[PATCH v2 0/4] Write-hint for FS journal

Keith Busch
2019-01-28T23:24:24Z

On Mon, Jan 28, 2019@04:47:09AM -0800, Jan Kara wrote:
> On Fri 25-01-19 09:23:53, Keith Busch wrote:
> > On Wed, Jan 09, 2019@09:00:57PM +0530, Kanchan Joshi wrote:
> > > Towards supporing write-hints/streams for filesystem journal.
> > >
> > > Here is the v1 patch for background -
> > > https://marc.info/?l=linux-fsdevel&m=154444637519020&w=2
> > >
> > > Changes since v1:
> > > - introduce four more hints for in-kernel use, as recommended by Dave chinner
> > > & Jens axboe. This isolates kernel-mode hints from user-mode ones.
> >
> > The nvme driver disables streams if the controller doesn't support
> > BLK_MAX_WRITE_HINT number of streams, so this series breaks the feature
> > for controllers that only support up to 4.
>
> Right. Do you know if there are such controllers? Or are you just afraid
> that there could be?

I've asked around, and the concensus I received is all currently support
at least 8, but they couldn't say if that would be true for potential
lower budget products. Can we implement a reasonable fallback to use
what's available?