Mailinglist Archive: opensuse (4626 mails)

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Re: [opensuse] Re: Timesync problem
  • From: John Andersen <jsa@xxxxxxxxxxxxxx>
  • Date: Mon, 15 Jan 2007 16:53:51 -0900
  • Message-id: <200701151653.57811.jsa@xxxxxxxxxxxxxx>
On Monday 15 January 2007 16:16, Joachim Schrod wrote:
> AFAIK, this happens if your host system is an SMP system (i.e., with
> multiple CPUs) and your guest system is configured as a
> single-processor CPU. The VMware instance seems to see only half of
> the jiffies on a 2-CPU system, or something like that.
>
> I don't know a way to resolve it short of configuring the VMware
> instance to use several CPUs as well.

Configuring guests with multiple CPUs probably won't help. It often
makes it worse to the point of being unusable.

To further pin this down, its only happens on multi-processor
smp systems where the individual processors to not keep
their timestamp counters (TSCs) in sync, such as some AMD machines
and Core 2 Duo processors.

You can prevent any problem by restricting a guest machine to a single cpu
rather than allowing it to bounce around from cpu to cpu.

You can do this like this

1 Make sure the virtual machine is powered off.
2 In a text editor, open the virtual machine's configuration file (.vmx file).
3 Add the following line for each processor with which you do not want to
associate the virtual machine (where <n> is the number of the processor on
the host):
processor<n>.use = FALSE

So for your first Virtual machine you might put in:
processor0.use = FALSE
and your second virtual machine you would put:
processor1.use = FALSE

That allows VMware to run using both processors, but the actual virtual
machine itself is using only one or the other.

You an also use taskset to restrict all of vmware to a single cpu.

http://kb.vmware.com/KanisaPlatform/Publishing/316/2039_f.SAL_Public.html



--
_____________________________________
John Andersen
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