câu 36

Link will be apear in 30 seconds.

Well done! you have successfully gained access to Decrypted Link.

Question:

A computer has four page frames. The time of loading, time of last access, and the R and M bits for each page are as shown below (the times are in clock ticks):

(a) Which page will NRU replace?
(b) Which page will FIFO replace?
(c) Which page will LRU replace?
(d) Which page will second chance replace?

---

Answer:

(a) NRU: 2(

page 2, because R=0 and M=0)

(b) FIFO: 3(

page 3, because it was loaded first)

(c) LRU: 1(

 page 0, becuase it hasn't been used for longest time.)

(d) Second Chance: 2(

 1st candidate: page frame 3 (because it was loaded from
              disk first).  But! It's R bit is 1. 
              So 2nd chance allows it to stay.
              2nd candidate: page frame 0 (because it was loaded from
              disk next) It's R bit is 0, so page frame 0 is 
              chosen to be evicted.
        )