Re: [RFC] New Time of day proposal (updated 9/2/04)

Dominik Brodowski
2004-09-03T10:08:48Z

Hi John,

Thanks for this exciting code. A few questions:

- Where do you intend to put the "delay" code to? Generalize it as well?

- cpufreq hooks to tsc.c and i386_tsc.c[*] can easily be added. For them to
work _better_ than current code: can timeofday_hook() be called (with IRQs
disabled) _anywhen_ from kernel context?
[*] actually, only one of them needs the notifier, AFAICS...

- what about keeping lower-priority timesources still "active" in some sort to
a) enable loading _and_ unloading timsources (even modularizing them
becoms possible which should make testing easier...),
b) call them every couple of seconds to verify the currently used
timesource is still sane (and if not, call cpufreq_delayed_get() for
example or disable the timesource). This would mean that e.g. pmtmr
and pit can be used to "verify" and "backup" tsc, or otherwise...
The "clock=tsc" override would only affect the priority of the
timesource then, making it so large that no other timesource can
"preempt" it, but doesn't avoid making other timesources available
for backup and verification purposes.

Thanks,

Dominik