  We present a comparison of a number of iterative solvers of linear systems of
equations for obtaining the fermion propagator in lattice QCD. In particular,
we consider chirally invariant overlap and chirally improved Wilson (maximally)
twisted mass fermions. The comparison of both formulations of lattice QCD is
performed at four fixed values of the pion mass between 230MeV and 720MeV. For
overlap fermions we address adaptive precision and low mode preconditioning
while for twisted mass fermions we discuss even/odd preconditioning. Taking the
best available algorithms in each case we find that calculations with the
overlap operator are by a factor of 30-120 more expensive than with the twisted
mass operator.
