All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=802400

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=8d58778de260f6ac94eab962051b8cf2ff138f6c13fb4cb0e6ed0b656895d438


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

android-webview-nexus5X

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8957208444973936160

=== Auto-CCing suspected CL author jwolfe@igalia.com ===

Hi jwolfe@igalia.com, the bisect results pointed to your CL, please take a look at the
results.


=== BISECT JOB RESULTS ===
Perf regression found with culprit

Suspected Commit
  Author : Josh Wolfe
  Commit : 6fe75e30aacff1f2e9b10a01e20bebd68fe56474
  Date   : Wed Jan 10 17:29:46 2018
  Subject: Reland: Enable --harmony-function-tostring by default

Bisect Details
  Configuration: android_webview_arm64_aosp_perf_bisect
  Benchmark    : system_health.memory_mobile
  Metric       : memory:webview:all_processes:reported_by_chrome:v8:effective_size_avg/load_search/load_search_baidu
  Change       : 5.58% | 4670377.33333 -> 4930936.0

Revision                           Result                  N
chromium@528458                    4670377 +- 39432.9      6      good
chromium@528461                    4711927 +- 228852       6      good
chromium@528463                    4678709 +- 24891.5      6      good
chromium@528463,v8@ff0abec84c      4668805 +- 21100.6      6      good
chromium@528463,v8@73253d428c      4666848 +- 46944.2      6      good
chromium@528463,v8@6fe75e30aa      4967500 +- 44763.0      6      bad       <--
chromium@528464                    4952727 +- 59116.1      6      bad
chromium@528469                    4970136 +- 133642       6      bad
chromium@528479                    4944940 +- 60129.3      6      bad
chromium@528500                    4930936 +- 26529.5      6      bad

Please refer to the following doc on diagnosing memory regressions:
  https://chromium.googlesource.com/chromium/src/+/master/docs/memory-infra/memory_benchmarks.md

To Run This Test
  src/tools/perf/run_benchmark -v --browser=android-webview --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=load.search.baidu system_health.memory_mobile

More information on addressing performance regressions:
  http://g.co/ChromePerformanceRegressions

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8957208444973936160


For feedback, file a bug with component Speed>Bisection

Issue 803270 has been merged into this issue.

Likely similar to  issue 801556 , will investigate.

adamk: Perf sheriff checking in. Any update on this bug?

I've been learning-to-use/trying-to-understand infrastructure over on the linked bug to try to pin this down, so far without luck (my Pinpoint run's data doesn't make any sense). I'll give another shot at reproducing (probably locally) today.

An interesting thing with this regression is that the magnitude looks very similar to other recent progressions in the same metric, both before and after this change. It would be interesting to run bisects of those progressions to see if the blamed CLs seem particularly related, or whether they suggest some measurement artifact in this test.

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/483c0313c3cda06c0422f5c33289e69fe5a151df

commit 483c0313c3cda06c0422f5c33289e69fe5a151df
Author: Adam Klein <adamk@chromium.org>
Date: Wed Jan 31 23:14:42 2018

Revert "Reland: Enable --harmony-function-tostring by default"

This reverts commit 6fe75e30aacff1f2e9b10a01e20bebd68fe56474.

Enabling this flag caused a number of memory and performance
regressions, so disabling on the 6.5 branch while I try to fix
on tip-of-tree.

Bug:  v8:4958 ,  chromium:801556 ,  chromium:802400 , chromium:807192
Change-Id: Id5a2bb5362038f19140ba995af56bee6b1cf5b4f
Reviewed-on: https://chromium-review.googlesource.com/896168
Reviewed-by: Michael Hablich <hablich@chromium.org>
Cr-Commit-Position: refs/branch-heads/6.5@{#19}
Cr-Branched-From: 73c55f57fe8506011ff854b15026ca765b669700-refs/heads/6.5.254@{#1}
Cr-Branched-From: 594a1a0b6e551397cfdf50870f6230da34db2dc8-refs/heads/master@{#50664}
[modify] https://crrev.com/483c0313c3cda06c0422f5c33289e69fe5a151df/src/flag-definitions.h
[modify] https://crrev.com/483c0313c3cda06c0422f5c33289e69fe5a151df/test/message/fail/paren_in_arg_string.out
[modify] https://crrev.com/483c0313c3cda06c0422f5c33289e69fe5a151df/test/mjsunit/harmony/async-generators-basic.js
[modify] https://crrev.com/483c0313c3cda06c0422f5c33289e69fe5a151df/test/mjsunit/regress/regress-2470.js
[modify] https://crrev.com/483c0313c3cda06c0422f5c33289e69fe5a151df/test/mjsunit/regress/regress-crbug-109362.js
[modify] https://crrev.com/483c0313c3cda06c0422f5c33289e69fe5a151df/test/mjsunit/regress/regress-crbug-663410.js
[modify] https://crrev.com/483c0313c3cda06c0422f5c33289e69fe5a151df/test/mozilla/mozilla.status

I've reverted the flag flip on the 6.5 branch, will continue to investigate on tip-of-tree. Marking as a release-blocker for M66 so this doesn't get dropped on the floor.

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/537e89a350f2b5642aab3980c88a5a5adea94fa3

commit 537e89a350f2b5642aab3980c88a5a5adea94fa3
Author: Adam Klein <adamk@chromium.org>
Date: Fri Feb 02 18:13:22 2018

Fix eval cache with --harmony-function-tostring

The code was using the "correct" cache key for lookups, but not for
creating new entries, leading to us never hitting the cache for
some Function-constructor cases.

Bug:  v8:4958 ,  chromium:801556 ,  chromium:802400 , chromium:807192
Change-Id: I4ac2234b97a9f5f71957ef936dc4b588d020916b
Reviewed-on: https://chromium-review.googlesource.com/898096
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51081}
[modify] https://crrev.com/537e89a350f2b5642aab3980c88a5a5adea94fa3/src/compiler.cc

Graph seems to have recovered, though I can't quite find my patch as a definitive cause.