Fix intermittent failures of test_balloon.py::test_size_reduction #4782
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## main #4782 +/- ##
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Coverage 84.34% 84.34%
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Tests that boot a microvm via a config file do not use `.start()`, as `.spawn()` already start the bootup process. This is probably why these tests were overlooked when we did the `.wait_for_up()` refactor. Fix potential issues by adding the `wait_for_up()` calls here, to replace various homegrown waiting solutions. Some tests do not have network devices, and also don't really need to wait for the guest to have booted as they only validate firecracker API responses. Don't try to use wait_for_up in those (since we can't anyway). Signed-off-by: Patrick Roy <[email protected]>
The assigned value was immediately overwritten without ever being read. Signed-off-by: Patrick Roy <[email protected]>
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Status: Awaiting review
Remove assignment to a variable that was never read Signed-off-by: Patrick Roy <[email protected]>
"Some times the ..." -> "Sometimes the ..." (no space) Signed-off-by: Patrick Roy <[email protected]>
This test serves no purpose, as all it does is take a snapshot without verifying anything about it. In this sense, it is perfectly subsumed by `test_balloon_snapshot`, which also creates snapshots with balloon devices, but actually verifies they restore as well (something that is not given in this test, because we do not wait for the guest to boot before taking a snapshot). A look at the commit history shows that this test used to be responsible for verifying cross-release snapshot support for the balloon device, but since we no longer support such a thing, it became superfluous. Signed-off-by: Patrick Roy <[email protected]>
Some of the tests in test_balloon.py were missing `microvm.wait_for_up()` calls. This was mainly visible from those that read the RSS of the firecracker process taking a long time to calibrate, due to RSS being very unstable during guest boot up. Signed-off-by: Patrick Roy <[email protected]>
Major page fault occur when a page fault can only be satisfied via disk I/O [1]. In `test_stats`, we asserted that the number of major page faults increased during execution of `make_guest_dirty_memory`, but this cannot happen, as it uses MAP_ANONYMOUS, and thus will not trigger any major page faults. The reason the test used to work in the past is that it was not waiting for the VM to boot, so the first reading of the balloon statistics happened before the boot process was finished. However, during boot we _do_ expect major faults to happen, as things need to be read from the rootfs. Fix the test to instead just assert a non-zero number of major faults happened during boot. [1]: https://en.wikipedia.org/wiki/Page_fault#Major Signed-off-by: Patrick Roy <[email protected]>
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Changes
Adds a bunch of missing
wait_for_ups, and clears up some excessive loggingReason
Missing
wait_for_upin various balloon tests caused RSS measurements to be taken during the boot process, which later results in intermittent failures. For example, intest_size_reduction, we try to inflate the balloon based on an RSS reading taken during boot, which leaves too little memory available for a booted guest.License Acceptance
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