ollama/x/create/quantpolicy.go
Patrick Devine 964ea42c09
mlx: x/create rewrite (#16919)
This is a rewrite of the create functionality for the MLX engine.

The core idea behind the create functionality is to break the import/convert into a pipeline of distinct phases:

* Read (scan the safetensors directory for the various bits of metadata)
* Classify (determine what the import type)
* Plan (determine any transforms that need to be done)
* Write (transform any data as necessary and write out the blobs)
* Create the manifest

Each architecture has a "policy" which determines how to convert the model correctly. A number of different formats for safetensors are supported including:

* nvfp4 (two formats: model optimized, torch)
* fp8 datatypes (convert to mxfp8)
* standard bf16 based weights

A number of cleanups/simplifications have been done including:

* using the baked in names for the tensors instead of munging them into something else
* unified 3d expert tensors (instead of separate per expert tensors)
* fewer unnecessary transforms to the various tensors in a model (keep a model as close to the source as possible)
* unified capability checking
* draft model handling (for MTP) is done on the same path

Image generation has been intentionally removed.
2026-07-03 18:30:45 -07:00

96 lines
3.1 KiB
Go

package create
import (
"regexp"
"strconv"
"strings"
)
// defaultQuantPolicy is the quantize policy for any architecture without a
// registered override: the shared GetTensorQuantization decision with no
// architecture-specific adjustments.
type defaultQuantPolicy struct{}
func (defaultQuantPolicy) quantizationType(name string, shape []int32, quantize string) string {
return GetTensorQuantization(name, shape, quantize)
}
// layerIndexRe extracts the layer index from tensor names like
// "model.language_model.layers.5.self_attn.v_proj.weight" or
// "model.language_model.layers.5.moe.experts.42.down_proj.weight"
var layerIndexRe = regexp.MustCompile(`\.layers\.(\d+)\.`)
// layerIndex returns the transformer layer index encoded in name, or -1.
func layerIndex(name string) int {
m := layerIndexRe.FindStringSubmatch(name)
if m == nil {
return -1
}
idx, err := strconv.Atoi(m[1])
if err != nil {
return -1
}
return idx
}
// useMoreBits returns true for layers where quantization-sensitive tensors
// should use higher precision: the first and last 1/8 of layers (which handle
// input grounding and final output refinement), plus every 3rd layer in between
// to limit error accumulation through the residual stream.
func useMoreBits(layerIdx, numLayers int) bool {
return layerIdx < numLayers/8 ||
layerIdx >= 7*numLayers/8 ||
(layerIdx-numLayers/8)%3 == 2
}
// eightBit returns the 8-bit quantization type in base's family: int8 for the
// affine family, mxfp8 for the fp4 family.
func eightBit(base string) string {
if base == "int4" || base == "int8" {
return "int8"
}
return "mxfp8"
}
// promoteEmbedding returns the 8-bit type in base's family when the embedding
// shape fits it, or "" when it does not. Token embeddings often double as the
// lm_head projection, where an 8-bit type keeps quality close to bf16 while
// saving decode bandwidth; the caller decides the fallback when 8-bit does not
// fit (the base type, or source precision).
func promoteEmbedding(shape []int32, base string) string {
if e := eightBit(base); isAligned(shape, e) {
return e
}
return ""
}
// sensitiveType resolves a quantization-sensitive projection (v/k/down): the
// 8-bit type in base's family when promote is set and fits the shape,
// otherwise the base type when it fits, otherwise source precision.
func sensitiveType(promote bool, shape []int32, base string) string {
if promote {
if e := eightBit(base); isAligned(shape, e) {
return e
}
}
if isAligned(shape, base) {
return base
}
return ""
}
// isEmbedTokensWeight returns true for the main token embedding weight.
func isEmbedTokensWeight(name string) bool {
return strings.HasSuffix(name, "embed_tokens.weight") &&
!strings.Contains(name, "per_layer")
}
// isVisionTower reports tensors under a model's vision tower.
func isVisionTower(name string) bool {
return strings.Contains(name, "vision_tower") || strings.Contains(name, ".visual.")
}
// isAudioTower reports tensors under a model's audio tower or audio embedding.
func isAudioTower(name string) bool {
return strings.Contains(name, "audio_tower") || strings.Contains(name, "embed_audio")
}