virtualbox.org

Hi, all,

I'm running Ubuntu 3.8.0-35 under VBox 4.3.6 on a Windows 7 host. All are 64 bit.

This is on a laptop with 6Gb RAM and an Intel i3-2328M processor (2 core. 4 thread, 2.2Ghz). I've allocated 1GB RAM to the virtual box and tried with both 1 and 2 processors allocated. Even with execution cap set at 100%, I get less than 30% of the total CPU allocated to the Virtual Box. Ubuntu's top command indicates a consistent usage > 100%, yet Windows Resource Monitor shows maybe 25% total usage.

The result is compiling a new Ubuntu kernel always takes 18+ hours, and depending on the options, has taken > 30 hours. Not real good when it should be done in 3-5 hours or so. Does anyone have any ideas?

TIA.

I'm not an Ubuntu expert, but if you want to recompile the kernel, it seems that you ought to have more than 1GB of RAM assigned to your guest. Perhaps it is way underpowered and forced to swap a lot. A visit to the guest system monitor should verify if you are indeed low on (guest) memory. From the description of your system, I would allocate 2GB to the guest.

As far as the CPU goes, your system is behaving properly. You assigned 1 out of 4 and if that is maxed out, then that's 25% of your total. I would not assign it more than 2. You may lock your host.

@socratis,

Thanks for the suggestion, but no, there is little swapping going on. Memory usage is relatively low and swap usage is not that high.

The kernel compile is just an example. Even when I just have a small cpu-intensive program running (i.e. just looping, doing nothing), CPU usage under the VM doesn't exceed about 28%.

I'll try increasing (again) to 2G, but when I did it before it made no difference. I dropped it down because I'm running multiple VM's concurrently for testing purposes.

Additionally, if there were a lot of swapping going on, Ubuntu's top wouldn't consistently show > 95% CPU usage.

Jerry

I raised the memory to 2GB, but no change. Even when the guest is running something very CPU intensive, host never goes over about 27-28% CPU utilization.

This causes a lot of problems for me. I'm developing code for a dedicated system, and am trying to use VB to speed up compiles (the dedicated system runs a single core processor at 1Ghz). I want to do the compiling and initial testing under VB for performance reasons. But right now, the dedicated system outperforms my laptop by > 2:1. Not what I was looking for .

socratis wrote:You assigned 1 out of 4 and if that is maxed out, then that's 25% of your total.

As I said, if you want to be brave and test out things, assign the max allowed number of CPUs to your guest. If the process that is running on the guest is multi-threaded, then you will see your host load rise. If it crashes your host and burns your hard drive to oblivion, don't blame me

@socratis, this is only a two core (4 thread) CPU. I have tried it with two cores, with no significant gain (it does give me a warning when I try to go above 2 CPUs, saying I'm exceeding the number of CPUs in the machine).

That would be a good idea, but it doesn't work. Ubuntu shows nearly 100% cpu utilization; IOW it's taking pretty much everything it has available, yet the host is still showing well under 30% utilization for the entire system. Even running multiple programs concurrently in different windows doesn't do it.

I was over and over this before posting here. It looks like the Execution Cap is just not working properly.