1868530 - Lower parallel marking thresholds

Status: RESOLVED FIXED

(Core :: JavaScript: GC, task)

Description

[Jon Coppeard (:jonco)]

Following various bug fixes and improvements to parallel marking we should be able to lower the heap thresholds at which it is used.

Comment 1

[Jon Coppeard (:jonco)]

Attachment: Bug 1868530 - Lower parallel marking thresholds following recent improvements r?sfink

These thresholds were chosen based on local benchmarking results.

In general all macOS systems I've tested perform great and the 4MB threshold is
because none of the benchmarks I used have a heap smaller than that.

Recent Windows and Linux results are also better than previously although not
as good as macOS.

I haven't done any more Android benchmarking recently so I'm using the same
value as for Linux. We're not going to enable this on Android without specific
performance work there first.

For reference, according to telemetry about 10% of our GCs have < 1MB heap size
(the minimum size captured by telemetry). A 4MB threshold excludes 11.4% of
GCs, 8MB 14.3% and 16MB 24% of GCs.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a9bc32d2bf16
Lower parallel marking thresholds following recent improvements r=sfink

Comment 3

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/a9bc32d2bf16