Offload
Offload is a method of moving model or parts of the model between the GPU memory (VRAM) and system memory (RAM) in order to reduce the memory footprint of the model and allow it to run on GPUs with lower VRAM.
Automatic offload
Tip
Automatic offload is set by the Settings -> Diffusers -> Model offload mode
Balanced
Balanced offload works differently than all other offloading methods as it performs offloading only when the VRAM usage exceeds the user-specified threshold.
- Recommended for compatible high VRAM GPUs
- Faster but requires compatible platform and sufficient VRAM
- Balanced offload moves parts of the model depending on the user-specified threshold
allowing to control how much VRAM is to be used - Default memory threshold is 75% of the available GPU memory
Configure threshold in Settings -> Diffusers -> Max GPU memory for balanced offload mode in GB
Warning
Not compatible with Optimum.Quanto qint quantization
Sequential
Works on layer-by-layer basis of each model component that is marked as offload-compatible
- Recommended for low VRAM GPUs
- Much slower but allows to run large models such as FLUX even on GPUs with 6GB VRAM
Warning
Not compatible with Quanto qint or BitsAndBytes nf4 quantization
Note
Use of --lowvram automatically triggers use of sequenential offload
Model
Works on model component level by offloading components that are marked as offload-compatible
For example, VAE, text-encoder, etc.
- Recommended for medium when balanced offload is not compatible
- Higher compatibility than either balanced and sequential, but lesser savings
Limitations: N/A
Note
Use of --medvram automatically triggers use of model offload
Manual Offload
In addition to above mentioned automatic offload method, SD.Next includes manual offload methods which are less granular and are only supported for specific models.
- Move base model to CPU when using refiner
- Move base model to CPU when using VAE
- Move refiner model to CPU when not in use
Performance Notes
- Tested using SDXL with 2 large LoRA models
- Sequential offload is default for GPUs with 4GB or less
- Balanced offload is default for GPUs with more than 4GB
Balanced offload is slower than no offload, but allows using large models such as SD35 and FLUX.1 out-of-the-box - Balanced offload set to default values
- LoRA overhead is measured in sec for first and subsequent iterations
- LoRA mode=backup can use up to 2x system memory
Using backup can be prohibitive on large models such as SD35 or FLUX.1
| Offload mode | LoRA type | LoRA mode | LoRA overhead | End-to-end it/s | Note |
|---|---|---|---|---|---|
| none | none | N/A | N/A | 6.7 | fastest inference |
| balanced | none | N/A | N/A | 4.5 | default without LoRA |
| sequential | none | N/A | N/A | 0.6 | lowvram |
| none | native | backup | 1.8 / 0.0 | 6.0 | |
| balanced | native | backup | 1.3 / 0.0 | 2.8 | |
| sequential | native | backup | 5.8 / 0.0 | 0.5 | |
| none | native | fuse | 1.3 / 1.3 | 4.8 | |
| balanced | native | fuse | 2.8 / 2.5 | 3.1 | default with LoRA |
| sequential | native | fuse | 8.8 / 7.7 | 0.4 | |
| none | diffusers | default | 2.9 / 2.9 | 3.8 | |
| balanced | diffusers | default | 2.2 / 2.2 | 2.1 | |
| sequential | diffusers | default | 4.6 / 4.6 | 0.3 | |
| none | diffusers | fuse | 5.7 / 5.7 | 2.0 | |
| balanced | diffusers | fuse | N/A | did not complete | |
| sequential | diffusers | fuse | N/A | did not complete |