[RESEND,v4,0/7] dma-buf: Performance improvements for system heap & a system-uncached implementation

Message

John Stultz Oct. 29, 2020, 12:16 a.m. UTC

Hey All,
  So just wanted to resend my last revision of my patch series
of performance optimizations to the dma-buf system heap.

This series reworks the system heap to use sgtables, and then
consolidates the pagelist method from the heap-helpers into the
CMA heap. After which the heap-helpers logic is removed (as it
is unused). I'd still like to find a better way to avoid some of
the logic duplication in implementing the entire dma_buf_ops
handlers per heap. But unfortunately that code is tied somewhat
to how the buffer's memory is tracked. As more heaps show up I
think we'll have a better idea how to best share code, so for
now I think this is ok.

After this, the series introduces an optimization that
Ørjan Eide implemented for ION that avoids calling sync on
attachments that don't have a mapping.

Next, an optimization to use larger order pages for the system
heap. This change brings us closer to the current performance
of the ION allocation code (though there still is a gap due
to ION using a mix of deferred-freeing and page pools, I'll be
looking at integrating those eventually).

Finally, a reworked version of my uncached system heap
implementation I was submitting a few weeks back. Since it
duplicated a lot of the now reworked system heap code, I
realized it would be much simpler to add the functionality to
the system_heap implementation itself.

While not improving the core allocation performance, the
uncached heap allocations do result in *much* improved
performance on HiKey960 as it avoids a lot of flushing and
invalidating buffers that the cpu doesn't touch often.

Feedback on these would be great!

thanks
-john

New in v4:
* Make sys_heap static (indirectly) Reported-by:
     kernel test robot <[e-mail]>
* Spelling fixes suggested by BrianS
* Make sys_uncached_heap static, as
    Reported-by: kernel test robot <[e-mail]>
* Fix wrong return value, caught by smatch
    Reported-by: kernel test robot <[e-mail]>
    Reported-by: Dan Carpenter <[e-mail]>
* Ensure we call flush/invalidate_kernel_vmap_range() in the
  uncached cases to try to address feedback about VIVT caches
  from Christoph
* Reorder a few lines as suggested by BrianS
* Avoid holding the initial mapping for the lifetime of the buffer
  as suggested by BrianS
* Fix a unlikely race between allocate and updating the dma_mask
  that BrianS noticed.

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

John Stultz (7):
  dma-buf: system_heap: Rework system heap to use sgtables instead of
    pagelists
  dma-buf: heaps: Move heap-helper logic into the cma_heap
    implementation
  dma-buf: heaps: Remove heap-helpers code
  dma-buf: heaps: Skip sync if not mapped
  dma-buf: system_heap: Allocate higher order pages if available
  dma-buf: dma-heap: Keep track of the heap device struct
  dma-buf: system_heap: Add a system-uncached heap re-using the system
    heap

 drivers/dma-buf/dma-heap.c           |  33 +-
 drivers/dma-buf/heaps/Makefile       |   1 -
 drivers/dma-buf/heaps/cma_heap.c     | 324 +++++++++++++++---
 drivers/dma-buf/heaps/heap-helpers.c | 270 ---------------
 drivers/dma-buf/heaps/heap-helpers.h |  53 ---
 drivers/dma-buf/heaps/system_heap.c  | 488 ++++++++++++++++++++++++---
 include/linux/dma-heap.h             |   9 +
 7 files changed, 747 insertions(+), 431 deletions(-)
 delete mode 100644 drivers/dma-buf/heaps/heap-helpers.c
 delete mode 100644 drivers/dma-buf/heaps/heap-helpers.h