Enhance: try SageAttention for the SeedVR2 templates #207

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opened 2026-11-01 23:56:57 +00:00 by cameron · 0 comments
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SageAttention could speed up Sharpen / Rescue (SeedVR2) without touching the Fibo templates.

  • Why it might help:
    • SeedVR2's DiT step at 16 MP is dominated by attention: ~36 s for 7B and ~23 s for 3B on the 3090.
    • SageAttention (INT8 QK) is typically ~2× faster per attention op, so that step could drop to ~20–25 s.
    • The VAE encode/decode (~21 s) and model load aren't affected.
    • Fibo at ~1 MP would gain less (maybe 10–25%).
  • Scope:
    • SeedVR2 has its own attention_mode input on SeedVR2LoadDiTModel (sageattn_2), separate from ComfyUI's global --use-sage-attention.
    • Fibo uses core nodes and would only change if that global flag were set.
  • Linux (3090):
    • PyPI sageattention 1.0.6 is Triton-based (no compile).
    • It exposes sageattn_varlen with a signature compatible with what the node pack calls.
    • Not yet run.
    • SageAttention 2 needs an nvcc build; the system nvcc is 12.0 and torch is cu128.
  • Windows (4090):
    • Prebuilt SageAttention 2 wheels exist (they also use the 4090's FP8 path).
    • Not installed there today.
  • Plan:
    • Install on one machine.
    • Run Sharpen with attention_mode = sageattn_2 vs sdpa on the same photos.
    • Compare DiT time and quality (Sage occasionally adds faint artifacts).
    • If it's worth it, set it in /media/nas/image_seedvr2_*_imageapi_API.json.
SageAttention could speed up Sharpen / Rescue (SeedVR2) without touching the Fibo templates. - **Why it might help:** - SeedVR2's DiT step at 16 MP is dominated by attention: ~36 s for 7B and ~23 s for 3B on the 3090. - SageAttention (INT8 QK) is typically ~2× faster per attention op, so that step could drop to ~20–25 s. - The VAE encode/decode (~21 s) and model load aren't affected. - Fibo at ~1 MP would gain less (maybe 10–25%). - **Scope:** - SeedVR2 has its own `attention_mode` input on `SeedVR2LoadDiTModel` (`sageattn_2`), separate from ComfyUI's global `--use-sage-attention`. - Fibo uses core nodes and would only change if that global flag were set. - **Linux (3090):** - PyPI `sageattention` 1.0.6 is Triton-based (no compile). - It exposes `sageattn_varlen` with a signature compatible with what the node pack calls. - Not yet run. - SageAttention 2 needs an nvcc build; the system nvcc is 12.0 and torch is cu128. - **Windows (4090):** - Prebuilt SageAttention 2 wheels exist (they also use the 4090's FP8 path). - Not installed there today. - **Plan:** - Install on one machine. - Run Sharpen with `attention_mode = sageattn_2` vs `sdpa` on the same photos. - Compare DiT time and quality (Sage occasionally adds faint artifacts). - If it's worth it, set it in `/media/nas/image_seedvr2_*_imageapi_API.json`.
cameron added the needs-triage label 2026-11-01 23:56:57 +00:00
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