Test Case 2
Testing Hotplug Memory Add
Last updated: 08/19/05

Since there is no hotplug memory remove yet, it will not be
possible to remove memory, then add it to test the add code. So,
to test the hot-add patches we will need to find a way to boot 
the machine  (or a virtual machine) without all the available 
memory and then exercise the hot-add patches by adding the memory. 
Since the hotplug system at OSDL is a power PC running a hypervisor,
this may be possible to do via virtualization, but investigation
is necessary to determine if it can be automated.

There's a boot option (mem=xxxM) that allows you to override the amount
of memory that the kernel detects for the machine at boot time. However
it seems that this option doesn't work well on systems with sparse mem.

Once memory is added, the first thing to do is to verify that 
the memory was actually added as seen from the user information. 
This should be easily seen in /proc/meminfo. 

To see if this memory is actually used after adding, there
were several suggestions made from instrumenting the kernel to running
benchmarks like AIM and making sure we exhaust all the memory.

We should also use statistics tools such as SAR to keep track of the
added memory. Then we could exhaust memory using a self-made tool that
allocates it to 100% utilized (verifying with sar), then add memory, 
then exhaust it again (verifying again that we move to 100% without swapping).

The tools (like sar) will have to be verified (testcase 6) before this
will work.