  We study quantum quenches and subsequent non-equilibrium dynamics of free
Dirac fermions in 1+1 spacetime dimensions using time dependent mass. The final
state is a normalized boundary state which is called generalized
Calabrese-Cardy (gCC) state and the system thermalizes to a generalized Gibb's
Ensemble(GGE). We can also tune the initial states so that the final states are
exact Calabrese-Cardy (CC) state and special gCC states. The system in the CC
state thermalizes to a Gibb's ensemble. We derive closed-form analytic
expressions for the growth of entanglement entropy of subsystems consisting of
arbitrary number of disjoint intervals in CC state. We show that the
entanglement entropy of a single interval grows monotonically before
saturation. In case of certain gCC states, for particular charges, the
entanglement entropy of a single interval grows non-monotonically when the
effective chemical potential is increased beyond a critical value. We argue
that the non-monotonic growth of entanglement entropy is due to increase in
long range correlation and decrease in short range correlation at early times.
