ollama/x/create/draft.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

83 lines
3 KiB
Go

package create
import "fmt"
// CreateDraftLayers imports a draft (speculative-decoding / MTP assistant)
// safetensors model into prefixed tensor and config blobs and returns the
// layers WITHOUT writing a manifest — the caller folds them into the target
// model's manifest. A draft never stands alone; it always accompanies a target
// model named on the Modelfile's FROM line.
//
// It runs the same read → classify → plan → write pipeline as Create. Output
// tensor names keep their source form, namespaced by tensorPrefix (e.g.
// "draft.") so they cannot collide with the target's tensors; config blobs are
// named under configPrefix (e.g. "draft/").
func CreateDraftLayers(modelDir, tensorPrefix, configPrefix, quantize string, store BlobStore, fn func(status string)) ([]LayerInfo, error) {
if tensorPrefix == "" {
return nil, fmt.Errorf("draft tensor prefix must not be empty")
}
if configPrefix == "" {
return nil, fmt.Errorf("draft config prefix must not be empty")
}
defer sweepMLX()
inv, err := ReadInventory(modelDir)
if err != nil {
return nil, fmt.Errorf("read draft model: %w", err)
}
class, err := Classify(inv, quantize)
if err != nil {
return nil, err
}
policy, err := newTensorImportTransform(inv)
if err != nil {
return nil, fmt.Errorf("build draft quantization policy for %q: %w", inv.Config.Architecture(), err)
}
specs, err := Plan(inv, class, draftPolicy{policy})
if err != nil {
return nil, fmt.Errorf("plan draft model: %w", err)
}
specs = prefixSpecs(specs, tensorPrefix)
fn(fmt.Sprintf("importing draft (%d tensors%s)", len(inv.Tensors), quantizeStatus(class)))
layers, err := WriteBlobs(specs, modelDir, store)
if err != nil {
return nil, err
}
configLayers, _, err := importConfigBlobs(modelDir, configPrefix, store, fn)
if err != nil {
return nil, err
}
return append(layers, configLayers...), nil
}
// prefixSpecs returns specs with prefix prepended to every output blob name and
// output tensor name, leaving the source references (which point at the source
// files) untouched. Scale/bias keys derive from the tensor name, so they inherit
// the prefix automatically.
func prefixSpecs(specs []BlobSpec, prefix string) []BlobSpec {
out := make([]BlobSpec, len(specs))
for i, spec := range specs {
tensors := make([]TensorSpec, len(spec.Tensors))
for j, ts := range spec.Tensors {
ts.Name = prefix + ts.Name
tensors[j] = ts
}
out[i] = BlobSpec{Name: prefix + spec.Name, Tensors: tensors, Metadata: spec.Metadata}
}
return out
}
// draftPolicy wraps an architecture policy to keep a draft model's token
// embedding at source precision (drafts start with unquantized embeddings; this
// may change later). Every other tensor follows the wrapped policy. It is given
// unprefixed source names, since planning runs before prefixSpecs.
type draftPolicy struct{ inner quantizePolicy }
func (p draftPolicy) quantizationType(name string, shape []int32, requested string) string {
if isEmbedTokensWeight(name) {
return ""
}
return p.inner.quantizationType(name, shape, requested)
}