[time-nuts] FreeBSD, NetBSD, or Minix-III?
Magnus Danielson
magnus at rubidium.dyndns.org
Mon May 18 08:03:24 UTC 2009
Hal Murray skrev:
>>> I'm interested in the case where interrupts and scheduling are
>>> enabled so there may be arbitrary gaps inserted into the simple
>>> code.
>
>> Interrupts enabled means that you can't make it reliable.
>
> Sure you can. Just compare the two high samples and try again if they are
> different.
>
> This disadvantage is that you get more jitter on how long it takes to get the
> answer. That may be better than taking the overhead of a system call to get
> into the kernel.
If we are talking about timestamping an interrupt for instance this
should not be a major issue. For a micro-kernel, things which normally
go into a device driver should be put in a suitable task.
Cheers,
Magnus
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