server: speed up single gguf creates (#5898)

server/model.go

@@ -176,9 +176,20 @@ func parseFromFile(ctx context.Context, file *os.File, digest string, fn func(ap
 			mediatype = "application/vnd.ollama.image.projector"
 		}
 
-		layer, err := NewLayer(io.NewSectionReader(file, offset, n), mediatype)
-		if err != nil {
-			return nil, err
+		var layer *Layer
+		if digest != "" && n == stat.Size() && offset == 0 {
+			layer, err = NewLayerFromLayer(digest, mediatype, file.Name())
+			if err != nil {
+				slog.Debug("could not create new layer from layer", "error", err)
+			}
+		}
+
+		// Fallback to creating layer from file copy (either NewLayerFromLayer failed, or digest empty/n != stat.Size())
+		if layer == nil {
+			layer, err = NewLayer(io.NewSectionReader(file, offset, n), mediatype)
+			if err != nil {
+				return nil, err
+			}
 		}
 
 		layers = append(layers, &layerGGML{layer, ggml})

server/model_test.go

@@ -2,8 +2,10 @@ package server
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"testing"
@@ -11,6 +13,7 @@ import (
 	"github.com/google/go-cmp/cmp"
 
 	"github.com/ollama/ollama/api"
+	"github.com/ollama/ollama/llm"
 	"github.com/ollama/ollama/template"
 )
 
@@ -133,3 +136,82 @@ The temperature in San Francisco, CA is 70°F and in Toronto, Canada is 20°C.`,
 		})
 	}
 }
+
+func TestParseFromFileFromLayer(t *testing.T) {
+	tempModels := t.TempDir()
+
+	file, err := os.CreateTemp(tempModels, "")
+	if err != nil {
+		t.Fatalf("failed to open file: %v", err)
+	}
+	defer file.Close()
+	if err := llm.WriteGGUF(file, llm.KV{"general.architecture": "gemma"}, []llm.Tensor{}); err != nil {
+		t.Fatalf("failed to write gguf: %v", err)
+	}
+
+	if _, err := file.Seek(0, io.SeekStart); err != nil {
+		t.Fatalf("failed to seek to start: %v", err)
+	}
+
+	layers, err := parseFromFile(context.Background(), file, "", func(api.ProgressResponse) {})
+	if err != nil {
+		t.Fatalf("failed to parse from file: %v", err)
+	}
+
+	if len(layers) != 1 {
+		t.Fatalf("got %d != want 1", len(layers))
+	}
+
+	if _, err := file.Seek(0, io.SeekStart); err != nil {
+		t.Fatalf("failed to seek to start: %v", err)
+	}
+
+	layers2, err := parseFromFile(context.Background(), file, layers[0].Digest, func(api.ProgressResponse) {})
+	if err != nil {
+		t.Fatalf("failed to parse from file: %v", err)
+	}
+	if len(layers2) != 1 {
+		t.Fatalf("got %d != want 1", len(layers2))
+	}
+
+	if layers[0].Digest != layers2[0].Digest {
+		t.Fatalf("got %s != want %s", layers[0].Digest, layers2[0].Digest)
+	}
+
+	if layers[0].Size != layers2[0].Size {
+		t.Fatalf("got %d != want %d", layers[0].Size, layers2[0].Size)
+	}
+
+	if layers[0].MediaType != layers2[0].MediaType {
+		t.Fatalf("got %v != want %v", layers[0].MediaType, layers2[0].MediaType)
+	}
+}
+
+func TestParseLayerFromCopy(t *testing.T) {
+	tempModels := t.TempDir()
+
+	file2, err := os.CreateTemp(tempModels, "")
+	if err != nil {
+		t.Fatalf("failed to open file: %v", err)
+	}
+	defer file2.Close()
+
+	for range 5 {
+		if err := llm.WriteGGUF(file2, llm.KV{"general.architecture": "gemma"}, []llm.Tensor{}); err != nil {
+			t.Fatalf("failed to write gguf: %v", err)
+		}
+	}
+
+	if _, err := file2.Seek(0, io.SeekStart); err != nil {
+		t.Fatalf("failed to seek to start: %v", err)
+	}
+
+	layers, err := parseFromFile(context.Background(), file2, "", func(api.ProgressResponse) {})
+	if err != nil {
+		t.Fatalf("failed to parse from file: %v", err)
+	}
+
+	if len(layers) != 5 {
+		t.Fatalf("got %d != want 5", len(layers))
+	}
+}