Tweaking vm memory usage

When you run Linux on bare metal, it eventually uses all available memory for disk i/o cache, which makes sense in that case. However, if you run it in Qube, it would be reasonable to have the guest disk cache low, allowing the host system to handle it more appropriately and not eating everything up to “max memory”? Is there a guide to weak it for better performance?

Maybe you can disable memory balancing ( allocate a definite, small amount of memory to the VM), and change swappiness to 1.

I hope there’s an option in Xen to balloon a qube’s memory ONLY when necessary (for example, free space less than 10%). In other words, a qube mostly runs with its min mem.