All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=643198

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg4cab-AgM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgoeGrqAkM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgwb2V-woM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg4ayMowoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgoavp4AgM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgoYyQhQkM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgwb2V-wgM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg4Yj-pAoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgoc3-oQsM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgobP5rAkM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgoe-1oQoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg4azQvAoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgoe-hvwoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg4bm_qQoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgoZu4qgkM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg4dLFuQsM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgoZGO7AoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg4eCAoAkM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgof2ZowoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg4cTloAsM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg4fb0rQkM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg4crZtgoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgoYyz4gsM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgobnB4ggM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg4d2PpQoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgweyr9AsM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgoZeBsQkM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg4dbztwoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgodyc9QgM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgofyLrQsM


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

android-galaxy-s5
android-nexus6
android-nexus9
chromium-rel-mac-retina
chromium-rel-mac10
chromium-rel-mac11
chromium-rel-win7-dual
chromium-rel-win7-gpu-nvidia
linux-release

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9002612770838467920

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9002612762345239264

kouhei@: There are quite a few big regressions in page_cycler_v2 recently, and bisects are always failing to find the cause(s). I am assigning the bugs to you since you seem to have made many (most?) PCv2 changed recently. If I am wrong, could you please help me find the right owner of these bugs?

Bisect failed: http://build.chromium.org/p/tryserver.chromium.perf/builders/android_nexus6_perf_bisect/builds/2536
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.

Bisect failed: http://build.chromium.org/p/tryserver.chromium.perf/builders/android_nexus6_perf_bisect/builds/2535
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/9000176898201868464

ksakamoto: I see this in the revision range, could it be the cause for the change?
2016-08-30 ksakamoto Update FirstMeaningfulPaint to use Blink's implementation

Yes my change must be the cause for this; it changes FMP value drastically on some pages.

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


===== SUSPECTED CL(s) =====
Subject : Update FirstMeaningfulPaint to use Blink's implementation
Author  : ksakamoto
Commit description:
  
Note to perf sheriffs: this is going to affect timeToFirstMeaningfulPaint
values in page_cycler_v2 benchmarks.

This updates FirstMeaningfulPaint metric to use trace events logged by
Blink's FirstMeaningfulPaintDetector, instead of computing layout
significance from FrameView::performLayout trace event.

Since Blink implementation counts more layout objects / uses the end
time of the paint phase, this patch will change TTFMP value, but it
increases accuracy (see  https://crbug.com/638124#c8  for details).

This requires the new trace event added in https://crrev.com/2276573003/.

BUG= chromium:638124 

Review-Url: https://codereview.chromium.org/2259723002
Commit  : 7bf2ae5c26055537f6c07d88d15d29485bca65b1
Date    : Wed Aug 31 01:50:43 2016


===== TESTED REVISIONS =====
Revision                             Mean     Std Dev  N  Good?
chromium@415621                      890.494  17.0437  5  good
chromium@415624                      894.552  14.4167  5  good
chromium@415624,catapult@e403ae0791  892.082  9.4746   5  good
chromium@415624,catapult@17bda7618b  901.457  22.2923  5  good
chromium@415624,catapult@dccd40a985  890.567  16.3982  5  good
chromium@415624,catapult@7bf2ae5c26  1405.94  15.7303  5  bad    <--
chromium@415625                      1413.39  26.6171  5  bad
chromium@415626                      1401.95  14.2115  5  bad
chromium@415627                      1407.98  15.7058  5  bad
chromium@415632                      1408.49  18.9131  5  bad
chromium@415642                      1421.21  34.3954  5  bad

Bisect job ran on: android_nexus5_perf_bisect
Bug ID: 643198

Test Command: src/tools/perf/run_benchmark -v --browser=android-chromium --output-format=chartjson --upload-results --also-run-disabled-tests page_cycler_v2.intl_ko_th_vi
Test Metric: timeToFirstMeaningfulPaint_avg/pcv1-warm/http___kenh14.vn_home.chn
Relative Change: 59.60%
Score: 99.9

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/android_nexus5_perf_bisect/builds/4162
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9000176898201868464


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5013101609484288

| 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!

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8982584513897873696