Frame looping fix#6
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olehkuznetsov merged 5 commits intoJun 25, 2026
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This CL introduces a robust state-restoration mechanism for Vulkan frame
looping to resolve deadlocks caused by fence state drift between loop
iterations (e.g., in Fortnite).
To keep the core framework clean and avoid intrusive changes to the
generic FileProcessor class, a "dual-capture" architecture is introduced:
1. For N = 1 (looping Frame 1): Fence states are captured at the end of
the setup phase via the consumer's ProcessStateEndMarker().
2. For N > 1 (looping Frame N): Fence states are captured immediately at
the Frame N boundary via the decoder's OnLoopStart() event.
To ensure stability, the consumer waits for all Vulkan devices to be idle
(reusing the inherited WaitDevicesIdle() helper) before querying and
storing the initial fence states.
At the loop boundary, we perform a spec-compliant, highly optimized fixup:
- Fences that drifted from UNSIGNALED -> SIGNALED are collected in
'fences_to_reset' and reset back to UNSIGNALED via vkResetFences.
- Fences that drifted from SIGNALED -> UNSIGNALED are collected in
'fences_to_signal' and synthetically signaled via vkQueueSubmit (without
any redundant reset calls).
All redundant logging overrides in the frame loop consumer have been
purged to keep the implementation minimal and efficient.
This CL resolves a SIGSEGV crash occurring during the final iteration of
Vulkan frame looping, particularly on traces with frequent descriptor pool
resets.
Problem: Asymmetric Skipping of Resource Lifecycle
- To optimize repetitions, the frame loop consumer skips resource
creations/allocations (e.g., descriptor sets). However, it previously
did NOT skip destructions/resets (like vkResetDescriptorPool) during the
final iteration, in an attempt to clean up.
- This created a fatal asymmetry: at the start of the final iteration,
replayed pool resets would execute and destroy the sets, but the
subsequent allocation calls in the frame would be skipped.
- This resulted in invalid/null descriptor set handles being passed to draw
calls during the final iteration, causing a driver-level SIGSEGV.
Fix: Symmetric Skipping
- Removed the `!IsFinalIteration()` constraint from descriptor pool
and set destructions/resets.
- We now symmetrically skip destructions/resets throughout the entire
looping range, including the final iteration.
- This keeps the reused resources alive and valid on the GPU until the
end of the replay. Since the replay process exits shortly after, the
OS/driver safely cleans up all leaked resources.
Tested:
- Verified that traces with frequent pool resets now loop successfully
without crashing on the second (final) iteration.
Add vkCreateCommandPool to the generated frame-looping overrides so that command pools created within the loop range are correctly tracked and subsequently destroyed on the final iteration of the loop. Also update the manual VulkanReplayFrameLoopConsumer override to delegate to the generated base class version to ensure proper handle tracking, while maintaining the necessary command buffer reset flag modifications. TAG=agy CONV=a0864ce4-0126-408e-ad0b-5302cffe1ff3
…ooping Override Process_vkCmdWriteTimestamp in VulkanReplayFrameLoopConsumer to skip writing timestamps on loop repetitions. This avoids "query not reset" validation errors when replaying traces that do not reset queries within the looped frame. TAG=agy CONV=a0864ce4-0126-408e-ad0b-5302cffe1ff3
Apply official clang-format guidelines to all hand-written files modified in our frame-looping fixes: - api_decoder.h - preload_file_processor.cpp - vulkan_decoder_base.h - vulkan_replay_frame_loop_consumer.cpp - vulkan_replay_frame_loop_consumer.h TAG=agy CONV=a0864ce4-0126-408e-ad0b-5302cffe1ff3
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emrekultursay
approved these changes
Jun 24, 2026
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Various fixes to support more games