[ntp:questions] Flash 400 on all peers; can't get ntpd to be happy

Rob nomail at example.com
Sat Mar 12 16:48:57 UTC 2011


unruh <unruh at wormhole.physics.ubc.ca> wrote:
> On 2011-03-08, Ralph <ralph at depth.net> wrote:
>>
>>  
>>> When are you going to start working on it?
>>>  ... or are you asking others to do free programming
>>>   for you, to work around your unique problem?
>>  
>> Maybe I deserve that flame for having ranted a bit, but
>> I hardly think the problem of clock time that won't behave
>> within a linux guest VM is 'unique'.  Do a google search on
>> it, I'm clearly not the only one with this problem.
>
> Of course it is not unique. It is also unsolveable. A VM simply does not
> run in a way that it can keep accurate time. the only way to do it is to
> have the underlying OS that runs the VM keep accurate time and to have
> the VM gets its time from there. think about it-- there is no clock tha
> tthe VM can discipline to keep accurate time. Clocks based on CPU cannot
> work because the VM can be interrupted at will and stopped. Clocks based
> on hardware cannot work because you would run into the problem of 5
> different VM all fighting over the same hardware and constantly changing
> what the other had done. 

You have a fundamental misunderstanding of what a virtual machine system
is and how it operates.  It is the basic concept of a VM system that
it emulates hardware that a guest operating system can manipulate as if
it is real hardware, without having problems because of the same function
being performed by other guest systems running in other VMs.
So it is not at all true that "it cannot work".  It is how it is supposed
to work.  The fact that you don't have a picture of an implementation
in front of you does not mean it cannot work.

(and in fact, it works quite well in systems like VMware ESX)




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