Re: [PATCH v7 1/3] nvme: enable FDP support

Bart Van Assche
2024-10-02T18:37:21Z

On 9/30/24 11:13 AM, Kanchan Joshi wrote:
> Flexible Data Placement (FDP), as ratified in TP 4146a, allows the host
> to control the placement of logical blocks so as to reduce the SSD WAF.
>
> Userspace can send the data lifetime information using the write hints.
> The SCSI driver (sd) can already pass this information to the SCSI
> devices. This patch does the same for NVMe.
>
> Fetch the placement-identifiers if the device supports FDP.
> The incoming write-hint is mapped to a placement-identifier, which in
> turn is set in the DSPEC field of the write command.

Is the description of this patch correct? The above description suggests
that FDP information is similar in nature to SCSI data lifetime
information. I don't think that's correct.

Thanks,

Bart.