title: How do we treat the header while 8-alignment malloc implementation
body: <p>I am trying to build a mymalloc in c programming with 8-byte alignment.
  But I find a problem, if there is a 4-byte header, and 8-byte payload(malloced data),</p>
  <p>Do we have to malloc 16-byte to match the alignment or do we only care about the alignment of payload?</p>