I have a one-off task that requires me to use a VM to fix a build bug a software project using SCons (Python). The testing cycle is fairly short, resulting in frequent rebuilds. I'm using a 4-core laptop to host the VM and doing little else (a handful of tabs in Firefox, one terminal window for vim) aside from the work in the VM itself. I'm considering increasing the hardware allotment to the VM from 2 to 4 cores, but this would give all of my cores to the VM. Is this a terrible idea?

More info in case it matters:
VirtualBox on Ubuntu 18.04 LTS
RAM: 2GB of 8GB used according to free, 4GB allocated to the VM. Storage: 256GB SSD (M.2)


This should not be a problem - worst case it will make your desktop sluggish. The biggest gotcha with resource allocation is oversubscribing RAM and causing the parent to swap, followed by disk IO bottlenecks in general (which can be somewhat mitigated by using an SSD)

  • I am using an SSD. Updated original question with that information. So if I keep memory allocation well within available RAM, processors are not as important? Would it be safer to allocate 3 instead of 4 processors? – user3.1415927 Nov 25 '18 at 2:08
  • Processors are important, but you are unlikely to lick you system up by over subscribing the CPU. All of this us quite safe, and yes, allocating 3 CPUs may allow more responsiveness on the host, but it's not a big deal. – davidgo Nov 25 '18 at 2:10

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