* Visualize texture system starts out in an inactive state until a command is issued, avoiding overhead of tracking views and scene textures, saving 1.4% on the render thread.
* Visualization overhead eliminated for views besides the one currently being visualized.
* Support for visualization of textures from scene captures, via "view=N" option (specifying the unique ID of the view), with "view=?" displaying a list of views for reference.
* Improved visualization for cube maps. PIP uses 2:1 aspect for the longitudinal render to match resource viewer display, and pixel perfect option shows tiled flat cube map faces (actual pixels) rather than running a projection.
* Padding for scene or screen pass textures is removed in the visualization -- the padding otherwise shows up as garbage or blank space.
To remove scene texture padding, it's necessary to add a field to RDG textures to provide an option to track the viewport sizes that were rendered for a given texture. If not set, the assumption is the whole texture was rendered. The field is set for FSceneTextures and FScreenPassTexture, covering the vast majority of cases, plus the denoiser was spot fixed -- worst case if any other cases are missed, you still see the padding. You can tell padding was present when visualizing by contrasting the texture size with the viewport size.
Padding was always a potential issue for the visualizer, but is exacerbated by scene captures, as the padded scene textures are set to a size that's a union of the main view and any scene captures. Padding is also exacerbated by dynamic resolution scaling, as the buffers will be padded to the maximum resolution. For example, a cube map rendering at 512x512 will have 93% of the pixel area as padding if the front buffer is at 1440p, or the default dynamic resolution setup will have 70% of the pixels as padding at minimum res.
#rb Jason.Nadro
[CL 31160232 by jason hoerner in ue5-main branch]
Significant refactor of RHI command list management and submission, and RHI breadcrumbs / RenderGraph (RDG) scopes, to allow for parallel translation of most RHI command lists.
See individual changelists in //UE5/Dev-ParallelRendering for details. A summary of the changes is as follows:
This work's primary goal was to allow as many RHI command lists as possible to be parallel translated, to make more efficient use of many-core systems. To achieve this:
- The submission code paths for the immediate and parallel RHI command lists have been merged into a single function: FRHICommandListExecutor::Submit().
- A "dispatch thread" (which is simply a series of chained task graph tasks) is used to decide which command lists are batched together in a single parallel translate job.
- Individual command lists can disable parallel translate, which forces them to be executed on the RHI thread. This happens automatically if an RHI command list performs an operation that is not thread safe (e.g. buffer lock, or low-level resource transition).
One of the primary blockers for parallel translation was the RHI breadcrumb system, and the way RDG builds scopes. This was also refactored to remove these limitations:
- RDG could only push/pop events on the immediate command list, which resulted in parallel and immediate work being interleaved, breaking any opportunity for parallelism.
- Platform RHI implementations of breadcrumbs (e.g. in D3D12 RHI) was not correct across multiple RHI contexts. Push/pop operations aren't necessarily balanced within any one RHI context given that RDG builds "parallel pass sets" containing arbitrary ranges of renderer passes.
A summary of the new RHI breadcrumb system is as follows:
- A tree of breadcrumb nodes is built by the render thread and RDG. Each node contains the node name, and pointers to the parent and next nodes. When fully built, the nodes form a depth-first linked list which is used for traversing the tree for GPU crash debugging.
- The memory for breadcrumb nodes is provided by ref-counted allocator objects. These allocators are pipelined through the RHI, allowing the platform RHI implementation to extend their lifetime for GPU crash debugging purposes.
- RHIPushEvent / RHIPopEvent have been removed, replaced with RHIBeginBreadcrumbGPU / RHIEndBreadcrumbGPU. Platform RHIs implement these functions to perform GPU immediate writes using the unique ID of each node, for tracking GPU progress.
- Format string arguments are captured by-value to remove the cost of string formatting while building the breadcrumb tree. String formatting only occurs when the actual formatted string is required (e.g. during GPU crash breadcrumb stack traversal, or when calling platform GPU profiling APIs).
RenderGraph scopes have been simplified:
- The separate scope trees / arrays of ops have been combined. There is now a single tree of RDG scopes containing all types.
- Each RDG pass holds a pointer to the scope it was created under.
- BeginCPU / EndCPU is called on each RDG scope as the various RDG threads enter / exit them. This allows us to mark-up each worker thread with the relevant Unreal Insights scopes.
Other changes include:
- Fixes for bugs uncovered when parallel translate was enabled.
- Adjusted platform affinities necessary due to the new layout of thread tasks in the renderer.
- Refactored RHI draw call stats to better fit the new pipeline design.
#rb jeannoe.morissette, zach.bethel
#jira UE-139543
[CL 30973133 by Luke Thatcher in ue5-main branch]
* Skip contents of Begin/EndUAVOverlap when GRHIValidationEnabled is false, avoiding expensive GatherPassUAVsForOverlapValidation call, saving around 1.4% frame wide. Lower level function does nothing when validation isn't enabled.
* Optimize trivial RDG event names with no format specifiers. Detects at compile time that there are no variadic parameters and calls a non-variadic version of the constructor, which references the string instead of generating a dynamically allocated copy through FCString::GetVarArgs. Covers around 40% of RDG event names in my test case, saving around 1.2% frame wide.
#rnx
#rb mihnea.balta
[CL 30781413 by jason hoerner in ue5-main branch]
- Subresource state tracking manipulates less data by always using pointers instead of copying full states.
- Offloaded pooled texture / buffer allocations to an async task.
- Removed dependency between pooled resource allocations and collecting resource barriers. The 'finalize' phase now gathers both first and last barriers for a resource.
- Refactors RDG allocator implementation to make things simpler.
- Moved async tasks within RDG to use the setup task API.
- Moved culling into the async setup queue.
[CL 30774932 by zach bethel in ue5-main branch]
* Add QueueCommitReservedBuffer() to FRDGBuilder
* Add GetCommittedSize() to FRDGPooledBuffer, to query the physical size of the buffer
* Change ResizeBufferIfNeeded() to issue a commit operation instead of copying when possible
* Add r.Nanite.Streaming.ReservedResources CVar (default: false) to allocate Nanite ClusterPageData.DataBuffer as a reserved resource of maximum size, which is committed in ResizeBufferIfNeeded()
Based on implementation by Zach Bethel.
#rb Zach.Bethel
[CL 29626308 by yuriy odonnell in ue5-main branch]
