tests/snap: make balloon checks more reliable

When checking the functionality of the balloon device, we use an
application to fault in some memory inside the guest, then try to
reclaim some memory back using the balloon.

Make the balloon check function fault in and reclaim a more significant
amount of memory such that the test does not get affected by other
processes in the guest that are maybe using memory temporarily.

Signed-off-by: Alexandru-Cezar Sardan <[email protected]>

Author: Alexandru-Cezar Sardan

tests/integration_tests/functional/test_snapshot_restore_cross_kernel.py

@@ -35,14 +35,14 @@ def _test_balloon(microvm, ssh_connection):
 
     # Check memory usage.
     first_reading = get_stable_rss_mem_by_pid(firecracker_pid)
-    # Dirty 60MB of pages.
-    make_guest_dirty_memory(ssh_connection, amount=(60 * MB_TO_PAGES))
+    # Dirty 300MB of pages.
+    make_guest_dirty_memory(ssh_connection, amount=(300 * MB_TO_PAGES))
     # Check memory usage again.
     second_reading = get_stable_rss_mem_by_pid(firecracker_pid)
     assert second_reading > first_reading
 
-    # Inflate the balloon.
-    response = microvm.balloon.patch(amount_mib=40)
+    # Inflate the balloon. Get back 200MB.
+    response = microvm.balloon.patch(amount_mib=200)
     assert microvm.api_session.is_status_no_content(response.status_code)
 
     third_reading = get_stable_rss_mem_by_pid(firecracker_pid)