For a closed system: If we define a quasi-static locus (process) as an ordered and dense succession of equilibrium states in the thermodynamic configuration space. Then we define a reversible process as one in which no entropy is generated. Then it is clear that there are some quasi-static loci which are not necessarily reversible simply because there is entropy generation along these loci. However, is it necessary that every reversible process has to be coincident with a quasi-static process? I think another statement for the same question, is it possible to have no entropy generation during a non-equilibrium process?