time issues and ZFS

[Adam McDougall]

On 01/22/13 07:27, Julian Stecklina wrote:
> Thus spake Daniel Braniss <danny at cs.huji.ac.il>:
>
>> In the meantime here is some info:
>> Intel(R) Xeon(R) CPU E5645: running with no problems
>>    LAPIC(600) HPET(450) HPET1(440) HPET2(440) HPET3(440) i8254(100) RTC(0)
>>
>> Intel(R) Xeon(R) CPU X5550: this is the problematic, at least for the moment
>>    HPET(450) HPET1(440) HPET2(440) HPET3(440) LAPIC(400) i8254(100) RTC(0)
>
> Does anyone know why the LAPIC is given a lower priority than HPET in
> this case? If you have an LAPIC, it should always be prefered to HPET,
> unless something is seriously wrong with it...
>
> Julian
>
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This may help:

"Problem with LAPIC timer is that it stops working when CPU goes to C3 
or deeper idle state. These states are not enabled by default, so unless 
you enabled them explicitly, it is safe to use LAPIC. In any case 
present 9-STABLE system should prevent you from using unsafe C-state if 
LAPIC timer is used. From all other perspectives LAPIC is preferable, as 
it is faster and easier to operate then HPET. Latest CPUs fixed the 
LAPIC timer problem, so I don't think that switching to it will be 
pessimistic in foreseeable future.

-- 
Alexander Motin"