Choose smarter defaults for --memory

[tstromberg]

While working with @priyawadhwa on a demo, I noticed that minikube was locking up. Increasing the memory size fixed the problem. Also, the first thing our documentation states after installation is to increase the memory size.

What if we were able to improve the first-start experience for most users by default, by dynamically selecting a more appropriate option for --memory?

My recommendation is to change the default 2GB setting to 37.5% of available memory by default: but never less than 2.25GB or more than 8GB. For instance:

• 4GB host -> 2.25GB VM
• 6GB host -> 2.25GB VM
• 8GB host -> 3GB VM
• 16GB host -> 6GB VM
• 32GB host -> 8GB VM
• 64GB host -> 8GB VM

The balance can be fine tuned, but my main argument is that a developer on a 16GB machine can probably live with a 6GB VM.

[afbjorklund]

This should leave some room for multi-node as well (eventually) ? Currently starting 4 VMs, which is 8G (when did the “2.25” happen?)

Some hypervisors can do “ballooning” and adjust memory on the fly (or more like give back what they stole from the real OS, but)
https://www.virtualbox.org/manual/ch04.html#guestadd-balloon

[Zyqsempai]

@tstromberg Do you have any idea how we can get the current available memory size?

[tstromberg]

@Zyqsempai - It's unclear if gopsutil, which we already have imported, gives us what we need. I worry that it may be conflating physical memory with swap:

https://github.com/shirou/gopsutil#usage

As an alternative, there is: https://github.com/pbnjay/memory

[afbjorklund]

I thought swap was in a separate Stat ? But haven’t actually verified

[priyawadhwa]

Related to #94

[afbjorklund]

Did we find out where the extra 0.25 came from ? i.e. why it requires even more memory now