[EARLY RFC][PATCH 0/4] dmabuf pools infrastructure (destaging ION)

[John Stultz]

On Fri, Feb 22, 2019 at 9:24 AM John Stultz <john.stultz at linaro.org> wrote:
>
> On Fri, Feb 22, 2019 at 8:55 AM Andrew F. Davis <afd at ti.com> wrote:
> > On 2/21/19 1:40 AM, John Stultz wrote:
> > > Here is a very early peek at my dmabuf pools patchset, which
> > > tries to destage a fair chunk of ION functionality.
> > >
> > > This build and boots, but I've not gotten to testing the actual
> > > pool devices yet (need to write some kselftests)! I just wanted
> > > some early feedback on the overall direction.
> > >
> > > The patchset implements per-pool devices (extending my ion
> > > per-heap devices patchset from last week), which can be opened
> > > directly and then an ioctl is used to allocate a dmabuf from the
> > > pool.
> > >
> > > The interface is similar, but simpler then IONs, only providing
> > > an ALLOC ioctl.
> > >
> > > Also, I've only destaged the system/system-contig and cma pools,
> > > since the ION carveout and chunk heaps depended on out of tree
> > > board files to initialize those heaps. I'll leave that to folks
> > > who are actually using those heaps.
> > >
> > > Let me know what you think!
> > >
> >
> > +1
> >
> > Was this source not pulled from -next, I have some fixes in next that I
> > don't see in this code, so I won't review the code itself just yet (it
> > is and early RFC after all). For the concept itself I have a couple
> > small suggestions:
>
> Oh, no, I've missed those. I was working off -rc7. I'll try to
> re-integrate them in.
>
> > I'm not sure I like the name. "Pool" in the context of DMA-BUF feels
> > like it means something else, like some new feature of DMA-BUFs
> > exporters/importers can use for making buffer pools. How about just keep
> > the "heap" terminology to prevent too much re-wording. Maybe just call
> > this dma-buf/heaps/ ?
>
> The name changing was mostly as Laura noted that the term heap has
> caused confusion historically. I'm not really particular, and I do
> worry about the naming overlap between dmabuf-pools and the pagepool
> code was problematic. Due to that overlap, renaming things back will
> be a small chore, but I've got only myself to blame there :)

Ok, I've renamed things back to heaps, and updated the patches here
(sorry, I didn't rename the git branch :):
  kernel: https://git.linaro.org/people/john.stultz/android-dev.git/log/?h=dev/dma-buf-pools
  userland: https://android-review.googlesource.com/c/device/linaro/hikey/+/909436

I'll get to integrating your changes in -next, and see about splitting
the page pool/deferred freeing logic out to the end here soon.

thanks
-john