When setting up virtual machines on the various host systems I've used, be they Hyper-V, VMware or KVM, I have always allocated RAM in amounts that match physical memory configurations - e.g. to add 1GB of RAM I would add 1024MB, for 6GB of RAM I would add 6 x 1024 = 6144MB.
I realised that I've never thought about why I do this, it was just The Way Things Were Done at a previous workplace that I never questioned.
So, my question is, aside from the fact that it means virtualised operating systems can neatly round the allocated RAM to the nearest GB, are there any disadvantages to allocating RAM in quantities that are not powers of two, or multiples thereof? e.g. would there be any downside to adding 500MB of RAM, 750MB of RAM, or 1001MB of RAM?
Alternately, are there any advantages that would make this the recommended way of doing things?
I've left the question open-ended as far as host OS as I'd be interested to see if there are different considerations for the different hosts.