How guest could utilize 2 host cores (now only 1)?

vuser1 · Post by **vuser1** » 26. Jan 2009, 23:46

Hello!

My guest - Win2003-32bit - needs maximum muti-threading performance. And my goal is to give full CPU power to guest . The host is ububtu8.04. I read duscussion where some guy explained that there is no big reason to have SMP guest support because of VBox uses all the cores to run guest's threads.

I run 2 instances of CPUSTRES.EXE utility (part of WindowsNT ResourceKit) with 4 threads within each. So, there are 8 runnung threads on guest, but I see on the host that only 1 CPU core is loaded 100% and second one is almost idle.

I uses VBoxHeadless to run VM. TASKSET of VBoxHeadless returns CPU affinity mask 3 (0x11) - it means the process could run on 2 cores. Why it uses only 1? What option should I set to command VBox use both cores?

Post by **Martin** » 27. Jan 2009, 14:07

Currently you cannot use more than one CPU core for a single virtual machine. If you run multiple VMs they will we be distributed over all CPUs.

Martin

vuser1 · Post by **vuser1** » 28. Jan 2009, 09:02

Martin, thank you for reply. I apologize for stupid question. There is no possibility to use 2 cores withouht guest SMP support - from the host perspective, VM is just one thread, no matter how many threads are inside the guest.