On Mon, Feb 10, 2020 at 02:20:10PM -0500, Tim Walker wrote: > -What Linux storage stack assumptions do we need to be aware of as we > develop these devices with drastically different performance > characteristics than traditional NAND? For example, what schedular or > device driver level changes will be needed to integrate NVMe HDDs? Right now the nvme driver unconditionally sets QUEUE_FLAG_NONROT (non-rational, i.e. ssd), on all nvme namespace's request_queue flags. We need the specification to define a capability bit or field associated with the namespace to tell the driver otherwise, then we can propogate that information up to the block layer. Even without that, an otherwise spec compliant HDD should function as an nvme device with existing software, but I would be interested to hear additional ideas or feature gaps with other protocols that should be considered in order to make an nvme hdd work well.
