Am 07.07.21 um 09:14 schrieb Christoph Hellwig:
On Wed, Jul 07, 2021 at 09:10:26AM +0200, Christian K??nig wrote:
Well, the original code all this is based on already had the comment that
this really belong into the page allocator.
The key point is traditionally only GPUs used uncached and write-combined
memory in such large quantities that having a pool for them makes sense.
Because of this we had this separately to reduce the complexity in the page
allocator to handle another set of complexity of allocation types.
For the upside, for those use cases it means huge performance improvements
for those drivers. See the numbers John provided in the cover letter.
But essentially at least I would be totally fine moving this into the page
allocator, but moving it outside of TTM already helps with this goal. So
this patch set is certainly a step into the right direction.
Unless I'm badly misreading the patch and this series there is nothing
about cache attributes in this code. It just allocates pages, zeroes
them, eventually hands them out to a consumer and registers a shrinker
for its freelist.
If OTOH it actually dealt with cachability that should be documented
in the commit log and probably also the naming of the implementation.
Mhm, good point. In this case all left is the clearing overhead from the
allocation hot path to the free path and I'm not really sure why the
core page allocator shouldn't do that as well.
Regards,
Christian.
