Merge branch 'main' into 4534

Author: roypat

docs/ballooning.md

@@ -263,3 +263,20 @@ cannot be enabled later by providing a `polling_interval` non-zero value.
 Furthermore, if the balloon was configured with statistics pre-boot through a
 non-zero `stats_polling_interval_s` value, the statistics cannot be disabled
 through a `polling_interval` value of zero post-boot.
+
+## Balloon Caveats
+
+- Firecracker has no control over the speed of inflation or deflation; this is
+  dictated by the guest kernel driver.
+
+- The balloon will continually attempt to reach its target size, which can be a
+  CPU-intensive process. It is therefore recommended to set realistic targets
+  or, after a period of stagnation in the inflation, update the target size to
+  be close to the inflated size.
+
+- The `deflate_on_oom` flag is a mechanism to prevent the guest from crashing or
+  terminating processes; it is not meant to be used continually to free memory.
+  Doing this will be a CPU-intensive process, as the balloon driver is designed
+  to deflate and release memory slowly. This is also compounded if the balloon
+  has yet to reach its target size, as it will attempt to inflate while also
+  deflating.

tests/integration_tests/functional/test_kvm_ptp.py

@@ -6,19 +6,18 @@
 import pytest
 
 
-def test_kvm_ptp(uvm_plain_any):
+def test_kvm_ptp(uvm_any_booted):
     """Test kvm_ptp is usable"""
 
-    vm = uvm_plain_any
+    vm = uvm_any_booted
     if vm.guest_kernel_version[:2] < (6, 1):
         pytest.skip("Only supported in kernel 6.1 and after")
 
-    vm.spawn()
-    vm.basic_config(vcpu_count=2, mem_size_mib=256)
-    vm.add_net_iface()
-    vm.start()
+    _, dmesg, _ = vm.ssh.check_output("dmesg |grep -i ptp")
+    assert "PTP clock support registered" in dmesg
 
-    vm.ssh.check_output("[ -c /dev/ptp0 ]")
+    # wait up to 5s to see the PTP device
+    vm.ssh.check_output("udevadm wait -t 5 /dev/ptp0")
 
     # phc_ctl[14515.127]: clock time is 1697545854.728335694 or Tue Oct 17 12:30:54 2023
     vm.ssh.check_output("phc_ctl /dev/ptp0 -- get")