Ubuntu – Hyper-V Dynamic Memory for Ubuntu 15.10

hyper-vUbuntuubuntu-15.10windows 10

I'm running the latest Windows 10 Pro Fall Update, and setup a guest OS of Ubuntu Desktop 64-Bit 15.10 in Hyper-V. I'm trying to use the dynamic memory feature, but Hyper-V wants to assign far more memory (5-10x) than the guest OS appears to be using:

Hyper-V Assigned Memory and Guest OS Memory Usage

In Hyper-V Manager

Startup Memory: 1024 MB
Dynamic Memory: Enabled
Minimum Memory: 1024 MB
Maximum Memory: 8192 MB
Assigned Memory: 4232 MB
Memory Demand: 3597 MB

In Guest OS, Ubuntu System Monitor

691 MiB (16%) of 4.1 GiB
0 bytes of 4.0 GiB

This is with Ubuntu just at the desktop, running top or system monitor. Bothy top and system monitor show no memory hogs, Compiz is the biggest user at ~210 MiB, everything else is 50 MiB or smaller.

The memory settings in Hyper-V for the VM are:

RAM:     1024 MB (Not sure if this is used when dynamic memory is turned on)
Min RAM: 1024 MB
Max Ram: 8192 MB
Memory Buffer: 20%

Best Answer

System monitor is probably excluding the RAM used for caching. Use 'free -m' on the command line to see how much is really used with and without caching. It will likely be close to the 4GB assigned RAM.

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