Add gradient checkpointing for DINOv3 and DGTRS-CLIP (bs 8→24)
- DINOv3: checkpoint each of 24 transformer blocks (recompute on backward) - DGTRS-CLIP: checkpoint each of 12 transformer blocks - Enables batch_size=24 on RTX 4090 (was 8 without checkpointing) - Peak VRAM: 20.3 GB at bs=24 (was OOM at bs=16 before) - ~20-30% slower per step, but 3x more in-batch negatives (23 vs 7) - Enabled by default (gradient_checkpointing=True in config) - Update README with VRAM benchmarks and checkpointing docs Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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31
README.md
31
README.md
@@ -186,10 +186,29 @@ Symmetric InfoNCE with learnable temperature (CLIP-style `logit_scale`):
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Loss and adapters run in **fp32** (AMP autocast disabled) to prevent gradient overflow.
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### Gradient checkpointing
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Gradient checkpointing trades compute for VRAM by recomputing activations during
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backward instead of storing them. Enabled by default (`gradient_checkpointing=True`).
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| Component | Without checkpointing | With checkpointing |
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|-----------|:---:|:---:|
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| DINOv3 (24 blocks) | stores all 24 block activations | recomputes on backward |
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| DGTRS-CLIP (12 blocks) | stores all 12 block activations | recomputes on backward |
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| **Max batch_size** (RTX 4090, shared encoder) | **8** | **24** |
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| Speed penalty | — | ~20-30% slower per step |
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VRAM tested on RTX 4090 (24 GB) with shared DINOv3 WEB + DGTRS-CLIP + text:
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| `batch_size` | Peak VRAM | Status |
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|:---:|:---:|:---:|
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| 16 | 14.7 GB | OK |
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| 24 | 20.3 GB | OK (recommended) |
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| 32 | >24 GB | OOM |
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### Gradient accumulation
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With `batch_size=8` on a 24 GB GPU, VRAM is the bottleneck. Gradient accumulation
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emulates a larger effective batch without extra memory:
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Gradient accumulation emulates a larger effective batch without extra memory:
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```
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effective_batch_size = batch_size × grad_accum_steps
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@@ -197,17 +216,17 @@ effective_batch_size = batch_size × grad_accum_steps
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| Setting | `batch_size` | `grad_accum_steps` | Effective batch | In-batch negatives |
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|---------|:---:|:---:|:---:|:---:|
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| Default | 8 | 1 | 8 | 7 |
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| Recommended | 8 | 8 | 64 | 7 per micro-batch |
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| Default | 24 | 1 | 24 | 23 |
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| Large effective batch | 24 | 4 | 96 | 23 per micro-batch |
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**Note:** gradient accumulation averages gradients across micro-batches, but each
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micro-batch still only sees `batch_size` in-batch negatives. To increase the number
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of negatives per forward pass, increase `batch_size` directly (requires more VRAM).
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```bash
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# Example: effective batch of 64 with 8 accumulation steps
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# Example: effective batch of 96 with gradient accumulation
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python -m src.training.train_gtauav --config conf/gtauav_balanced.gin \
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--filter-meta meta/seg_filter.json --grad-accum 8
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--filter-meta meta/seg_filter.json --batch-size 24 --grad-accum 4
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```
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### Metrics
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