Daniel P. Berrangé <berra...@redhat.com> writes: > On Fri, Oct 18, 2024 at 10:46:55AM +0100, Peter Maydell wrote: >> On Fri, 18 Oct 2024 at 10:01, Daniel P. Berrangé <berra...@redhat.com> wrote: >> > >> > On Thu, Oct 17, 2024 at 01:29:35PM -0300, Fabiano Rosas wrote: >> > > Daniel P. Berrangé <berra...@redhat.com> writes: >> > > >> > > > On Thu, Oct 17, 2024 at 11:32:11AM -0300, Fabiano Rosas wrote: >> > > >> Recent changes to how we invoke the migration tests have >> > > >> (intentionally) caused them to not be part of the check-qtest target >> > > >> anymore. Add the check-migration-quick target so we don't lose >> > > >> migration code testing in this job. >> > > > >> > > > But 'check-migration-quick' is only the subset of migration tests, >> > > > 'check-migration' is all of the migration tests. So surely this is >> > > > a massive regressions in covage in CI pipelines. >> > > >> > > I'm not sure it is. There are tests there already for all the major >> > > parts of the code: precopy, postcopy, multifd, socket. Besides, we can >> > > tweak migration-quick to cover spots where we think we're losing >> > > coverage. >> > >> > Each of the tests in migration-test were added for a good reason, >> > generally to address testing gaps where we had functional regressions >> > in the past. I don't think its a good idea to stop running such tests >> > in CI as gating on new contributions. Any time we've had optional >> > tests in QEMU, we've seen repeated regressions in the area in question. >> > >> > > Since our CI offers nothing in terms of reproducibility or >> > > debuggability, I don't think it's productive to have an increasing >> > > amount of tests running in CI if that means we'll be dealing with >> > > timeouts and intermittent crashes constantly. >> > >> > Test reliability is a different thing. If a particular test is >> > flaky, it needs to either be fixed or disabled. Splitting into >> > a fast & slow grouping doesn't address reliability, just hides >> > the problem from view. >> >> A lot of the current reliability issue is timeouts -- sometimes >> our CI runners just run really slow (I have seen an example where >> between a normal and a slow run on the same commit both the >> compile and test times were 10x different...) So any test >> that is not a fast-to-complete is much much more likely to >> hit its timeout if the runner is running slowly. When I am >> doing CI testing for merges "migration test timed out again" >> is really really common. > > If its frequently timing out, then we've got the timeouts > wrong, or we have some genuine bugs in there to be fixed. > >> > > No disagreement here. But then I'm going to need advice on what to do >> > > when other maintainers ask us to stop writing migration tests because >> > > they take too long. I cannot send contributors away nor merge code >> > > without tests. >> > >> > In general, I think it is unreasonable for other maintainers to >> > tell us to stop adding test coverage for migration, and would >> > push back against such a request. >> >> We do not have infinite CI resources, unfortunately. Migration >> is competing with everything else for time on CI. You have to >> find a balance between "what do we run every time" and "what >> do we only run when specifically testing a migration pullreq". >> Similarly, there's a lot of iotests but we don't run all of them >> for every block backend for every CI job via "make check". > > The combos we don't run for iotests are a good source of > regressions too :-( > >> Long test times for tests run under "make check" are also bad >> for individual developers -- if I'm running "make check" to >> test a target/arm change I've made I don't really want that >> to then spend 15 minutes testing the migration code that >> I haven't touched and that is vanishingly unlikely to be >> affected by my patches. > > Migration-test *used* to take 15 minutes to run, but that was a > very long time ago. A run of it today is around 1m20. > > That said, if you are building multiple system emulators, we > run the same test multiple times, and with the number of > targets we have, that will be painful. > > That could be a good reason to split the migration-test into > two distinct programs. One program that runs for every target, > and one that is only run once, for some arbitrary "primary" > target ?
What do you mean by distinct programs? It's not the migration-test that decides on which targets it runs, it's meson.build. We register a test() for each target, same as with any other qtest. Maybe I misunderstood you... > Or could we make use of glib's g_test_thorough > for this - a primary target runs with "SPEED=through" and > all other targets with normal settings. That would give us > a way to optimize any of the qtests to reduce redundant > testing where appropriate. This still requires a new make target I think. Otherwise we'd run *all* thorough tests for a QEMU target and not only migration-test in thorough mode. > > > If we move alot of testing out into a migration unit test, > this also solves the redundancy problem. > > > With regards, > Daniel
