Re: [PATCHv10 9/9] scsi: set permanent stream count in block limits

[Keith Busch <kbusch@kernel.org>]

On Wed, Oct 30, 2024 at 04:45:56PM +0100, Christoph Hellwig wrote:
> On Wed, Oct 30, 2024 at 09:41:39AM -0600, Keith Busch wrote:
> > On Wed, Oct 30, 2024 at 05:55:26AM +0100, Christoph Hellwig wrote:
> > > On Tue, Oct 29, 2024 at 10:22:56AM -0600, Keith Busch wrote:
> > > 
> > > > No need to create a new fcntl. The people already testing this are
> > > > successfully using FDP with the existing fcntl hints. Their applications
> > > > leverage FDP as way to separate files based on expected lifetime. It is
> > > > how they want to use it and it is working above expectations. 
> > > 
> > > FYI, I think it's always fine and easy to map the temperature hits to
> > > write streams if that's all the driver offers.  It loses a lot of the
> > > capapilities, but as long as it doesn't enforce a lower level interface
> > > that never exposes more that's fine.
> > 
> > But that's just the v2 from this sequence:
> > 
> > https://lore.kernel.org/linux-nvme/20240528150233.55562-1-joshi.k@samsung.com/
> > 
> > If you're okay with it now, then let's just go with that and I'm happy
> > continue iterating on the rest separately. 
> 
> That's exactly what I do not want - it takes the temperature hints
> and force them into the write streams down in the driver 

What??? You said to map the temperature hints to a write stream. The
driver offers that here. But you specifically don't want that? I'm so
confused.

> with no way to make actually useful use of the stream separation.

Have you tried it? The people who actually do easily demonstrate it is
in fact very useful.