The Linux kernel to now hasn’t provided proper support for NVMe power-savings via APST, Autonomous Power State Transitions, but it’s coming.
Linux kernel developer Andy Lutomirski has posted a set of patches for implementing power-savings support for NVM Express storage devices. He commented on the patch series that touches around 200 lines of code, “On my Samsung 950, this means we enter state 3 (70mW, 0.5ms entry latency, 5ms exit latency) after 275ms and state 4 (5mW, 2ms entry latency, 22ms exit latency) after 1200ms. I have the default max latency set to 25ms.”