import java.util.LinkedList;
Import java.util.List;

public class FIFO {
public static void Main (string[] args) {
int framesize = 5; Number of Frames
Int[] s = {1, 2, 3, 4, 2, 1, 5, 6, 2, 1, 2, 3, 7, 6, 3, 2, 1, 2, 3, 6}; Reference string
Int[] is = new Int[s.length];
for (int i = 0; i < s.length; i++)
Is[i] = 0;
int aa[][] = new Int[s.length][framesize];
list<integer> q = new linkedlist<integer> ();
int count = 0;
for (int i = 0; i < framesize; i++)
Q.add (0);
for (int i = 0; i < s.length; i++) {
if (!q.contains (new Integer (s[i))) {
Q.remove (0);
Q.add (New Integer (s[i));
count++;
Is[i] = 1;
}
int j = 0;
for (Integer v:q)
Aa[i][j++] = v;
}
for (int i = 0; i < framesize; i++) {
for (int j = 0; J < S.length; J + +) {
System.out.print (Aa[j][i] + "");
}
System.out.println ();
}
System.out.println ();
for (int i = 0; i < s.length; i++) {
System.out.print (Is[i] + "");
}
System.out.println ();
System.out.println ("total:" + count);
}
}

The results of the implementation are as follows:

0 0 0 0 0 0 1 2 2 3 4 5 6 6 6 6 6 6 6-6
0 0 0 1 1 1 2 3 3 4 5 6 1 1 1 1 1 1 1-1
0 0 1 2 2 2 3 4 4 5 6 1 2 2 2 2 2 2 2-2
0 1 2 3 3 3 4 5 5 6 1 2 3 3 3 3 3 3 3-3
1 2 3 4 4 4 5 6 6 1 2 3 7 7 7 7 7 7 7-7
============================
1 1 1 1 0 0 1 1 0 1 1 1 1 0 0 0 0 0 0-0
Total:10

wherein, each column above the equal sign represents a queue, 0 represents an idle frame, and 1 below the equal sign represents a page replacement, and 0 indicates that no page replacement occurred.