RE: [PATCH v7 0/3] FDP and per-io hints

Javier Gonzalez
2024-10-14T07:02:22Z

> -----Original Message-----
> From: Christoph Hellwig <hch@lst.de>
> Sent: Monday, October 14, 2024 8:21 AM
> To: Jens Axboe <axboe@kernel.dk>
> Cc: Christoph Hellwig <hch@lst.de>; Javier Gonzalez <javier.gonz@samsung.com>;
> Keith Busch <kbusch@kernel.org>; Martin K. Petersen
> <martin.petersen@oracle.com>; Kanchan Joshi <joshi.k@samsung.com>;
> hare@suse.de; sagi@grimberg.me; brauner@kernel.org; viro@zeniv.linux.org.uk;
> jack@suse.cz; jaegeuk@kernel.org; bcrl@kvack.org; dhowells@redhat.com;
> bvanassche@acm.org; asml.silence@gmail.com; linux-nvme@lists.infradead.org;
> linux-fsdevel@vger.kernel.org; io-uring@vger.kernel.org; linux-
> block@vger.kernel.org; linux-aio@kvack.org; gost.dev@samsung.com;
> vishak.g@samsung.com
> Subject: Re: [PATCH v7 0/3] FDP and per-io hints
>
> On Fri, Oct 11, 2024 at 11:08:26AM -0600, Jens Axboe wrote:
> >
> > I think that last argument is a straw man - for any kind of interface
> > like this, we've ALWAYS just had the rule that any per-whatever
> > overrides the generic setting.
>
> And exactly that is the problem. For file systems we can't support
> that sanely. So IFF you absolutely want the per-I/O hints we need
> an opt in by the file operations. I've said that at least twice
> in this discussion before, but as everyone likes to have political
> discussions instead of technical ones no one replied to that.

Is it a way forward to add this in a new spin of the series - keeping the
temperature mapping on the NVMe side?

If not, what would be acceptable for a first version, before getting into adding
a new interface to expose agnostic hints?