Virtualbox only utilizing 25% of host CPU resources

[smsimeon]

Right, I got advised to post here with my issue in case anyone else has had it or can offer any advice.

My issue is really simple. My guest VM's can not utilize more than 25% of the CPU resources of the Host no matter what configuration I try.

I'm using an HP ProLiant DL380 G5, with two Intel Xeon x5450 @ 3GHz (4 cores each, no hyperthreading), 64 GB DDR2 memory @ 800Mhz and a ramdisk to run the VM's from in order to alleviate I/O performance issues I had with the guests prior.

I've uploaded my log from cold booting the VM, running normal GitLab operations (which is the purpose of that specific guest VM) and the powering it off.

There's also a screenshot from what I'm seeing attached as well.

[Martin]

Your host has 8 physical cores. In order to run a guest with 8 vCPUs every other task on the host needs to pause, even VirtualBox handling the guest.
So you will never have a decent performance with such a configuration.
Could you please test with just 6 vCPUs in the guest? This way your host has a free core to run VirtualBox and to handle all other necessary tasks outside the guest.

[smsimeon]

A little bit of a late reply, but better late than never.

I found out some really perplexing things. I tried previously the configuration that Martin suggested. My machine ran slower.
I then decided to go to the extreme. I gave the VM 16 vCPU's (which I don't actually have) and voila! My usage went up to 80-90% and after disabling nested paging, it went as high as it can get.
Now, I tried that same VM on a different machine (AMD FX-8350, 32GB DDR3 @ 1600Mhz) and that ran just fine with the configuration that was giving me trouble on my server.

Even with all this, the conclusion I came to was that I'll be getting a new workstation and delegating the current one to be my new server. Non-SLAT / NPT CPU's are apparently really old at this point.

[socratis]

I gave the VM 16 vCPU's (which I don't actually have) and voila! My usage went up to 80-90% and after disabling nested paging, it went as high as it can get.

And just to add a little bit to this, because the discussion was taking place over the IRC... Even key-developers of VirtualBox were surprised by such a behavior. I'm talking really surprised!