[libcxx-commits] [PATCH] D96267: [libcxx] Move Linaro AArch64 buildbots to buildkite

Louis Dionne via Phabricator via libcxx-commits libcxx-commits at lists.llvm.org
Wed Feb 17 12:22:34 PST 2021

ldionne added a comment.

In D96267#2568708 <https://reviews.llvm.org/D96267#2568708>, @DavidSpickett wrote:

> We split the build bots over a few big machines, so timing sensitive tests are often an issue. Thanks for the patch.
>> Also, what's your CI capacity like? From the build history, it looks like there's a single builder that takes roughly 1h30 to build. I expect that is going to be insufficient and that will stall the CI queue. Is there any way you could get an additional builder or a faster one? Otherwise, if you were able to check-in the Dockerfile you use into the libcxx repository, we could look into using the capacity we have on GCE to run those. Our GCE instances are huge and work like a charm.
> It's actually worse than that since I've only got one bot running at the moment, so the total is 3hr. I just wanted a baseline for how slow it is if we just treated it like the existing post commit bot. I'm sure I can bring that down a lot.

Got it. One thing we can do to reduce contention is put your jobs after the ` - wait` step in the BuildKite pipeline. That way, your jobs will only run if all the jobs above the `wait` succeeded. I use that to reduce the load on the macOS testers and it helps a lot.

> Do you happen to know how much extra capacity moving to pre-commit required for other bots? I assume there's maybe 2/3x more pre-commit runs than post commit.

To be honest, I don't know because the GCE instances that we use for all of our main jobs are so beefy they finish in a few minutes. In fact, they are scaled up/down automatically based on the number of jobs. To give you a general guideline based on what I've been seeing since the start of pre-commit CI, I think if you can have machines that run the tests in 30-45 minutes, just one or two of those should be sufficient since you only have two build jobs to dispatch. We can also add just one of the two jobs (say the one with exceptions enabled) with your current capacity and see how things go over the next few days/weeks. We'll adjust then.

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