ml/backend/ggml: create a new file descriptor for tensor (#10133)

improves model loading times on network-based filesystems
such as GCS fuse by creating a dedicated file descriptor for each
section of the file being read, reducing seeking

ml/backend/ggml/ggml.go

@@ -319,7 +319,14 @@ func New(ctx context.Context, r *os.File, params ml.BackendParams) (ml.Backend,
 				tts[i] = tt
 			}
 
-			sr := io.NewSectionReader(r, int64(meta.Tensors().Offset+t.Offset), int64(t.Size()))
+			// Create a new FD for each goroutine so that each FD is read sequentially, rather than
+			// seeking around within an FD shared between all goroutines.
+			file, err := os.Open(r.Name())
+			if err != nil {
+				return err
+			}
+			defer file.Close()
+			sr := io.NewSectionReader(file, int64(meta.Tensors().Offset+t.Offset), int64(t.Size()))
 			bts := make([]byte, 128*format.KibiByte)
 
 			var s uint64