[PATCH] nvme: enable FDP support

[Kanchan Joshi]

On Mon, May 13, 2024 at 2:04 AM Viacheslav Dubeyko <slava at dubeyko.com> wrote:
>
>
>
> > On May 10, 2024, at 4:40 PM, Kanchan Joshi <joshi.k at samsung.com> 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.
> >
> > Fetches the placement-identifiers (plids) if the device supports FDP.
> > And map the incoming write-hints to plids.
> >
>
>
> Great! Thanks for sharing  the patch.
>
> Do  we have documentation that explains how, for example, kernel-space
> file system can work with block layer to employ FDP?

This is primarily for user driven/exposed hints. For file system
driven hints, the scheme is really file system specific and therefore,
will vary from one to another.
F2FS is one (and only at the moment) example. Its 'fs-based' policy
can act as a reference for one way to go about it.