[ntp:questions] Linux 11-minute mode (RTC update)

Serge Bets serge.bets at NOSPAM.laposte.invalid
Thu Jul 24 13:30:29 UTC 2008


 On Thursday, July 24, 2008 at 1:48:40 +0000, Bill Unruh wrote:

> Apparently the HPET disables the rtc interrupts and takes them over.

Those HPET emulated RTC interrupts indeed seem to be nothing else than
unusable rubbish, by design. They introduce an unacceptable level of
error in the measures. Error 4 orders of magnitude greater than what's
reasonably expectable from proper RTC interrupts.


> No amount of care in the hwclock program can get around this kind of
> nonesense.

Exactly. Disabling HPET seems the only solution to have proper RTC
interrupts. Alternatively tell hwclock to *not* use interrupts, via
either the --directisa or --nointerrupt options. This is less elegant,
and costs many processor cycles. But accuracy should be good.


Serge.
-- 
Serge point Bets arobase laposte point net




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