"J. Roeleveld" <jo...@antarean.org> writes:

> On Thursday, April 23, 2015 11:02:24 PM lee wrote:
>> hydra <hydrapo...@gmail.com> writes:
>> >  You mean the documentation at Gentoo about Xen sucks or the upstream
>> > 
>> > documentation? What information are you missing from there? Maybe we can
>> > add  the missing pieces for Xen being more accessible and easier to use,
>> > what do you think? :)
>> 
>> I mean the documentation they have on their wiki.  It's a confusing mess
>> referring to various version with which things are being done
>> differently.
>
> The problem here is the different "implementations" that exist:
> - Xen (install and configure yourself, toolset: 'xl' , 'xm' is deprecated)
> - Citrix and XCP (pre-configured, install on dedicated server, toolset: 'xcp')
> - OVM (Oracle's implementation, not sure which toolset they use)

Maybe, maybe not; the documentation is so confusing that I can't really
tell what it is talking about.

>> Could you add missing pieces about why power management --- as in
>> frequency scaling --- doesn't work
>
> What doesn't work with this?
> The following seems quite detailed:
> http://wiki.xen.org/wiki/Xen_power_management

There was some command to query what frequencies the CPUs are running
on, and it didn't give any output.  Documentation seems to claim that
xen can do power management automagically, yet there was no way to
verify what it actually does.

> And the commands listed there (for the hypervisor based option) work on my 
> server.
>
>> and what to do about keeping the time
>> in sync between all VMs when you find out that this doesn't work as the
>> documentation would have you think it does?
>
> In what way doesn't it work?
> The clocks are all synchronized and I don't need to use anything like 'ntpd'

The clocks were off by quite a bit after a while, and I had to use ntp
to get them in sync.  Some documentation claims you don't need ntp or
anything; some other documentation apparently tries to explain that
keeping the clocks in sync cannot work unless the CPU(s) have some
features having to do with clock consistency while they are in sleep
states, and yet other documentation seems to say that using ntp cannot
work because xen screws it off.  In the end, it was recommended to me to
use ntp, which I found to work.  There was no way to figure out what xen
was actually doing or not doing towards this, and nobody seemed to know
how to keep the clocks in sync, other than using ntp, which appears to
be deprecated.


-- 
Again we must be afraid of speaking of daemons for fear that daemons
might swallow us.  Finally, this fear has become reasonable.

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