The Exynos 5 Octa is the “first” octa core processor, but it was never a true octa core. While it did in fact have eight separate cores, it could only use four at a time by design. It would either use the four A15 cores, or the four A7 cores for small tasks. This would make it a dual-quad core processor, and while it isn’t true octa core, it’s still a good way to save energy.
However, Samsung has now added Heterogeneous Multi-Processing (HMP) to the Exynos 5 Octa, which allows for all eight cores to be used at the same time. Instead of allocating small tasks to the A15 cores during intensive tasks like video games, it will allocate the A15 cores to the processor intensive threads and the A7 cores for the small processes. Not only does it allow for more power for any processor intensive task, it also prevents lag when many tasks are running.
The only possible issue here would be battery life. Using all eight cores at once could really run the battery dry fast. But Samsung is known for decent battery life in their products, and this new system can be heavily optimized to save battery when needed.
It wasn’t really explained whether this would come only with new Exynos 5 Octa chips, or if it would be a kernel/driver change for current Octa chips. So, we don’t know whether current Octa users will ever get to see HMP. Samsung did state that we will be seeing this technology in Q4 of 2013, so it’ll be soon. Will it come to the Galaxy Note 3? We hope so.