Qnap TS-221 NAS Review
NVIDIA’s Project Kal-El processor implements a novel new Variable Symmetric Multiprocessing (vSMP) technology. Not previously disclosed publicly, vSMP includes a fifth CPU core (the “Companion” core) built using a special low power silicon process that executes tasks at low frequency for active standby mode, music playback, and even video playback. The four main “quad” cores are built using a standard silicon process to reach higher frequencies, while consuming lower power than dual core solutions for many tasks. All five CPU cores are identical ARM Cortex A9 CPUs, and are individually enabled and disabled (via aggressive power gating) based on the work load. The “Companion” core is OS transparent, unlike current Asynchronous SMP architectures, meaning the OS and applications are not aware of this core, but automatically take advantage of it. This strategy saves significant software efforts and new coding requirements.
In addition to vSMP technology, it’s important to remember that more cores are better for power management than fewer cores. As an example, quad core CPUs deliver lower power at all performance points compared to dual core CPUs. The reason is that four cores can run at a lower frequency, and hence lower voltage when processing the same amount of work as a dual core CPU. Since power is proportional to the square of the voltage, the overall CPU power can be significantly less – and still complete the same amount of work.