Demo: Which View Each Step Edits

Reserve 4 MB, write byte 0 of every page, write byte 4095 of every page, unmap.

Run

Two terminals. First:

make
./reserve_allocate

Second, at every prompt:

ps -o pid,comm,vsz,rss,min_flt,maj_flt -p $(pidof reserve_allocate)

Ask

• After mmap(): which column moved, and which structure did that edit?
• After the first writes: which columns moved, and by how many pages?
• After the second writes: why did nothing move?