3.0.0 b1 SMP issues

[jello3d]

I have Vbox 3.0.0 b 1 on Windwos Server 2008 x64. This is a Core i7 920, with hyperthreading enabled. 12GB ram.

As a test of SMP performance, I am doing 3d rendering using 3ds max on a Vista x64 client VM. The VM is in a .VHD created on Hyper-V on an identical system. Hyper-V is not install on the test host.

1) If I use 8 virtual CPUs in VBox (one for each thread), the VM does not boot. It will boot with 4.

2) A scene rendering in the physical OS renders in about 3:30... utilizing all 8 threads at 100%.
The same scene rendered on the same machine without hyperthreading renders in about 4:20.
The same scene rendered in the VM under Hyper-V, with or without hyperthreading on, also takes 4:20.
The same scene in the same VM, under VirtualBox with 4 virt Processors takes about 15:30.

So, interestingly, Hyper-V renders are near native processor speed, but the performance benefits of HyperThreading are lost.

VirtualBox 3 beta 1 clearly has some trouble utilizing the processor threads completely. Task manager shows that 4 of the 8 threads do get used, but they only get utilized to about 50% each... or a total CPU utilization of about 34%, when the VM's task manager believes it is using 100% of its 4 virtual processors.

We're getting there... but we're still very beta.

[Marian Kechlibar]

It seems that it has something to do with the installed HAL in the Windows guest. I have met similar challenges with mine (trying to compile huge projects with make -j 4).

Let us hope that beta 2 will resolve these issues.