Demo: Minor and Major, on the Same File

Run

make
./major_fault
fincore data.bin 2>/dev/null

Not on /tmp: the directory has to be on a real disk.

Ask

• 16,384 major faults, then 0. What changed between the two passes?
• 0.3 s against 0.002 s, for the same instructions. Where did the time go?
• The second pass took 1,024 faults for 16,384 pages. What did the kernel do with the other 15 in each 16?