PING: RFR: 8250598: Hyper-V is detected in spite of running on host OS

[Yasumasa Suenaga]

Hi Matthias, David,

I measured startup benchmarks with `Measure-Command {.\jdk\build\windows-x86_64-server-release\images\jdk\bin\java.exe --version}` on PowerShell.

* PC: Ryzen 3 3300X, 16GB memory
* OS: Windows 10 x64 (May 2020 Update)
* Java: jdk/jdk revision 60537
     (Compiled by VS 2019 (16.7.0))

* without patch
TotalMilliseconds : 70.2124
TotalMilliseconds : 64.4465
TotalMilliseconds : 59.0854
TotalMilliseconds : 68.0255
TotalMilliseconds : 72.6467
average : 66.8833

* with webrev.01
TotalMilliseconds : 81.7185
TotalMilliseconds : 68.539
TotalMilliseconds : 85.7226
TotalMilliseconds : 72.6584
TotalMilliseconds : 75.6091
average : 76.84952

Overhead of WMI seems to be +10ms in this case.


Yasumasa


On 2020/08/13 0:05, Baesken, Matthias wrote:
>> I understand that if the process runs on Xen on other hypervisor (e.g. KVM), information for Xen would be set between 0x40000100 and 0x40010000.
>> Ok, I will not remove the loop in new webrev, and will add comment about it.
> 
> Hi Yasumasa  , thanks !
> 
> Regarding the WMI overhead , if you could  get some more info on this it would be better to judge if it is perfectly okay or  concerning .
> 
> (I remember that I looked into it a couple of years ago , but decided not to use it in early VM startup ;  but have to confess this was just based on a "gut feeling",
>   No micro benchmarks  )
> 
> Best regards, Matthias
> 
>