[NTLUG:Discuss] RH9 and VMWARE

[Iostream@comcast.net]

VMWare allows a system to run multiple operating systems at the same time... It
is similar to the larger systems (Mainframe, Large Unix boxen, etc) LPAR
partitioning.  On workstations, VMWare is often used by developers to run
multiple versions of a single OS on the same system, or to test
interoperability.  A few people use it to run windows and some windows
applications on top of Linux where this is needed, though Crossover Office seems
to do a good enough job there for most people.
The changes to the kernel in RH9 that would directly effect its running in
VMWare lie in the new threading (NPTL) and scheduler changes.  The downside to
VMWare, especially Workstation or GSX, is that the host OS is using a scheduler
to time share the processor between applications.  VMWare is considered an
application here.  VMWare also has a scheduler which should timeshare between
the applications.  This scheduler is the kernel of the guest OS unless you are
running ESX, but that is a whole different deal.  Anyway, the new scheduler in
RH9 doesnt expect that it is scheduling on top of a scheduler, so that can have
a serious effect on the way that the system performs.  What can happen in effect
is the guest OS scheduler and the host OS scheduler can work against each other
trying to optimally schedule themselves.  Hopefully VMWare can update itself to
work with this.  It would not be too hard to do as the scheduler code is visible
and they can see how it should react to specific workloads.

Justin

> >I saw a couple of instances of VMWare and RH9.
> >Just wanted to mention a perfromance warning...
> >
> >RH9 did something to the kernel ( someone
> >mentioned this ) that really, really trashes performance
> >of a linux RH9 guest. So... if you want to run a RH9 guest,
> >you need to pass the nosysinfo setting to the kernel at
> >boot time. With Grub just add nosysinfo to the startup
> >line for your kernel image.
> >
> >jack
> i would be interested to know a little more background on this.  What is 
> running a RH9 guest?  What does that mean?  What did RedHat do to the kernel 
> and what does the nosysinfo direct the kernel to do?
> 
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