found in page swapping algorithm
s. When using a first-in-first-out
method of page swapping, if you increase the number of frame
s, it is possible that it will increase the number of page fault
s. This is contrary to the intent of adding more frames, thus the anomaly
. This is one reason why a FIFO approach is not recommended.
As an example, take the following list of page references: 123412512345212345.
Here are the frame contents
with three frames*
Now here are the contents with four frames:
So there are fourteen page faults with three frames, but fifteen with four frames. This does not happen with the least-recently-used
*Emphasized frames represent page faults.
**Incidentally, the lru algorithm for this set of page references would result in 15 page faults with three frames and 12 page faults with four frames.