If the source of the current accelerating expansion of the universe is a positive cosmological constant, Banks and Fischler argued that there exists an upper limit of the total number of e-foldings of inflation. We further elaborate on the upper limit in the sense of viewing the cosmological horizon as the boundary of a cavity and of the holographic D-bound in a de Sitter space. Assuming a simple evolution model of inflation, we obtain an expression of the upper limit in terms of the cosmological constant, the energy density of the inflaton when the inflation starts, the energy density as the inflation ends and reheating temperature. We discuss how the upper limit is modified in the different evolution models of the universe. The holographic D-bound gives a higher upper limit than the entropy threshold in the cavity. For the most extreme case where the initial energy density of inflation is as high as the Planck energy, and the reheating temperature is as low as the energy scale of nucleosynthesis, the D-bound gives the upper limit as 146 and the entropy threshold as 122. For a reasonable assumption in the simplest cosmology, the holographic D-bound leads to a value of about 85, while the cavity model gives a value of around 65 for the upper limit, which is close to the value needed to solve the flatness problem and the horizon problem in the hot big bang cosmology.