MMAP_CHUNK
e1 = m1 + MMAP_CHUNK;
e2 = m2 + MMAP_CHUNK;
off1 += MMAP_CHUNK;
munmap(m2, MMAP_CHUNK);
e1 = m1 + MMAP_CHUNK;
off2 += MMAP_CHUNK;
munmap(m1, MMAP_CHUNK);
e2 = m2 + MMAP_CHUNK;
munmap(m1, MMAP_CHUNK);
munmap(m2, MMAP_CHUNK);
munmap(mem, MMAP_CHUNK);
mem = mmap(NULL, MMAP_CHUNK, PROT_READ, MAP_SHARED, fd, offset);
madvise(mem, MMAP_CHUNK, MADV_SEQUENTIAL);
munmap(m1, MMAP_CHUNK);