mlx: int4 groupsize 64 (#14682)

Change affine 4bit integers to use groupsize 64

x/create/client/quantize.go

@@ -21,7 +21,7 @@ var quantizeParams = map[string]struct {
 	bits      int
 	mode      string
 }{
-	"int4":  {32, 4, "affine"},
+	"int4":  {64, 4, "affine"},
 	"nvfp4": {16, 4, "nvfp4"},
 	"int8":  {64, 8, "affine"},
 	"mxfp8": {32, 8, "mxfp8"},

x/create/create.go

@@ -334,12 +334,12 @@ func GetTensorQuantization(name string, shape []int32, quantize string) string {
 	quantNorm := normalizeQuantType(quantize)
 
 	// MLX quantization requires last dimension to be divisible by group size
-	// nvfp4: 16, int4/mxfp8: 32, int8: 64
+	// nvfp4: 16, mxfp8: 32, int4/int8: 64
 	groupSize := int32(32)
 	switch quantNorm {
 	case "nvfp4":
 		groupSize = 16
-	case "int8":
+	case "int4", "int8":
 		groupSize = 64
 	}
 	if shape[len(shape)-1]%groupSize != 0 {