Re: [RFC PATCH 1/5] block, ioprio: include caching advice via ionice

Jeff Moyer
2014-10-29T19:02:50Z

"Jason B. Akers" <jason.b.akers@intel.com> writes:

> From: Dan Williams <dan.j.williams@intel.com>
>
> Steal one unused bit from the priority class and two bits from the
> priority data, to implement a 3 bit cache-advice field. Similar to the
> page cache advice from fadvise() these hints are meant to be consumed
> by hybrid drives. Solid State Hyrbid-Drives, as defined by the SATA-IO
> Specification, implement up to a 4-bit cache priority that can be
> specified along with a FPDMA command.

ionice is about setting an I/O scheduling class for a *process*. So,
unless I've missed something, this does not seem like the right
interface for passing I/O hints.

You mention fadvise hints, which sounds like a good fit (and madvise
would be equally interesting), but I don't see where you've wired them
up in this patch set. Did I miss it?

Cheers,
Jeff