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Subject[RFC][PATCH v6 0/7] Generic page pool & deferred freeing for system dmabuf heap
This series is starting to get long, so I figured I'd add a
short cover letter for context.

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.

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 86572223 ns 17314 ns/call
ion heap: alloc 4096 bytes 5000 times in 97442526 ns 19488 ns/call
dmabuf heap: alloc 1048576 bytes 5000 times in 196635057 ns 39327 ns/call
ion heap: alloc 1048576 bytes 5000 times in 357323629 ns 71464 ns/call
dmabuf heap: alloc 8388608 bytes 5000 times in 3165445534 ns 633089 ns/call
ion heap: alloc 8388608 bytes 5000 times in 3699591271 ns 739918 ns/call
dmabuf heap: alloc 33554432 bytes 5000 times in 13327402517 ns 2665480 ns/call
ion heap: alloc 33554432 bytes 5000 times in 15292352796 ns 3058470 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. This required pulling the fairly tightly knit
ttm_pool logic apart, but after many failed attmempts I think
I found a workable abstraction to split out shared logic.

So this series contains a new generic drm_page_pool helper
library, converts the ttm_pool to use it, and then adds the
dmabuf deferred freeing and adds support to the dmabuf system
heap to use both deferred freeing and the new drm_page_pool.

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



Cc: Daniel Vetter <>
Cc: Christian Koenig <>
Cc: Sumit Semwal <>
Cc: Liam Mark <>
Cc: Chris Goldsworthy <>
Cc: Laura Abbott <>
Cc: Brian Starkey <>
Cc: Hridya Valsaraju <>
Cc: Suren Baghdasaryan <>
Cc: Sandeep Patil <>
Cc: Daniel Mentz <>
Cc: Ørjan Eide <>
Cc: Robin Murphy <>
Cc: Ezequiel Garcia <>
Cc: Simon Ser <>
Cc: James Jones <>

John Stultz (7):
drm: Add a sharable drm page-pool implementation
drm: ttm_pool: Rename the ttm_pool_dma structure to ttm_pool_page_dat
drm: ttm_pool: Rework ttm_pool_free_page to allow us to use it as a
function pointer
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 | 145 ++++++++++
drivers/dma-buf/heaps/deferred-free-helper.h | 55 ++++
drivers/dma-buf/heaps/system_heap.c | 77 ++++-
drivers/gpu/drm/Kconfig | 5 +
drivers/gpu/drm/Makefile | 1 +
drivers/gpu/drm/page_pool.c | 220 +++++++++++++++
drivers/gpu/drm/ttm/ttm_pool.c | 278 ++++++-------------
include/drm/page_pool.h | 54 ++++
include/drm/ttm/ttm_pool.h | 23 +-
11 files changed, 639 insertions(+), 225 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


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