Modeling Page Replacement Algorithms

Presentasi berjudul: "Modeling Page Replacement Algorithms"— Transcript presentasi:

1 Modeling Page Replacement Algorithms

2 Belady’s Anomaly Reference Pages:

3 Belady’s Anomaly

4 Stacks Algorithms Definisi dari Stack Algoritm ? Contoh:
Reference String terdiri dari 4 Pages: Reference String terdiri dari 5 Pages:

5 Memprediksi Page Fault Rates

6 Memprediksi Page Fault Rates

7 Distance String

8 Isu Perancangan untuk Sistem Paging
Local Vs Global Allocation Policies

9 Page Fault Rates

10 Page Size Want to set page size to reduce internal fragmentation
Smaller page size leads to more pages leads to larger page table What is optimal page size? p = page size = ? s = average process size, e = size of each page table entry s/p = average number of pages per process (s/p)*e = space taken up by average process in page table p/2 = average wasted memory in last page of process due to internal fragmentation overhead = (s/p)*e + p/2 Find optimal page size by taking derivative and setting to 0 p = 2se

11 Process with a subset of pages in main memory

12 Swap out area  disk image of the logical address spaces of a process

13 Isu Implementasi Tahapan Page Fault Handling Locking Pages in Memory
Backing Store

14 Handling a Page Fault

15 Segmentation

16 Segmentation

17 Segmentation

18 Segmentation

19 Latihan Hitung jumlah page fault jika diketahui Reference String sbb:, dan memori terdiri dari 4 Pages: Dengan algoritma: FIFO LRU Optimal