convert: skip reading into memory when possible (#11507)

if there's no transformation to the tensor and the input and output
types match, copy directly into the writer. also read from a bufio with
a 32K buffer

convert/reader_safetensors.go

@@ -1,6 +1,7 @@
 package convert
 
 import (
+	"bufio"
 	"bytes"
 	"encoding/binary"
 	"encoding/json"
@@ -124,26 +125,41 @@ func (st safetensor) WriteTo(w io.Writer) (int64, error) {
 	}
 	defer f.Close()
 
-	if seeker, ok := f.(io.Seeker); ok {
+	r, err := func() (io.Reader, error) {
-		if _, err := seeker.Seek(st.offset, io.SeekStart); err != nil {
+		if readerAt, ok := f.(io.ReaderAt); ok {
-			return 0, err
+			return io.NewSectionReader(readerAt, st.offset, st.size), nil
-		}
+		} else if seeker, ok := f.(io.Seeker); ok {
-	} else {
+			_, err := seeker.Seek(st.offset, io.SeekStart)
-		if _, err := io.CopyN(io.Discard, f, st.offset); err != nil {
+			return f, err
-			return 0, err
+		} else {
+			_, err := io.CopyN(io.Discard, f, st.offset)
+			return f, err
 		}
+	}()
+	if err != nil {
+		return 0, err
+	}
+
+	br := bufio.NewReaderSize(r, min(32<<10, int(st.size)))
+	// special case when input and output are same type and the
+	// tensor doesn't need repacking
+	if (st.repacker == nil) &&
+		((st.dtype == "F32" && st.Kind() == tensorKindFP32) ||
+			(st.dtype == "F16" && st.Kind() == tensorKindFP16) ||
+			(st.dtype == "U8")) {
+		return io.CopyN(w, br, st.size)
 	}
 
 	var f32s []float32
 	switch st.dtype {
 	case "F32":
 		f32s = make([]float32, st.size/4)
-		if err = binary.Read(f, binary.LittleEndian, f32s); err != nil {
+		if err = binary.Read(br, binary.LittleEndian, f32s); err != nil {
 			return 0, err
 		}
 	case "F16":
 		u16s := make([]uint16, st.size/2)
-		if err = binary.Read(f, binary.LittleEndian, u16s); err != nil {
+		if err = binary.Read(br, binary.LittleEndian, u16s); err != nil {
 			return 0, err
 		}
 
@@ -154,14 +170,11 @@ func (st safetensor) WriteTo(w io.Writer) (int64, error) {
 
 	case "BF16":
 		u8s := make([]uint8, st.size)
-		if err = binary.Read(f, binary.LittleEndian, u8s); err != nil {
+		if err = binary.Read(br, binary.LittleEndian, u8s); err != nil {
 			return 0, err
 		}
 
 		f32s = bfloat16.DecodeFloat32(u8s)
-	case "U8":
-		// U8 tensors do not support repacking or type conversion.
-		return io.CopyN(w, f, st.size)
 	default:
 		return 0, fmt.Errorf("unknown data type: %s", st.dtype)
 	}

convert/reader_test.go

@@ -0,0 +1,232 @@
+package convert
+
+import (
+	"bytes"
+	"encoding/binary"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/d4l3k/go-bfloat16"
+	"github.com/google/go-cmp/cmp"
+	"github.com/x448/float16"
+)
+
+func TestSafetensors(t *testing.T) {
+	t.Parallel()
+
+	root, err := os.OpenRoot(t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer root.Close()
+
+	cases := []struct {
+		name,
+		dtype string
+		offset,
+		size int64
+		shape []uint64
+		setup func(*testing.T, *os.File)
+		want  []byte
+	}{
+		{
+			name:  "fp32-fp32",
+			dtype: "F32",
+			size:  32 * 4, // 32 floats, each 4 bytes
+			shape: []uint64{32},
+			setup: func(t *testing.T, f *os.File) {
+				f32s := make([]float32, 32)
+				for i := range f32s {
+					f32s[i] = float32(i)
+				}
+
+				if err := binary.Write(f, binary.LittleEndian, f32s); err != nil {
+					t.Fatal(err)
+				}
+			},
+			want: []byte{
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x3f, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x40, 0x40,
+				0x00, 0x00, 0x80, 0x40, 0x00, 0x00, 0xa0, 0x40, 0x00, 0x00, 0xc0, 0x40, 0x00, 0x00, 0xe0, 0x40,
+				0x00, 0x00, 0x00, 0x41, 0x00, 0x00, 0x10, 0x41, 0x00, 0x00, 0x20, 0x41, 0x00, 0x00, 0x30, 0x41,
+				0x00, 0x00, 0x40, 0x41, 0x00, 0x00, 0x50, 0x41, 0x00, 0x00, 0x60, 0x41, 0x00, 0x00, 0x70, 0x41,
+				0x00, 0x00, 0x80, 0x41, 0x00, 0x00, 0x88, 0x41, 0x00, 0x00, 0x90, 0x41, 0x00, 0x00, 0x98, 0x41,
+				0x00, 0x00, 0xa0, 0x41, 0x00, 0x00, 0xa8, 0x41, 0x00, 0x00, 0xb0, 0x41, 0x00, 0x00, 0xb8, 0x41,
+				0x00, 0x00, 0xc0, 0x41, 0x00, 0x00, 0xc8, 0x41, 0x00, 0x00, 0xd0, 0x41, 0x00, 0x00, 0xd8, 0x41,
+				0x00, 0x00, 0xe0, 0x41, 0x00, 0x00, 0xe8, 0x41, 0x00, 0x00, 0xf0, 0x41, 0x00, 0x00, 0xf8, 0x41,
+			},
+		},
+		{
+			name:  "fp32-fp16",
+			dtype: "F32",
+			size:  32 * 4, // 32 floats, each 4 bytes
+			shape: []uint64{16, 2},
+			setup: func(t *testing.T, f *os.File) {
+				f32s := make([]float32, 32)
+				for i := range f32s {
+					f32s[i] = float32(i)
+				}
+
+				if err := binary.Write(f, binary.LittleEndian, f32s); err != nil {
+					t.Fatal(err)
+				}
+			},
+			want: []byte{
+				0x00, 0x00, 0x00, 0x3c, 0x00, 0x40, 0x00, 0x42, 0x00, 0x44, 0x00, 0x45, 0x00, 0x46, 0x00, 0x47,
+				0x00, 0x48, 0x80, 0x48, 0x00, 0x49, 0x80, 0x49, 0x00, 0x4a, 0x80, 0x4a, 0x00, 0x4b, 0x80, 0x4b,
+				0x00, 0x4c, 0x40, 0x4c, 0x80, 0x4c, 0xc0, 0x4c, 0x00, 0x4d, 0x40, 0x4d, 0x80, 0x4d, 0xc0, 0x4d,
+				0x00, 0x4e, 0x40, 0x4e, 0x80, 0x4e, 0xc0, 0x4e, 0x00, 0x4f, 0x40, 0x4f, 0x80, 0x4f, 0xc0, 0x4f,
+			},
+		},
+		{
+			name:  "fp16-fp16",
+			dtype: "F16",
+			size:  32 * 2, // 32 floats, each 2 bytes
+			shape: []uint64{16, 2},
+			setup: func(t *testing.T, f *os.File) {
+				u16s := make([]uint16, 32)
+				for i := range u16s {
+					u16s[i] = float16.Fromfloat32(float32(i)).Bits()
+				}
+
+				if err := binary.Write(f, binary.LittleEndian, u16s); err != nil {
+					t.Fatal(err)
+				}
+			},
+			want: []byte{
+				0x00, 0x00, 0x00, 0x3c, 0x00, 0x40, 0x00, 0x42, 0x00, 0x44, 0x00, 0x45, 0x00, 0x46, 0x00, 0x47,
+				0x00, 0x48, 0x80, 0x48, 0x00, 0x49, 0x80, 0x49, 0x00, 0x4a, 0x80, 0x4a, 0x00, 0x4b, 0x80, 0x4b,
+				0x00, 0x4c, 0x40, 0x4c, 0x80, 0x4c, 0xc0, 0x4c, 0x00, 0x4d, 0x40, 0x4d, 0x80, 0x4d, 0xc0, 0x4d,
+				0x00, 0x4e, 0x40, 0x4e, 0x80, 0x4e, 0xc0, 0x4e, 0x00, 0x4f, 0x40, 0x4f, 0x80, 0x4f, 0xc0, 0x4f,
+			},
+		},
+		{
+			name:  "fp16-fp32",
+			dtype: "F16",
+			size:  32 * 2, // 32 floats, each 2 bytes
+			shape: []uint64{32},
+			setup: func(t *testing.T, f *os.File) {
+				u16s := make([]uint16, 32)
+				for i := range u16s {
+					u16s[i] = float16.Fromfloat32(float32(i)).Bits()
+				}
+
+				if err := binary.Write(f, binary.LittleEndian, u16s); err != nil {
+					t.Fatal(err)
+				}
+			},
+			want: []byte{
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x3f, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x40, 0x40,
+				0x00, 0x00, 0x80, 0x40, 0x00, 0x00, 0xa0, 0x40, 0x00, 0x00, 0xc0, 0x40, 0x00, 0x00, 0xe0, 0x40,
+				0x00, 0x00, 0x00, 0x41, 0x00, 0x00, 0x10, 0x41, 0x00, 0x00, 0x20, 0x41, 0x00, 0x00, 0x30, 0x41,
+				0x00, 0x00, 0x40, 0x41, 0x00, 0x00, 0x50, 0x41, 0x00, 0x00, 0x60, 0x41, 0x00, 0x00, 0x70, 0x41,
+				0x00, 0x00, 0x80, 0x41, 0x00, 0x00, 0x88, 0x41, 0x00, 0x00, 0x90, 0x41, 0x00, 0x00, 0x98, 0x41,
+				0x00, 0x00, 0xa0, 0x41, 0x00, 0x00, 0xa8, 0x41, 0x00, 0x00, 0xb0, 0x41, 0x00, 0x00, 0xb8, 0x41,
+				0x00, 0x00, 0xc0, 0x41, 0x00, 0x00, 0xc8, 0x41, 0x00, 0x00, 0xd0, 0x41, 0x00, 0x00, 0xd8, 0x41,
+				0x00, 0x00, 0xe0, 0x41, 0x00, 0x00, 0xe8, 0x41, 0x00, 0x00, 0xf0, 0x41, 0x00, 0x00, 0xf8, 0x41,
+			},
+		},
+		{
+			name:  "bf16-bf16",
+			dtype: "BF16",
+			size:  32 * 2, // 32 brain floats, each 2 bytes
+			shape: []uint64{16, 2},
+			setup: func(t *testing.T, f *os.File) {
+				f32s := make([]float32, 32)
+				for i := range f32s {
+					f32s[i] = float32(i)
+				}
+
+				if err := binary.Write(f, binary.LittleEndian, bfloat16.EncodeFloat32(f32s)); err != nil {
+					t.Fatal(err)
+				}
+			},
+			want: []byte{
+				0x00, 0x00, 0x80, 0x3f, 0x00, 0x40, 0x40, 0x40, 0x80, 0x40, 0xa0, 0x40, 0xc0, 0x40, 0xe0, 0x40,
+				0x00, 0x41, 0x10, 0x41, 0x20, 0x41, 0x30, 0x41, 0x40, 0x41, 0x50, 0x41, 0x60, 0x41, 0x70, 0x41,
+				0x80, 0x41, 0x88, 0x41, 0x90, 0x41, 0x98, 0x41, 0xa0, 0x41, 0xa8, 0x41, 0xb0, 0x41, 0xb8, 0x41,
+				0xc0, 0x41, 0xc8, 0x41, 0xd0, 0x41, 0xd8, 0x41, 0xe0, 0x41, 0xe8, 0x41, 0xf0, 0x41, 0xf8, 0x41,
+			},
+		},
+		{
+			name:  "bf16-fp32",
+			dtype: "BF16",
+			size:  32 * 2, // 32 brain floats, each 2 bytes
+			shape: []uint64{32},
+			setup: func(t *testing.T, f *os.File) {
+				f32s := make([]float32, 32)
+				for i := range f32s {
+					f32s[i] = float32(i)
+				}
+
+				if err := binary.Write(f, binary.LittleEndian, bfloat16.EncodeFloat32(f32s)); err != nil {
+					t.Fatal(err)
+				}
+			},
+			want: []byte{
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x3f, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x40, 0x40,
+				0x00, 0x00, 0x80, 0x40, 0x00, 0x00, 0xa0, 0x40, 0x00, 0x00, 0xc0, 0x40, 0x00, 0x00, 0xe0, 0x40,
+				0x00, 0x00, 0x00, 0x41, 0x00, 0x00, 0x10, 0x41, 0x00, 0x00, 0x20, 0x41, 0x00, 0x00, 0x30, 0x41,
+				0x00, 0x00, 0x40, 0x41, 0x00, 0x00, 0x50, 0x41, 0x00, 0x00, 0x60, 0x41, 0x00, 0x00, 0x70, 0x41,
+				0x00, 0x00, 0x80, 0x41, 0x00, 0x00, 0x88, 0x41, 0x00, 0x00, 0x90, 0x41, 0x00, 0x00, 0x98, 0x41,
+				0x00, 0x00, 0xa0, 0x41, 0x00, 0x00, 0xa8, 0x41, 0x00, 0x00, 0xb0, 0x41, 0x00, 0x00, 0xb8, 0x41,
+				0x00, 0x00, 0xc0, 0x41, 0x00, 0x00, 0xc8, 0x41, 0x00, 0x00, 0xd0, 0x41, 0x00, 0x00, 0xd8, 0x41,
+				0x00, 0x00, 0xe0, 0x41, 0x00, 0x00, 0xe8, 0x41, 0x00, 0x00, 0xf0, 0x41, 0x00, 0x00, 0xf8, 0x41,
+			},
+		},
+		{
+			name:  "u8-u8",
+			dtype: "U8",
+			size:  32, // 32 brain floats, each 1 bytes
+			shape: []uint64{32},
+			setup: func(t *testing.T, f *os.File) {
+				u8s := make([]uint8, 32)
+				for i := range u8s {
+					u8s[i] = uint8(i)
+				}
+
+				if err := binary.Write(f, binary.LittleEndian, u8s); err != nil {
+					t.Fatal(err)
+				}
+			},
+			want: []byte{
+				0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+				0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+			},
+		},
+	}
+
+	for _, tt := range cases {
+		t.Run(tt.name, func(t *testing.T) {
+			path := filepath.Base(t.Name())
+			st := safetensor{
+				fs:     root.FS(),
+				path:   path,
+				dtype:  tt.dtype,
+				offset: tt.offset,
+				size:   tt.size,
+				tensorBase: &tensorBase{
+					name:  tt.name,
+					shape: tt.shape,
+				},
+			}
+
+			f, err := root.Create(path)
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer f.Close()
+
+			tt.setup(t, f)
+
+			var b bytes.Buffer
+			if _, err := st.WriteTo(&b); err != nil {
+				t.Fatal(err)
+			}
+
+			if diff := cmp.Diff(tt.want, b.Bytes()); diff != "" {
+				t.Errorf("safetensor.WriteTo() mismatch (-want +got):\n%s", diff)
+			}
+		})
+	}
+}