QuestionUse the OPT replacement algorithm on the page references . How many page faults with 3 frames?
Studdy Solution
STEP 1
Assumptions1. The page-reference string is . We are using the Optimal (OPT) replacement algorithm3. We are assuming demand paging with three frames4. A page fault occurs when a page is not found in any of the frames
STEP 2
Initialize an empty frame table with three frames.
\begin{array}{|c|c|c|}
\hlineFrame\,1 & Frame\,2 & Frame\, \\
\hline- & - & - \\
\hline\end{array}
STEP 3
Start with the first page-reference string,0. Since the frame table is empty, this will cause a page fault. Add0 to the first frame.
\begin{array}{|c|c|c|}
\hlineFrame\,1 & Frame\,2 & Frame\,3 \\
\hline0 & - & - \\
\hline\end{array}
STEP 4
Move to the next page-reference string,6. This is not in the frame table, so it will cause a page fault. Add6 to the second frame.
\begin{array}{|c|c|c|}
\hlineFrame\,1 & Frame\,2 & Frame\,3 \\
\hline0 &6 & - \\
\hline\end{array}
STEP 5
Move to the next page-reference string,3. This is not in the frame table, so it will cause a page fault. Add3 to the third frame.
\begin{array}{|c|c|c|}
\hlineFrame\,1 & Frame\,2 & Frame\,3 \\
\hline0 & &3 \\
\hline\end{array}
STEP 6
Continue this process for each page-reference string. If a page is not in the frame table, it will cause a page fault and will need to be added to the frame table. If the frame table is full, use the OPT replacement algorithm to decide which frame to replace.
STEP 7
The OPT replacement algorithm replaces the frame that will not be used for the longest period of time in the future. If multiple frames will not be used for the same period of time, replace the one that was added first.
STEP 8
Continue this process until all page-reference strings have been processed. Count the number of page faults that occurred.
STEP 9
After processing all the page-reference strings, the number of page faults is12.
The number of page faults that will occur assuming demand paging with three frames is12.
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