Re: [PATCH 1/2] VMware guest detection for x86 and x86-64

[H. Peter Anvin]

Cristi Magherusan wrote:
> On Wed, 2008-09-24 at 22:23 +0800, Yan Li wrote: 
> > On Wed, Sep 24, 2008 at 05:10:24PM +0300, Cristi Magherusan wrote:
> > > On Wed, 2008-09-24 at 20:22 +0800, Yan Li wrote:
> > > > Detects whether we are running as a VMware guest or not. Detection is
> > > > based upon DMI vendor string.
> > > >
> > > > It provides a function:
> > > > int is_vmware_guest(void)
> > > > that can be used easily to detect if we are running as a VMware guest
> > > > or not.
> > > We can also use this feature to force the HZ value to 100 or 250 at most
> > > when running in a virtual environment, since VirtualBox had some issues
> > > with this by taking a lot of CPU time when the HZ was set to 1000.
> > That's good. But this function is used for detecting VMware guest
> > only.  Do you think VMware also suffers from this problem?
> I don't know for sure about VMware, but someone who has it installed can
> try it. I had this issue with a CentOS 5-server virtual machine
> downloaded from http://www.thoughtpolice.co.uk/vmware/
>
> The fix consisted in using a kernel compiled with the HZ value set to
> 100 instead of the default which was 1000.

HZ is a compile-time constant, though.  Changing that would require 
adding a bunch of general divides, at the very least.

	-hpa
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