1514281 - Investigate not throwing away so much code on GC

Status: ASSIGNED

(Core :: JavaScript: GC, enhancement, P3)

Description

[Jon Coppeard (:jonco)]

See bug 1498485 comment 25.

I don't remember what the exact policy is right now, but we should try and keep recently used compiled code around to avoid repeatedly regenerating it.

Comment 1

[Andrew Overholt [:overholt]]

Jon, is it possible to push a try build that just doesn't throw away compiled code (and therefore intentionally leaks)? Anthony was speculating this might show whether or not changing this policy would make a big difference for bug 1498485 or not.

Comment 2

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

I will give that a try while Jon's out.

Comment 3

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

Attachment: Experiment with almost never discarding JIT code

try push with what I *think* should do it:

https://treeherder.mozilla.org/#/jobs?repo=try&revision=77000d8e53f569a9e1997c24f814de9232b3c459

Note that we already shouldn't be discarding code if we've animated in the last second, as per https://searchfox.org/mozilla-central/source/js/src/gc/GC.cpp#3994-3997 , but perhaps something else is kicking in?

Comment 4

[Jon Coppeard (:jonco)]

(In reply to Steve Fink [:sfink] [:s:] from comment #3)
Did this experiment produce any results?

Comment 5

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

(In reply to Jon Coppeard (:jonco) from comment #4)

Did this experiment produce any results?

I produced the build, but was relying on someone else to try it out. Note that it was buggy in some way -- the try push had a number of errors that I never looked into; I just hoped it was functional enough to get some performance numbers out of.

So: no, no results.