I thought we need 12 devices?

These are for the builders on the buildbot waterfall. The bots powering the buildbot builders are going to be swarming bots. This is the equivalent of https://build.chromium.org/p/chromium.perf/buildslaves/slave69-c1

What do you mean by 12 devices?

Oh nvm. I thought each of GCE is a swarming host, hence for 12 devices per builder, we would need 12 hosts.

I used slave208-c1 for Android Nexus5X Perf.

These have all been used.