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

H. Peter Anvin
2008-09-24T18:17:18Z

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