[PATCH v8 0/5] Generic page pool & deferred freeing for system dmabuf heap

[John Stultz]

Apologies for letting so much time pass since the last revision!

The point of this series is trying to add both deferred-freeing
logic as well as a page pool to the DMA-BUF system heap to improve
allocation performance.

This is desired, as the combination of deferred freeing along
with the page pool allows us to offload page-zeroing out of
the allocation hot path. This was done originally with ION
and this patch series allows the DMA-BUF system heap to match
ION's system heap allocation performance in a simple
microbenchmark [1] (ION re-added to the kernel for comparision,
running on an x86 vm image):

./dmabuf-heap-bench -i 0 1 system
Testing dmabuf system vs ion heaptype 0 (flags: 0x1)
---------------------------------------------
dmabuf heap: alloc 4096 bytes 5000 times in 88092722 ns          17618 ns/call
ion heap:    alloc 4096 bytes 5000 times in 103043547 ns         20608 ns/call
dmabuf heap: alloc 1048576 bytes 5000 times in 252416639 ns      50483 ns/call
ion heap:    alloc 1048576 bytes 5000 times in 358190744 ns      71638 ns/call
dmabuf heap: alloc 8388608 bytes 5000 times in 2854351310 ns     570870 ns/call
ion heap:    alloc 8388608 bytes 5000 times in 3676328905 ns     735265 ns/call
dmabuf heap: alloc 33554432 bytes 5000 times in 13208119197 ns   2641623 ns/call
ion heap:    alloc 33554432 bytes 5000 times in 15306975287 ns   3061395 ns/call


Daniel didn't like earlier attempts to re-use the network
page-pool code to achieve this, and suggested the ttm_pool be
used instead, so this series pulls the page pool functionality
out of the ttm_pool logic and creates a generic page pool
that can be shared.

New in v7 (never submitted):
* Reworked how I integrated the page pool with the ttm logic
  to use container of to avoid allocating structures per page. 

New in v8:
* Due to the dual license requirement from Christian König
  I completely threw away the earlier shared page pool
  implementation (which had evolved from ion code), and
  rewrote it using just the ttm_pool logic. My apologies
  for any previously reviewed issues that I've reintroduced
  in doing so.

Input would be greatly appreciated. Testing as well, as I don't
have any development hardware that utilizes the ttm pool.

thanks
-john

[1] https://android.googlesource.com/platform/system/memory/libdmabufheap/+/refs/heads/master/tests/dmabuf_heap_bench.c

Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: Christian Koenig <christian.koenig@xxxxxxx>
Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
Cc: Liam Mark <lmark@xxxxxxxxxxxxxx>
Cc: Chris Goldsworthy <cgoldswo@xxxxxxxxxxxxxx>
Cc: Laura Abbott <labbott@xxxxxxxxxx>
Cc: Brian Starkey <Brian.Starkey@xxxxxxx>
Cc: Hridya Valsaraju <hridya@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Sandeep Patil <sspatil@xxxxxxxxxx>
Cc: Daniel Mentz <danielmentz@xxxxxxxxxx>
Cc: Ørjan Eide <orjan.eide@xxxxxxx>
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
Cc: Simon Ser <contact@xxxxxxxxxxx>
Cc: James Jones <jajones@xxxxxxxxxx>
Cc: linux-media@xxxxxxxxxxxxxxx
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx

John Stultz (5):
  drm: Add a sharable drm page-pool implementation
  drm: ttm_pool: Rework ttm_pool to use drm_page_pool
  dma-buf: heaps: Add deferred-free-helper library code
  dma-buf: system_heap: Add drm pagepool support to system heap
  dma-buf: system_heap: Add deferred freeing to the system heap

 drivers/dma-buf/heaps/Kconfig                |   5 +
 drivers/dma-buf/heaps/Makefile               |   1 +
 drivers/dma-buf/heaps/deferred-free-helper.c | 138 ++++++++++++
 drivers/dma-buf/heaps/deferred-free-helper.h |  55 +++++
 drivers/dma-buf/heaps/system_heap.c          |  47 +++-
 drivers/gpu/drm/Kconfig                      |   5 +
 drivers/gpu/drm/Makefile                     |   2 +
 drivers/gpu/drm/page_pool.c                  | 214 +++++++++++++++++++
 drivers/gpu/drm/ttm/ttm_pool.c               | 156 +++-----------
 include/drm/page_pool.h                      |  65 ++++++
 include/drm/ttm/ttm_pool.h                   |   6 +-
 11 files changed, 557 insertions(+), 137 deletions(-)
 create mode 100644 drivers/dma-buf/heaps/deferred-free-helper.c
 create mode 100644 drivers/dma-buf/heaps/deferred-free-helper.h
 create mode 100644 drivers/gpu/drm/page_pool.c
 create mode 100644 include/drm/page_pool.h

-- 
2.25.1