On Fri, Jul 28, 2017 at 11:10:29AM +0200, Richard Braun wrote: > On Fri, Jul 28, 2017 at 09:58:54AM +0100, James Cowgill wrote: > > On 28/07/17 09:05, Richard Braun wrote: > > > On Thu, Jul 27, 2017 at 11:39:21PM +0100, James Cowgill wrote: > > >> While debugging a timing problem with FFmpeg on Hurd, I noticed that the > > >> "clock" function has a far lower precision on Hurd than it does on > > >> Linux, even though CLOCKS_PER_SEC is 1000000 on both. Why is this? > > >> > > >> I also found this patch to libc which may be responsible: > > >> hurd-i386/unsubmitted-clock_t_centiseconds.diff > > >> > > >> I'm not entirely sure why patching libc is appropriate to fix the > > >> claimed issues. > > > > > > The patch has nothing to do with precision. The kernel simply doesn't > > > have any high resolution timing system, whereas Linux does. > > > > In that case, clock should be returning multiples of whatever precision > > is supported by the kernel so that CLOCKS_PER_SEC is still correct. > > That macro is required by XSI to have this value, as described by POSIX [1].
I replied too quickly. I don't have all the details in mind but you may be right. Please use the bug-h...@gnu.org mailing list to report this issue upstream. -- Richard Braun
