alloc-stress: add test to generate memory pressure from multiple processes

multichild-stress test spawns user-specified number of child processes
which allocate blocks of memory generating memory pressure on the device
and potentially causing lmk kills.
Typical usage: multichild-stress -i10 -s10000 -d100 -o500 -g
This generates 10 children each allocating 10000 bytes every 100ms,
oom_score of each child is 500 and each will have its own memory cgroup.
This test is mainly for testing lmkd performance.

Bug: 63631020

Change-Id: Ia1071ccc10924a7bae3735d3e5acde6fad195ca3
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
2 files changed