Re: [PATCH v9 0/5] Generic page pool & deferred freeing for system dmabuf hea

[Christian König]

Am 30.06.21 um 03:34 schrieb John Stultz:
> After an unfortunately long pause (covid work-schedule burnout),
> I wanted to revive and resubmit this series.
>
> As before, the point of this series is trying to add both a page
> pool as well as deferred-freeingto the DMA-BUF system heap to
> improve allocation performance (so that it can match or beat the
> old ION system heaps performance).
>
> The combination of the page pool along with deferred freeing
> 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 79314244 ns          15862 ns/call
> ion heap:    alloc 4096 bytes 5000 times in 107390769 ns         21478 ns/call
> dmabuf heap: alloc 1048576 bytes 5000 times in 259083419 ns      51816 ns/call
> ion heap:    alloc 1048576 bytes 5000 times in 340497344 ns      68099 ns/call
> dmabuf heap: alloc 8388608 bytes 5000 times in 2603105563 ns     520621 ns/call
> ion heap:    alloc 8388608 bytes 5000 times in 3613592860 ns     722718 ns/call
> dmabuf heap: alloc 33554432 bytes 5000 times in 12212492979 ns   2442498 ns/call
> ion heap:    alloc 33554432 bytes 5000 times in 14584157792 ns   2916831 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 v9:
> * Tried to address Christian König's feedback on the page pool
>    changes (Kerneldoc, static functions, locking issues, duplicative
>    order tracking)
> * Fix up Kconfig dependency issue as Reported-by:
>    kernel test robot <lkp@xxxxxxxxx>
> * Fix compiler warning Reported-by:
>    kernel test robot <lkp@xxxxxxxxx>
>
> I know Christian had some less specific feedback on the deferred free
> work that I'd like to revisit, but I wanted to restart the discussion
> with this new series, rather then trying to dregdge up and reply to
> a ~4mo old thread.

I was already wondering where this was left :)

The kernel test robot pointed out quite a number of bugs. I suggest to 
fix those first and then take a look at my comments on patch #1.

Regards,
Christian.

> 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://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fandroid.googlesource.com%2Fplatform%2Fsystem%2Fmemory%2Flibdmabufheap%2F%2B%2Frefs%2Fheads%2Fmaster%2Ftests%2Fdmabuf_heap_bench.c&amp;data=04%7C01%7Cchristian.koenig%40amd.com%7C6d982c8c584d4fb914f208d93b673549%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637606136750178732%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=iNOuK8umbpkC4oYSM%2FaM3Ybx45FUWQsoRxPDjznBw70%3D&amp;reserved=0
>
> 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: system_heap: Add drm pagepool support to system heap
>    dma-buf: heaps: Add deferred-free-helper library code
>    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          |  46 ++-
>   drivers/gpu/drm/Kconfig                      |   4 +
>   drivers/gpu/drm/Makefile                     |   2 +
>   drivers/gpu/drm/page_pool.c                  | 297 +++++++++++++++++++
>   drivers/gpu/drm/ttm/ttm_pool.c               | 167 ++---------
>   include/drm/page_pool.h                      |  68 +++++
>   include/drm/ttm/ttm_pool.h                   |  14 +-
>   11 files changed, 643 insertions(+), 154 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