A system uses 3-level paging. Memory access time is 100 ns and TLB access time is 20 ns. What is the access time in nanoseconds for a TLB MISS?
$TLB miss access time = TLB_time + (levels + 1) * Memory_time = 20 + (3 + 1) * 100 = 20 + 400 = 420 ns.$
A process needs 5 frames to avoid thrashing. If physical memory has 32 frames and 8 identical processes are running, what is the maximum number of processes that can run simultaneously without thrashing?
Available frames = 32. Each process needs 5 frames. Max non-thrashing processes = floor(32 / 5) = 6 processes.
Consider 4 dynamic memory holes of sizes 100 KB, 500 KB, 200 KB, 300 KB (in order). Which hole size (in KB) will Best-Fit assign to a process requesting 180 KB?
Holes >= 180 KB are 500 KB, 200 KB, 300 KB. Best-Fit selects the smallest among these, which is 200 KB.
In inverted page table mapping, physical RAM is 1 GB and frame size is 4 KB. How many entries are in the inverted page table?
$Physical RAM = 1 GB = 2^30 bytes. Frame size = 4 KB = 2^12 bytes. Number of entries = 2^30 / 2^12 = 2^18 = 262,144 entries.$
If page fault rate $p = 0.001, memory access time = 100 ns, page fault service time = 10 ms (10,000,000 ns)$, calculate Effective Memory Access Time in nanoseconds.
EAT = (1 - 0.001) * 100 + 0.001 * 10,000,000 = 0.999 * 100 + 10,000 = 99.9 + 10,000 = 10,099.9 ns.