All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=615421

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg7PG2rgoM


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

chromium-rel-mac-hdd

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


=== Bisection aborted ===
The bisect was aborted because The metric values for the initial "good" and "bad" revisions do not represent a clear regression.
Please contact the the team (see below) if you believe this is in error.

=== Warnings ===
The following warnings were raised by the bisect job:

 * Bisect failed to reproduce the regression with enough confidence.

===== TESTED REVISIONS =====
Revision         Mean     Std Dev   N   Good?
chromium@395458  23.9663  0.30577   12  good
chromium@395514  24.2793  0.322081  12  bad

Bisect job ran on: mac_hdd_perf_bisect
Bug ID: 615421

Test Command: src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --also-run-disabled-tests smoothness.tough_canvas_cases
Test Metric: frame_times/frame_times
Relative Change: 1.11%
Score: 0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/mac_hdd_perf_bisect/builds/563
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9011494955713191264


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5791904554287104

| 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!

Trying a wider bisect.

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


=== Bisection aborted ===
The bisect was aborted because The metric values for the initial "good" and "bad" revisions do not represent a clear regression.
Please contact the the team (see below) if you believe this is in error.

=== Warnings ===
The following warnings were raised by the bisect job:

 * Bisect failed to reproduce the regression with enough confidence.

===== TESTED REVISIONS =====
Revision         Mean     Std Dev   N  Good?
chromium@395388  23.5093  0.268754  6  good
chromium@395514  24.2403  0.12629   4  bad

Bisect job ran on: mac_hdd_perf_bisect
Bug ID: 615421

Test Command: src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --also-run-disabled-tests smoothness.tough_canvas_cases
Test Metric: frame_times/frame_times
Relative Change: 3.71%
Score: 0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/mac_hdd_perf_bisect/builds/573
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9010209756733007680


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5838577863229440

| 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!

Trying a wider bisect again. We should close if it doesn't repro on the bisect bot.

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

Hi ericrk@chromium.org, the bisect results pointed to your CL below as possibly
causing a regression. Please have a look at this info and see whether
your CL be related.


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


===== SUSPECTED CL(s) =====
Subject : Enable GPU Raster for Mac waterfall
Author  : ericrk
Commit description:
  
This causes waterfall bots to run with GPU raster enabled while we
prepare to launch via Finch.

BUG=612275, 542959 

Review-Url: https://codereview.chromium.org/1992603002
Cr-Commit-Position: refs/heads/master@{#395445}
Commit  : f91789afe1568b37a4e93dfe0580c96df24137f6
Date    : Mon May 23 22:58:28 2016


===== TESTED REVISIONS =====
Revision         Mean     Std Dev    N  Good?
chromium@395346  23.41    0.313057   5  good
chromium@395430  23.4002  0.193831   5  good
chromium@395441  23.365   0.149726   8  good
chromium@395444  23.394   0.12092    8  good
chromium@395445  24.0688  0.0618524  5  bad    <--
chromium@395446  23.997   0.525763   8  bad
chromium@395451  24.1441  0.34288    8  bad
chromium@395472  24.064   0.0295517  5  bad
chromium@395514  24.1221  0.349457   8  bad

Bisect job ran on: mac_hdd_perf_bisect
Bug ID: 615421

Test Command: src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --also-run-disabled-tests smoothness.tough_canvas_cases
Test Metric: frame_times/frame_times
Relative Change: 3.17%
Score: 98.0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/mac_hdd_perf_bisect/builds/600
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9008941982858614608


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5828088693260288

| 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 should be fixed by crbug.com/2066733003 which blacklists the feature that was enabled by the blame CL on certain Macs (including this one). Additionally, it looks like this metric has been removed (data cuts off on 06/10).