[Ardour-Users] Ardour doesn't play
fatgerman at ntlworld.com
Sat Apr 12 09:19:12 PDT 2008
Where I work we are using Virtual Machines a great deal. Part of what we
do is real-time systems and we have not yet been able to get any of them
to run reliably in a VM. The issues are largely as described by the
others; because the hardware is emulated anything which relies on
regular scheduled access to resources or CPU cycles will not get the
kind of response it requires. It is possible to make them work but you
will never achieve anything close to the kind of real-time performance
you would get running them 'native'.
You might have success with Ardour/jack by increasing the buffer size
that jackd uses - QJackctl is the best solution to this as it allows you
to experiment much more easly, but I think you will find that the
latency you get will be unacceptable. Sound is one really big issue -
under VM you have jackd talking to alsa which talks to an emulated
device driver which then talks to the device driver within the host OS.
So to achieve low latency you need a low latency driver under your host
OS too, and the latency of that driver needs to be at least as low as
the latency of the jack/alsa setup. So even if you can get no xruns with
jack, the latency you end up with will be doubled because of the fact
the audio has to travel through the host's sound driver as well.
If you need two OS's, and you want to run low-latency audio under one of
them, then that one needs to be 'host' OS and you should run the other
OS under the VM. Dual-booting is always preferable, IMHO.
Justin M. Streiner wrote:
> On Sat, 12 Apr 2008, Brad Stafford wrote:
>> I run VMWare ESX 3.1 at work and VMServer at home. I know that VMWare
>> controls all hardware and emulates all hardware (CPU, memory, Disk)
>> presented back to the VM. VMWare recommends not running applications
>> like NTP (network time protocol) on a VM because it relies on CPU cycles
>> and VMWare server may decide to put that virtualized CPU to sleep at
>> any moment. VMWare provided an alternative to NTP with their VMTools in
>> order to sync time on VM's. I would venture to say you're going to have
>> a very difficult time getting RT anything successfully running in a VM.
> True. I would think that Ardour's resource needs, along with the resource
> needs of related components (jackd, plugins, etc) would make running
> Ardour in a VM a pretty dicey proposition.
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