This issue is a follow-up on https://github.com/IntelPython/dpctl/pull/894 which have already added nice attributes to sycl devices and kernels. This attribute `sub_group_sizes` is listed in the [array of device attribute descriptors of the SYCL spec](https://registry.khronos.org/SYCL/specs/sycl-2020/html/sycl-2020.html#table.kernel.devicespecificinfo) but it's not an attribute of `SyclDevice` (while e.g `max_work_group_size` or `max_num_sub_groups`). In the meantime I wonder if `max_work_group_size // max_num_sub_groups` is supposed to be always equal to "`min(sub_group_sizes)`" ? Also I understand that `max_sub_group_size` can't be implemented because it needs actions in `libsycl`, is there a follow up issue on this ?