The OpenStack and Linux developer communities compared
The kernel has roughly twice as fast of a release cycle as OpenStack. In the kernel's case, there are roughly 2-3 month release cycles containing a two week merge period with six to ten week of stabilization work. OpenStack's cycle is six months, made up by a four week planning window, 14 weeks of code merger, and six weeks dedicated to stabilization. The result? Faster releases for the kernel, but perhaps less significant changes per release.