Processor time allocation in VirtualBox

[Dmitrii]

Hi, I need to run several QNX 4.25 guest OS in VirtualBox. If I start 2 VMs or more Virtual Box allocate to each VM less prossesor time, than was set in config

Does anybody know how VirtualBox dinamically allocates processor time, by wich algoritm? It is very important cause I need to keep QNX as close to real time as possible.

[mpack]

You don't set processor time in the config. You can set a processor time cap in the config. By definition all VMs with a cap will be using less than the configured CPU cap. Allocation of CPU resources is mostly the responsibility of the host OS - and I note that you didn't ask your question in a specific host OS forum. You can generally assure optimal performance by allowing one core for each VM, plus one core for the host. E.g. on a 4-core host you could run 3 VMs.

[Dmitrii]

Yes, I understand that it is a cap, but if only one VM started and works in idle mode, it uses cpu time by the top of cap. So it consume 100% of cpu core performance? QNX in idle can't eat so much, but VB request this amount of cpu time. When it can't request cpu by the top of cap(2 or more VMs started), it request real amount what was needed.

Question is, how VB determines how much resources needed?
or, I don't understand something) anyway I need help

Tank you for advice. Unfortunately, I need to start at least 4-6 VMs on dual core processor with HT.