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Issue metadata

Status: WontFix
Owner:
Closed: Dec 2016
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: ----
Pri: 2
Type: Bug-Regression

Blocked on:
issue 670062



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3.1%-7.6% regression in speedometer at 433078:433157

Project Member Reported by hablich@chromium.org, Nov 29 2016

Issue description

See the link to graphs below.
 
Project Member

Comment 3 by 42576172...@developer.gserviceaccount.com, Nov 29 2016

Cc: v8-autoroll@chromium.org
Owner: v8-autoroll@chromium.org

=== Auto-CCing suspected CL author v8-autoroll@chromium.org ===

Hi v8-autoroll@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 : Version 5.6.326
Author  : v8-autoroll
Commit description:
  
Performance and stability improvements on all platforms.

Cr-Commit-Position: refs/heads/5.6.326@{#1}
Cr-Branched-From: 879f6599eee6e1dfcbe9a24bf688b261c03e9558-refs/heads/master@{#41014}
Commit  : bdd3886218dfe76e8560eb8a18401942452ae859
Date    : Wed Nov 16 00:11:09 2016


===== TESTED REVISIONS =====
Revision                       Mean     Std Dev  N   Good?
chromium@433133                678.803  186.77   50  good
chromium@433134                679.284  188.702  50  good
chromium@433134,v8@bdd3886218  720.76   133.555  50  bad    <--
chromium@433135                722.547  131.283  50  bad
chromium@433137                714.266  136.736  50  bad

Bisect job ran on: winx64nvidia_perf_bisect
Bug ID: 669505

Test Command: src/tools/perf/run_benchmark -v --browser=release_x64 --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests speedometer
Test Metric: EmberJS-TodoMVC/EmberJS-TodoMVC
Relative Change: 5.22%

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/winx64nvidia_perf_bisect/builds/1959
Job details: https://chromeperf.appspot.com/buildbucket_job_status/8994654106808428960


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5829032992571392

| 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!
Cc: -v8-autoroll@chromium.org sullivan@chromium.org machenb...@chromium.org
Owner: ----
Any clue why it didn't step into the roll?
Can you restart the bisect? Otherwise please file a separate bug for bisect not stepping into V8.
Cc: simonhatch@chromium.org
+simonhatch can you take a look at why it didn't step into the roll? I'll kick off an additional bisect.
Project Member

Comment 8 by 42576172...@developer.gserviceaccount.com, Nov 30 2016


===== BISECT JOB RESULTS =====
Status: started


===== TESTED REVISIONS =====
Revision         Mean     Std Dev  N   Good?
chromium@433121  752.817  189.312  50  good
chromium@433130  761.929  183.771  50  good
chromium@433134  757.603  141.35   50  good
chromium@433135  809.467  117.114  50  bad
chromium@433136  809.598  113.99   50  bad
chromium@433138  808.605  149.749  50  bad
chromium@433154  814.434  116.29   50  bad

Bisect job ran on: mac_retina_perf_bisect
Bug ID: 669505

Test Command: src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests speedometer
Test Metric: EmberJS-TodoMVC/EmberJS-TodoMVC
Relative Change: 8.18%

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/mac_retina_perf_bisect/builds/1848
Job details: https://chromeperf.appspot.com/buildbucket_job_status/8994561278661195536


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5337262592622592

| 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!
The commit message is a bit misleading, because it looks like that V8 roll was actually a rollback:

https://chromium.googlesource.com/chromium/src/+/b3028836333034e1bffde377a017d3026069ec6e

Update the V8 version for Chromium branch 56.

This is a roll-back to 5.6.326. This is the most stable candidate out of the latest Canaries.

If this commit results in failures in Blink please contact the Blink sheriff. They may need to make changes to Blink because of the roll-back.

When in doubt please try to contact the committer and reviewers of this CL before reverting it.

TBR=vogelheim@chromium.org

Review-Url: https://codereview.chromium.org/2508043003
Cr-Commit-Position: refs/heads/master@{#433135}


I think in this case the bisect needs to be clear about what happened, logged crbug.com/670062
Owner: simonhatch@chromium.org
Status: Assigned (was: Untriaged)
Ah right. Then this is simple. Also the graphs have recovered:
https://chromeperf.appspot.com/report?sid=abee31cc6ef51ddd123a049fc235d39b212b63290cc5d50466bc43d94845ef88&rev=433138

1. V8 made an improvement.
2. V8 was rolled back behind the improvement for the branch (flagged here as regression).
3. After the branch V8 rolled forward and the improvement got in again.

This is basically wontfix, you can mark it as such. I keep it open for minor remarks:


1. Bisect actually dived in one step and reported in comment 3:
https://chromium.googlesource.com/v8/v8/+/bdd3886218dfe76e8560eb8a18401942452ae859
instead of
https://chromium.googlesource.com/chromium/src/+/b3028836333034e1bffde377a017d3026069ec6e
The latter one, at least as additional information would have been helpful.

2. The link in comment 3 resolves to chromium/src instead of v8/v8 which must be adjusted manually.
Status: WontFix (was: Assigned)
Blockedon: 670062

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