On Tuesday 21 June 2011 11:56 am, John Baldwin wrote: > On Tuesday, June 21, 2011 11:48:55 am Jung-uk Kim wrote: > > On Tuesday 21 June 2011 09:10 am, John Baldwin wrote: > > > On Monday, June 20, 2011 7:41:00 pm Jung-uk Kim wrote: > > > > My questions to you: > > > > > > > > a) Why do we care TSC timecounter when it is not invariant > > > > where we *know* it is unusable and set to negative quality? > > > > > > What if the user knows they will not enable CPU throttling so > > > for them the TSC is safe? In that case, TSC is a more > > > efficient timecounter and if the user constrains the system to > > > make the TSC safe we should let them use it. > > > > In that case, it must be a UP system, the quality is still 800, > > and TSC value won't be shifted. > > > > My question was specific to SMP cases. Sorry, I didn't make that > > clear. > > What if the user has an SMP system where the TSCs are in sync but > it's older so it doesn't set the TSC invariant bit set in cpuid. > Are we now forbidding that user from using the TSC?
We do not forbid it but we cannot increase the quality because we don't compensate drift. Jung-uk Kim _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
