Quantization
Converting model weights and activations from high precision (float32) to lower precision (int8, int4) to save memory and speed up computation.
Think of it like
Storing a photo in lower resolution to take up less disk space.
Example
A model with 7 billion float32 weights uses 28GB of memory. Quantize to int8 (1 byte per weight) and it's 7GB.
How it actually works
Quantization trades accuracy for speed and memory. Most of the loss happens in the first few bits; going from float32 to float16 hurts less than float16 to int4. Post-training quantization is easy but less accurate; quantization-aware training is harder but better. Modern quantization methods (GPTQ, AWQ) are surprisingly good.
For product teams
Quantization multiplies your serving capacity. A 7B model that wouldn't fit on one GPU now fits.
For engineers
Start with int8 post-training quantization. If that's too lossy, try QAT or mixed-precision.
Related
- Key compression technique.
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