svn commit: r184108 - head/sys/i386/i386

Jung-uk Kim jkim at FreeBSD.org
Wed Oct 22 18:30:01 UTC 2008


On Wednesday 22 October 2008 11:53 am, Attilio Rao wrote:
> 2008/10/21, Jung-uk Kim <jkim at freebsd.org>:
> > On Tuesday 21 October 2008 06:07 am, Attilio Rao wrote:
> > > Something we could do with this is adding a "quirk" table of
> > > TSC arch dependant known to be working (based on cpu_model and
> > > such) and use that table in order to replace tsc_smp.
> >
> > Please note the invariant_tsc and smp_tsc are different.  If we
> > go with the route, we need two quirk tables. :-(
>
> It doesn't matter.
> I think it is silly we have different quirks flag states for TSC.
> We should just having a table assuming that the TSC is safe to use
> in SMP environments and gets rid of any other flag (in this case,
> for amd64 based machine, the logic could, for example, check if the
> CPU is P state invariant and assume it is safe, etc.)

Yes, it does matter as TSC is not just for timecounter and it can be 
used independently.  For example, if a thread is bound to a CPU, it 
can provide the fastest AND safest timer.
Besides, the whole point was not to modify TSC freq. if it is 
independent from CPU freq.

Jung-uk Kim


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