  We present details of our implementation of the Wuppertal adaptive algebraic
multigrid code DD-$\alpha$AMG on SIMD architectures, with particular emphasis
on the Intel Xeon Phi processor (KNC) used in QPACE 2. As a smoother, the
algorithm uses a domain-decomposition-based solver code previously developed
for the KNC in Regensburg. We optimized the remaining parts of the multigrid
code and conclude that it is a very good target for SIMD architectures. Some of
the remaining bottlenecks can be eliminated by vectorizing over multiple test
vectors in the setup, which is discussed in the contribution of Daniel
Richtmann.
