All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=646915

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgmfS-pAkM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgmaGspwoM


Bot(s) for this bug's original alert(s):

chromium-rel-mac11

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9001525021559721248

Bisect failed: http://build.chromium.org/p/tryserver.chromium.perf/builders/mac_10_11_perf_bisect/builds/897
Failure reason: the build has failed.
Additional errors:
The metric was not found in the test output.
Either of the initial "good" or "bad" revisions failed to be tested or built.

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9001510120935443040

Bisect failed: http://build.chromium.org/p/tryserver.chromium.perf/builders/mac_10_11_perf_bisect/builds/897
Failure reason: the build has failed.
Additional errors:
The metric was not found in the test output.
Either of the initial "good" or "bad" revisions failed to be tested or built.

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9001415757668874288

Bisect failed: http://build.chromium.org/p/tryserver.chromium.perf/builders/mac_10_11_perf_bisect/builds/908
Failure reason: the build has failed.
Additional errors:
The metric was not found in the test output.
Either of the initial "good" or "bad" revisions failed to be tested or built.

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9000766478061240000

===== BISECT JOB RESULTS =====
Status: failed


===== TESTED REVISIONS =====
Revision         Mean     Std Dev   N  Good?
chromium@418028  70.9101  0.941907  8  good
chromium@418054  72.3872  0.896637  8  bad
chromium@418079  75.2279  5.01152   8  bad

Bisect job ran on: mac_10_11_perf_bisect
Bug ID: 646915

Test Command: src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --also-run-disabled-tests page_cycler_v2.intl_es_fr_pt-BR
Test Metric: timeToFirstMeaningfulPaint_avg/pcv1-warm/http___produto.mercadolivre.com.br_MLB-468424957-pelicula-protetora-smartphone-h5500-e-h5300-43-frete-free-_JM
Relative Change: 6.10%
Score: 0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/mac_10_11_perf_bisect/builds/919
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9001525021559721248


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5024444727164928

| O O | Visit http://www.chromium.org/developers/speed-infra/perf-bug-faq
|  X  | for more information addressing perf regression bugs. For feedback,
| / \ | file a bug with component Tests>AutoBisect.  Thank you!

perf fixit: unassigning owner for sheriff-owned bugs to clarify that these are triaged by a rotation.

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8994368661842393824

=== PERF REGRESSION ===


=== Auto-CCing suspected CL author enne@chromium.org ===

Hi enne@chromium.org, the bisect results pointed to your CL, please take a look at the
results.


===== BISECT JOB RESULTS =====
Status: completed


===== SUSPECTED CL(s) =====
Subject : Remove uses of external begin frame sources
Author  : enne
Commit description:
  
With this change, all output surfaces in the renderer provide begin
frame sources directly rather than via an additional parameter to
the LayerTreeHost.

The functional difference between these two paths is that the external
begin frame source exists for the lifetime of the compositor, whereas
the output surface begin frame source is only provided between
BindToClient / DetachFromClient.  The cc::Scheduler is already robust
to these changes and the browser compositor already uses this logic.

The output surface path is more useful in the browser where the output
surface may change which begin frame source it is providing.  However,
this patch just modifies the renderer to use the same path as the
browser so there's only one way of doing things.

In this patch, any time a CompositorOutputSurface or
SynchronousCompositorOutputSurface would be used, RenderThreadImpl
passes it the CompositorExternalBeginFrameSource that would have been
used as the external begin frame source parameter.

The other cases of output surface creation do not need an external begin
frame source.  Layout tests composite synchronously without a
cc::Scheduler and so do not need one.  ui::OutputSurface for mus
renderers internally creates its own default begin frame source (for now).
Blimp doesn't create an output surface so no longer needs special
case code for an external begin frame source that it also doesn't use.

The external begin frame source setting and plumbing is not cleaned up
in this patch and will be done in a followup.

CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_precise_blink_rel

Review-Url: https://codereview.chromium.org/2299003002
Cr-Commit-Position: refs/heads/master@{#418040}
Commit  : 077ba4863c28cbcb1049c24148aeae09f1dfa646
Date    : Mon Sep 12 21:01:34 2016


===== TESTED REVISIONS =====
Revision         Mean     Std Dev  N   Good?
chromium@418028  71.9689  8.26826  18  good
chromium@418034  131.194  1573.89  27  good
chromium@418035  189.422  2151.55  27  unknown
chromium@418038  71.1576  1.73648  8   good
chromium@418039  71.7438  1.74116  12  good
chromium@418040  209.749  1549.6   12  bad      <--
chromium@418041  74.6148  12.1761  18  bad
chromium@418054  74.4382  13.2449  27  bad
chromium@418079  76.0736  9.8922   18  bad

Bisect job ran on: mac_10_11_perf_bisect
Bug ID: 646915

Test Command: src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=http...produto.mercadolivre.com.br.MLB.468424957.pelicula.protetora.smartphone.h5500.e.h5300.43.frete.free..JM page_cycler_v2.intl_es_fr_pt-BR
Test Metric: timeToFirstContentfulPaint_avg/pcv1-warm/http___produto.mercadolivre.com.br_MLB-468424957-pelicula-protetora-smartphone-h5500-e-h5300-43-frete-free-_JM
Relative Change: 4.38%

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/mac_10_11_perf_bisect/builds/1088
Job details: https://chromeperf.appspot.com/buildbucket_job_status/8994368661842393824


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=6421139398590464

| O O | Visit http://www.chromium.org/developers/speed-infra/perf-bug-faq
|  X  | for more information addressing perf regression bugs. For feedback,
| / \ | file a bug with component Tests>AutoBisect.  Thank you!

This is a tiny blip from months ago and the graph has hugely improved since then.

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8982659713415344912

=== BISECT JOB RESULTS ===
NO Perf regression found

Bisect Details
  Configuration: mac_10_11_perf_bisect
  Benchmark    : page_cycler_v2.intl_es_fr_pt-BR
  Metric       : timeToFirstContentfulPaint_avg/pcv1-warm/http___produto.mercadolivre.com.br_MLB-468424957-pelicula-protetora-smartphone-h5500-e-h5300-43-frete-free-_JM

Revision             Result                  N
chromium@418028      74.5614 +- 20.9146      21      good
chromium@418079      76.1465 +- 13.823       21      bad

To Run This Test
  src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=http...produto.mercadolivre.com.br.MLB.468424957.pelicula.protetora.smartphone.h5500.e.h5300.43.frete.free..JM page_cycler_v2.intl_es_fr_pt-BR

Debug Info
  https://chromeperf.appspot.com/buildbucket_job_status/8982659713415344912

Is this bisect wrong?
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5024444727164928


| O O | Visit http://www.chromium.org/developers/speed-infra/perf-bug-faq
|  X  | for more information addressing perf regression bugs. For feedback,
| / \ | file a bug with component Speed>Bisection.  Thank you!