To be more precise, some example failures:

WebglConformance_conformance2_glsl3_vector_dynamic_indexing
https://ci.chromium.org/buildbot/chromium.gpu.fyi/Win7%20FYI%20Release%20%28AMD%29/707

WebglConformance_conformance2_textures_canvas_sub_rectangle_tex_2d_rgb9_e5_rgb_half_float
WebglConformance_deqp_functional_gles3_textureshadow_2d_array_nearest_mipmap_linear_less
https://ci.chromium.org/buildbot/chromium.gpu.fyi/Win7%20FYI%20Release%20%28AMD%29/696

The WebglConformance_conformance2_textures_canvas_sub_rectangle_tex_2d_rgb9_e5_rgb_half_float failure in particular is strange:

https://chromium-swarm.appspot.com/task?id=3ca758334de03210&refresh=10&show_raw=1

[13/138] gpu_tests.webgl_conformance_integration_test.WebGLConformanceIntegrationTest.WebglConformance_conformance2_textures_canvas_sub_rectangle_tex_2d_rgb9_e5_rgb_half_float failed unexpectedly 5.7350s:
  
  Traceback (most recent call last):
    _RunGpuTest at content\test\gpu\gpu_tests\gpu_integration_test.py:132
      self.RunActualGpuTest(url, *args)
    RunActualGpuTest at content\test\gpu\gpu_tests\webgl_conformance_integration_test.py:204
      getattr(self, test_name)(test_path, *args[1:])
    _RunConformanceTest at content\test\gpu\gpu_tests\webgl_conformance_integration_test.py:218
      self._CheckTestCompletion()
    _CheckTestCompletion at content\test\gpu\gpu_tests\webgl_conformance_integration_test.py:214
      self.fail(self._WebGLTestMessages(self.tab))
    fail at .swarming_module\bin\Lib\unittest\case.py:410
      raise self.failureException(msg)
  AssertionError: should be 0,255,255
  at (16, 8) expected: 0,255,255 was 72,72,72
  FAIL should be 0,255,255
  at (16, 8) expected: 0,255,255 was 72,72,72
 

It's getting back gray for the readback results. The same 72,72,72 value is seen for some other readbacks in another test.

Haven't finished triaging all of these.

I'll report to AMD that we're seeing increased flakiness with their latest driver. (These machines' drivers were upgraded recently. The same sort of flakiness isn't seen on the NVIDIA bot.)

riajiang@: on second thought, as you're pixel wrangler could you please add flaky expectations for these few tests to this section of webgl2_conformance_expectations.py?

https://cs.chromium.org/chromium/src/content/test/gpu/gpu_tests/webgl2_conformance_expectations.py?l=265

kainino@ or I can review your patch. Thanks in advance for your help.

Thanks for tackling this. Also unsure as to the causes of this flakiness, if there are underlying Chromium causes or if these are all AMD specific flakes. The rgb9_e5_rgb_half_float one definitely seems AMD specific.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3454992f80dc582921784c16bce3d9b09e2ac041

commit 3454992f80dc582921784c16bce3d9b09e2ac041
Author: Ria Jiang <riajiang@chromium.org>
Date: Sat Apr 07 02:56:53 2018

Add flaky test expectations to webgl2_conformance_expectations.py.

TBR=kbr@chromium.org

Bug:  828984 
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I5ceef79309af52d7a9d2b154581495d955e48f3e
Reviewed-on: https://chromium-review.googlesource.com/1000764
Reviewed-by: Ria Jiang <riajiang@chromium.org>
Commit-Queue: Ria Jiang <riajiang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549020}
[modify] https://crrev.com/3454992f80dc582921784c16bce3d9b09e2ac041/content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

Found some more failures:
https://ci.chromium.org/buildbot/chromium.gpu.fyi/Win7%20FYI%20Release%20%28AMD%29/750
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win7%20FYI%20Release%20%28AMD%29/153
WebglConformance_conformance_renderbuffers_depth_renderbuffer_initialization

https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win7%20FYI%20Release%20%28AMD%29/154
WebglConformance_conformance2_renderbuffers_multisampled_depth_renderbuffer_initialization

https://ci.chromium.org/buildbot/chromium.gpu.fyi/Win7%20FYI%20Release%20%28AMD%29/791
WebglConformance_deqp_functional_gles3_samplerobject

https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win7%20FYI%20Release%20%28AMD%29/156
WebglConformance_conformance_glsl_functions_glsl_function_mod_float

Will add flaky expectations for those, too.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e2421424c1aeab735fa07ddc8eb1f57d53dc34e4

commit e2421424c1aeab735fa07ddc8eb1f57d53dc34e4
Author: Yuly Novikov <ynovikov@chromium.org>
Date: Thu Apr 12 01:02:10 2018

Mark Flaky more WebGL2 tests on Win AMD

deqp/functional/gles3/samplerobject.html
conformance/glsl/functions/glsl-function-mod-float.html
conformance/renderbuffers/depth-renderbuffer-initialization.html
conformance2/renderbuffers/multisampled-depth-renderbuffer-initialization.html

BUG= 828984 
TBR=kbr@chromium.org

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I25fc291bacac96c2b757081eff430f69e61fa00f
Reviewed-on: https://chromium-review.googlesource.com/1008826
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549982}
[modify] https://crrev.com/e2421424c1aeab735fa07ddc8eb1f57d53dc34e4/content/test/gpu/gpu_tests/webgl2_conformance_expectations.py