Re: remove a few uses of ->queuedata
On Sat, May 9, 2020 at 1:24 AM Christoph Hellwig <hch(a)lst.de> wrote:
On Fri, May 08, 2020 at 11:04:45AM -0700, Dan Williams wrote:
> On Fri, May 8, 2020 at 9:16 AM Christoph Hellwig <hch(a)lst.de> wrote:
> >
> > Hi all,
> >
> > various bio based drivers use queue->queuedata despite already having
> > set up disk->private_data, which can be used just as easily. This
> > series cleans them up to only use a single private data pointer.
>
> ...but isn't the queue pretty much guaranteed to be cache hot and the
> gendisk cache cold? I'm not immediately seeing what else needs the
> gendisk in the I/O path. Is there another motivation I'm missing?
->private_data is right next to the ->queue pointer, pat0 and part_tbl
which are all used in the I/O submission path (generic_make_request /
generic_make_request_checks). This is mostly a prep cleanup patch to
also remove the pointless queue argument from ->make_request - then
->queue is an extra dereference and extra churn.
Ah ok. If the changelogs had been filled in with something like "In
preparation for removing @q from make_request_fn, stop using
->queuedata", I probably wouldn't have looked twice.
For the nvdimm/ driver updates you can add:
Reviewed-by: Dan Williams <dan.j.williams(a)intel.com>
...or just let me know if you want me to pick those up through the nvdimm tree.