[time-nuts] FreeBSD, NetBSD, or Minix-III?

Lux, James P james.p.lux at jpl.nasa.gov
Sat May 16 21:04:12 UTC 2009




On 5/16/09 8:04 AM, "Chuck Harris" <cfharris at erols.com> wrote:

> Bob Paddock wrote:
>> On Sat, May 16, 2009 at 9:21 AM, Chuck Harris <cfharris at erols.com> wrote:
>
>> 
>>> Why do you think Minix-III would be a good candidate for a time server?
>> 
>> Minix-III is based on the microkernel approach of keeping things small and
>> fast.
>> Take a look at the web site.  http://www.minix3.org/
> 
> I spent an extensive amount of time writing system features for
> Minix, back in the day, and even though it was a microkernel,
> it was anything but fast.
> 
> The good thing about microkernels is they have a very small section
> of "trusted" code in the kernel.  Everything else is in user space.
> This has nothing to do with speed; it has to do with where the work
> gets done.  Ultimately the work has to be done, and that is what causes
> bloat and slow operation.  In microkernel systems, the kernel operates
> as a task starter, arbiter, allocator of system resources and messaging
> system.  Everything is done by passing messages.  The problem with the
> microkernel system is your messaging system has to copy tons of data
> to do even trivial things.  Another problem is the kernel has to read
> the message, interpret what the message means, and check it for validity
> before it can do the bidding of the user level task.
> 
> In academia, everyone talks of microkernel systems as being the
> wave of the future, but in the real world, things end up more in
> the monolithic kernel model... linux and BSD are both monolithic
> kernels.


I think there is more use of microkernels (eCos, RTEMS, Erlang, etc.) in the
embedded world. The environment is more constrained, so reducing the
footprint is useful.

> 





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