Investigated the DX12 present-thread overhead (~0.38 ms vs DX11 ~0.05 / GL ~0.09).
Per-stage timing of the D3D11On12 path showed the cost is NOT where you'd assume:
fence 0.005 + wrap(CreateWrappedResource+Acquire) 0.012 + copy 0.133 + flush 0.057 ms
CreateWrappedResource is cheap. The cost is the CopyResource issued on the 11On12
immediate context plus the mandatory Flush to make the shared copy visible to the
host -- both inherent to the bridge and not paid by the native-D3D11 path. The
per-frame GetDevice can't be skipped either (it's how device recreation is
detected). Documented this in the capture path.
Improving it means a native-D3D12 copy-queue path into a D3D12-shared texture, but
the host consumes the shared surface via IDXGIKeyedMutex (a D3D11 concept), so that
also requires switching the DX12 producer<->host sync to a shared ID3D12Fence -- a
cross-API rewrite. Deferred: the overhead is ~5% of a 144 Hz frame and correct.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
BlackMark
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