So, to be concrete:

You want to run telemetry_perf_tests on the "Mojo Linux Perf Builder" on the chromium.perf.fyi waterfall, and you want that builder to be a test-only builder triggered from the "Linux Builder" on chromium.perf ?

If so, I'm not sure that crossing builders like this is a good idea, as it confuses the "fyi-ness" of things. Do we want to do this because we don't have a "Linux Builder" on the perf.fyi waterfall right now?

Yes, that's what we want. Normally this would work fine, although technically it probably shouldn't. It's broken because Linux Perf isn't running any tests right now.

I also thought about adding a Linux Builder to the fyi waterfall. That would work as well. If that's what you think is the better solution, I'm fine doing that.

Here's a CL which is one way to implement this change: https://chromium-review.googlesource.com/c/565898/. I added a bit more to the description there.

Re: #1
>  Do we want to do this because we don't have a "Linux Builder" on the perf.fyi waterfall right now?

My understanding is that we want to get the Mojo Linux builder on FYI working so that Mojo team can use it to get performance data from their FYI config, not to replace data from the downed "Linux Builder". Stephen, Ned, is that correct?

I would rather add a Linux Builder to the FYI waterfall than cross masters between "sheriffed" and "fyi".

It's not an intrinsically bad idea to trigger optional tests off of a normal builder but I think we're just not conceptually set up for such a thing at the moment.

But I thought we'd been doing that for a long time already?

If we were, I didn't know about it and would rather not do that, but I could perhaps be convinced otherwise.

Generally speaking I'd expect every master to be independent and changes to one shouldn't affect others.

+dtu, isn't one of the main ideas behind build-per-revision that other masters (specifically tryserver.chromium.perf) can pick up builds from chromium.perf master? It seems kinda silly to have so much hardware for doing builds and then request more hardware for building on FYI. In general I think it will be pretty rare that FYI needs a build config that the main chromium.perf doesn't have.

Mojo Linux Perf Builder doesn't exist anymore. Closing.