This ties into some of the conversations we were having about upgrading the AMD GPU fleet. However I think we'll have to take some action in the interim to get things back to normal.

Ken, you were talking about splitting the ANGLE configs from the FYI configs. Turning off WebGL 2 / Windows / AMD from the ANGLE CQ would help this situation dramatically. That would require a different config for the ANGLE CQ. Would be happy to help with this.

Additionally we could consider removing the Win 7 AMD Debug bot:

https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win7%20FYI%20Debug%20(AMD)

I can't think of any reason why this bot is necessary. Seems redundant with our other Debug coverage. This would free up 1-2 of the 32 slaves.

Jamie, thanks for volunteering to help.

Looking more deeply at the bot configurations, in order to stop running WebGL 2.0 conformance on AMD on win_angle_rel_ng:

https://ci.chromium.org/p/chromium/builders/luci.chromium.try/win_angle_rel_ng

we actually don't need to split the configurations further, just rename one of them and stop running that test on "Win7 ANGLE Tryserver (AMD)". I'll do this.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/35d4c584c309cead14fbce8eda72c965f83d3025

commit 35d4c584c309cead14fbce8eda72c965f83d3025
Author: Kenneth Russell <kbr@chromium.org>
Date: Mon Jun 25 20:45:25 2018

Stop running WebGL 2.0 conformance on AMD on win_angle_rel_ng.

There aren't enough Windows AMD machines to run this test suite on AMD
GPUs against all ANGLE CLs. The suite runs on NVIDIA and Intel GPUs,
and the AMD-specific version doesn't catch many errors at this point,
so accept the potential for waterfall-only failures.

Bug:  854698 
Tbr: geofflang@chromium.org
Change-Id: Ifaacd8f559ab339bde24d345548fdf5257d6082e
Reviewed-on: https://chromium-review.googlesource.com/1112766
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#570166}
[modify] https://crrev.com/35d4c584c309cead14fbce8eda72c965f83d3025/testing/buildbot/chromium.gpu.fyi.json
[modify] https://crrev.com/35d4c584c309cead14fbce8eda72c965f83d3025/testing/buildbot/test_suites.pyl

I think the above CL will address the oversubscription. Please reopen if not. Thanks.