All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=903197

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=a8972b6216245d98047369f972a108c3ac796faf893634eb800a3a1aed14ed8a


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

Android Nexus6 WebView Perf
mac-10_13_laptop_high_end-perf

jetstream - Benchmark documentation link:
  None

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/15c48807e40000

📍 Found a significant difference after 1 commit.
https://pinpoint-dot-chromeperf.appspot.com/job/15c48807e40000

[wasm] Enable node splitting during scheduling. by mstarzinger@chromium.org
https://chromium.googlesource.com/v8/v8/+/fc755be9dabf896a23ca0131cd1c24806e81a2d2
Score: 187.3 → 183.6 (-3.733)

Understanding performance regressions:
  http://g.co/ChromePerformanceRegressions

Benchmark documentation link:
  None

Seems to be cause by activating node splitting for WebAssembly.

There are several line-items in JetStream that improve (e.g. quicksort, zlib, ...) and several that regress, the most noteworthy being n-body. It is interesting though that the only affected n-body benchmark seems to be asm.js, the JS as well as the WebAssembly version look unaffected.

One option would be to disable node splitting specifically for asm.js code.

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/631dd28db8d3a7fd970cf093cc3ac399890462a9

commit 631dd28db8d3a7fd970cf093cc3ac399890462a9
Author: Michael Starzinger <mstarzinger@chromium.org>
Date: Fri Nov 09 13:38:29 2018

[wasm] Disable node splitting for asm.js code.

R=herhut@chromium.org
BUG= chromium:903197 

Change-Id: Ibc9225afe4237f221ae169de3ce6b3abb45e2708
Reviewed-on: https://chromium-review.googlesource.com/c/1328925
Reviewed-by: Stephan Herhut <herhut@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57390}
[modify] https://crrev.com/631dd28db8d3a7fd970cf093cc3ac399890462a9/src/compiler/pipeline.cc
[modify] https://crrev.com/631dd28db8d3a7fd970cf093cc3ac399890462a9/src/optimized-compilation-info.cc

The JetStream score should recover after the above change. I'll keep this bug open until we have confirmation.

Issue 903311 has been merged into this issue.

The regressions in n-body recovered.