On Wed, Jul 08, 2020 at 04:15:11PM +0100, Stuart Henderson wrote: > On 2020/07/08 16:22, Richard Ipsum wrote: > > >Synopsis: userland gettimeofday not working? > > >Category: kernel > > >Environment: > > System : OpenBSD 6.7 > > Details : OpenBSD 6.7-current (GENERIC.MP) #336: Tue Jul 7 > > 22:27:36 MDT 2020 > > > > [email protected]:/usr/src/sys/arch/amd64/compile/GENERIC.MP > > > > Architecture: OpenBSD.amd64 > > Machine : amd64 > > >Description: > > gtod.c from > > https://undeadly.org/cgi?action=article;sid=20200708055508 > > still takes ~2 minutes after upgrading to latest snapshot. > > >How-To-Repeat: > > compile gtod.c and invoke as shown in blog post. > > user timecounters do not work everywhere, they require invariant TSC > ("ITSC" shown in cpu flags), plus they require that the TSCs are in > fairly close sync on the different cores, and that they don't drift > too much. > > On your machine there is too much difference between the TSC on > the cpu cores so can't be used as shown by this in your dmesg: > > > cpu1: TSC skew=-650 observed drift=0 > > cpu1: disabling user TSC (skew=-650) >
Ah I see, oh well, thanks for explaining. Richard
