1772894 - Only report GCs as full (non-zonal) if they are explicitly requested to be full

Status: RESOLVED FIXED

(Core :: JavaScript: GC, enhancement, P1)

Description

[Steve Fink [:sfink] [:s:]]

Currently the GC telemetry (gc_is_compartmental) will report a GC as full if 100% of zones are collected. One way for that to happen is for a full GC to be requested. Another way is for all zones to be scheduled for different reasons.

It looks like it would be more useful to base the definition off of the explicit request. For example, when tracking down why some change results in more full GCs, the happenstance full GCs are confusing—if I'm looking at a profile and seeing a bunch of full GCs, then I'll need to figure out whether they were requested to be full or happened to be full. Also, if there are a small number of Zones, then you'll be likely to see a higher percentage of full GCs by happenstance. (Which means for example that fission will increase the percentage of full GCs without any changes in scheduling logic.)

This is mostly an issue with telemetry and profile markers.

Comment 1

[Steve Fink [:sfink] [:s:]]

Attachment: Bug 1772894 - Report noncompartmental aka nonzonal aka full GCs only when a full GC is requested, even if 100% of zones end up collecting

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/28628b207b56
Report noncompartmental aka nonzonal aka full GCs only when a full GC is requested, even if 100% of zones end up collecting r=jonco

Comment 3

[Marian-Vasile Laza]

https://hg.mozilla.org/mozilla-central/rev/28628b207b56