dual G4 time issues..

On Sat, 12 Aug 2000, Gabriel Paubert wrote:

On Sat, 12 Aug 2000, Paul Mackerras wrote:

quoted

Gabriel Paubert writes:

quoted

quoted

Certainly on my 7600 with a 2-cpu powersurge board, with the code that
is currently in the devel kernel to use the tb register, you don't get
the same time on both cpus.

Yes, we need a way to check that the timebase are in sync and to sync
them if they are not. That's basically the same problem in any case.
The problem is to do it in a way that works on all machines...

Until we get SMP working on the 2-cpu G4 machines (hopefully I will be
getting one soon), the old powersurge board is the only supported SMP
powermac.  I found with mine that when you start the second CPU, it
stops the decrementers (and I expect timebases as well) on both CPUs
until you send an interrupt from the primary to the secondary cpu.

Benh and I are pushing Mac G4 SMP patches into the recently
created linuxppc_2_5 tree. It currently seems to work reasonably well,
except there is some work needing to be done on syncing the timebases on
CPU's. I seem to have about a 14 second difference between the 2 CPU's on
the machine I'm testing on now.

(from ping -f)

43505 packets transmitted, 43504 packets received, 0% packet loss
round-trip min/avg/max = -144657.0/0.1/144657.3 ms


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