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* [Intel-gfx] [RFC 0/3] Waitboost drm syncobj waits
@ 2023-02-09 15:43 Tvrtko Ursulin
  2023-02-09 15:43 ` [Intel-gfx] [RFC 1/3] dma-fence: Track explicit waiters Tvrtko Ursulin
                   ` (4 more replies)
  0 siblings, 5 replies; 6+ messages in thread
From: Tvrtko Ursulin @ 2023-02-09 15:43 UTC (permalink / raw)
  To: Intel-gfx, dri-devel

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

In i915 we have this concept of "wait boosting" where we give a priority boost
for instance to fences which are actively waited upon from userspace. This has
it's pros and cons and can certainly be discussed at lenght. However fact is
some workloads really like it.

Problem is that with the arrival of drm syncobj and a new userspace waiting
entry point it added, the waitboost mechanism was bypassed. Hence I cooked up
this mini series really (really) quickly to see if some discussion can be had.

It adds a concept of "wait count" to dma fence, which is incremented for every
explicit dma_fence_enable_sw_signaling and dma_fence_add_wait_callback (like
dma_fence_add_callback but from explicit/userspace wait paths).

Individual drivers can then inspect this via dma_fence_wait_count() and decide
to wait boost the waits on such fences.

Again, quickly put together and smoke tested only - no guarantees whatsoever and
I will rely on interested parties to test and report if it even works or how
well.

Tvrtko Ursulin (3):
  dma-fence: Track explicit waiters
  drm/syncobj: Mark syncobj waits as external waiters
  drm/i915: Waitboost external waits

 drivers/dma-buf/dma-fence.c         | 102 ++++++++++++++++++++--------
 drivers/gpu/drm/drm_syncobj.c       |   6 +-
 drivers/gpu/drm/i915/i915_request.c |  13 +++-
 include/linux/dma-fence.h           |  14 ++++
 4 files changed, 101 insertions(+), 34 deletions(-)

-- 
2.34.1


^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2023-02-09 16:39 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-02-09 15:43 [Intel-gfx] [RFC 0/3] Waitboost drm syncobj waits Tvrtko Ursulin
2023-02-09 15:43 ` [Intel-gfx] [RFC 1/3] dma-fence: Track explicit waiters Tvrtko Ursulin
2023-02-09 15:43 ` [Intel-gfx] [RFC 2/3] drm/syncobj: Mark syncobj waits as external waiters Tvrtko Ursulin
2023-02-09 15:43 ` [Intel-gfx] [RFC 3/3] drm/i915: Waitboost external waits Tvrtko Ursulin
2023-02-09 16:18 ` [Intel-gfx] ✗ Fi.CI.SPARSE: warning for Waitboost drm syncobj waits Patchwork
2023-02-09 16:39 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork

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