[Intel-gfx] [PATCH v10] drm/i915: Squash repeated awaits on the same fence

[Chris Wilson]

On Fri, Apr 28, 2017 at 08:41:36AM +0100, Chris Wilson wrote:
> Track the latest fence waited upon on each context, and only add a new
> asynchronous wait if the new fence is more recent than the recorded
> fence for that context. This requires us to filter out unordered
> timelines, which are noted by DMA_FENCE_NO_CONTEXT. However, in the
> absence of a universal identifier, we have to use our own
> i915->mm.unordered_timeline token.
> 
> v2: Throw around the debug crutches
> v3: Inline the likely case of the pre-allocation cache being full.
> v4: Drop the pre-allocation support, we can lose the most recent fence
> in case of allocation failure -- it just means we may emit more awaits
> than strictly necessary but will not break.
> v5: Trim allocation size for leaf nodes, they only need an array of u32
> not pointers.
> v6: Create mock_timeline to tidy selftest writing
> v7: s/intel_timeline_sync_get/intel_timeline_sync_is_later/ (Tvrtko)
> v8: Prune the stale sync points when we idle.
> v9: Include a small benchmark in the kselftests
> v10: Separate the idr implementation into its own compartment.

Before you complain, I haven't yet attempted to refactor the kselftests
to avoid deep indentation.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre