> On 2 Jun 2017, at 16:48, Maxim Uvarov <maxim.uva...@linaro.org> wrote: > > On 06/02/17 12:44, Elo, Matias (Nokia - FI/Espoo) wrote: >>>> >>>> /** >>>> + * System huge page sizes in bytes >>>> + * >>>> + * Returns the number of huge page sizes supported by the system. Outputs >>>> up to >>>> + * 'num' sizes when the 'size' array pointer is not NULL. If return value >>>> is >>>> + * larger than 'num', there are more supported sizes than the function was >>>> + * allowed to output. If return value (N) is less than 'num', only sizes >>>> + * [0 ... N-1] have been written. Returned values are ordered from >>>> smallest to >>>> + * largest. >>>> + * >>>> + * @param[out] size Points to an array of huge page sizes for output >>>> + * @param num Maximum number of huge page sizes to output >>>> + * >>>> + * @return Number of supported huge page sizes >>>> + * @retval 0 on no huge pages >>>> + */ >>>> +unsigned odp_sys_huge_page_size_all(uint64_t size[], unsigned num); >>>> + >>> >>> I think it has to be int. -1 on error, 0 - no hp, > 0 pages. >>> For linux it might be similar to getpagesizes() >>> https://linux.die.net/man/3/getpagesizes >>> """ >>> if pagesizes is NULL and n_elem is 0, then the number of pages the >>> system supports is returned. Otherwise, pagesizes is filled with at most >>> n_elem page sizes. >>> """ >>> >> >> getpagesizes() returns -1 in a case of invalid function arguments. >> odp_sys_huge_page_size_all() is documented so that the application cannot >> pass invalid arguments. So an internal error would be the only possibility. >> I don't see this to be likely as the function is only reading system info. >> >> Adding -1 return value would also increase application complexity as the >> error return value would require special handling from application. >> > > We have to be consistent with all odp api functions. We do not have > unsigned function, they are int.
We do have odp_pktio_max_index(), which returns unsigned, and anyway this shouldn't be a reason not to use otherwise valid return value. Regarding consistency, not returning -1 follows the same return value style as the rest of the functions in system_info.h (odp_sys_huge_page_size(), odp_sys_page_size(), odp_sys_cache_line_size()). > This function is not fast path so > additional check is ok. And -1 can be returned on permission error to > assess /proc or /sys files for example or any other internal failure. >From application point of view the outcome is still the same (no huge pages) >and returning -1 would make this function inconsistent with the other >functions in this module as noted above. -Matias
