Enabling Flash Attention and Quantization in LM Studio for a performance boost | Alpha | PandaiTech

Enabling Flash Attention and Quantization in LM Studio for a performance boost

How to activate Flash Attention and KV Cache Quantization to reduce VRAM usage and speed up models when using large context windows.

Learning Timeline
Key Insights

The Benefits of Flash Attention

Flash Attention works like a 'smart lazy kid.' Instead of storing the entire token comparison table (matrix) in memory, it processes tokens in 'chunks' using optimized GPU routines. This significantly increases speed and drastically reduces VRAM load.

Impact of Quantization on VRAM

The lower the quantization value you choose (e.g., 4-bit vs. 8-bit), the less VRAM space is used. This is extremely helpful if you want to use a large 'Context Window' (like 128k tokens) on a GPU with limited memory capacity.

Performance Tips While Recording

If you are screen recording or using other graphics-intensive applications, make sure quantization settings are enabled. This prevents the model from slowing down or 'stuttering' since both applications are sharing the same hardware resources.
Step by Step

How to Enable Flash Attention & KV Cache Quantization

  1. Open LM Studio and select the model you want to load.
  2. Look at the settings panel on the right side and find the 'Experimental Features' section.
  3. Locate the 'Flash Attention' option and click the toggle to turn it ON.
  4. Scroll to the hardware settings section to find the 'KV Cache Quantization' option.
  5. Enable both data compression options (K Cache and V Cache) by clicking the provided toggles.
  6. Change the quantization level for both caches to a lower value, for example, select '4' (quant 4) for maximum VRAM savings.
  7. Adjust the 'Context Window' slider to a higher value (e.g., 128,000 tokens) to process long inputs.
  8. Click the 'Load Model' button to start the model with the optimized performance configuration.
  9. Monitor the memory usage on your GPU monitor to ensure the VRAM doesn't max out.

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