nu                 47 user/umalloc.c morecore(uint nu)
nu                 52 user/umalloc.c   if(nu < 4096)
nu                 53 user/umalloc.c     nu = 4096;
nu                 54 user/umalloc.c   p = sbrk(nu * sizeof(Header));
nu                 58 user/umalloc.c   hp->s.size = nu;