1814798 - Allow PHC to be enabled by a pref

Status: RESOLVED FIXED

(Core :: Memory Allocator, enhancement, P2)

Description

[Paul Bone [:pbone]]

We'd like to enable PHC via a pref so that it can eventually be configured via Normandy and/or run on the Release channel. That also means being able to enable PHC late - after prefs have been read.

We could also let the parent process read the prefs and set environment variables for the child processes so they could enable it earlier.

Comment 1

[Paul Bone [:pbone]]

Attachment: Bug 1814798 - pt 1. Add bool to enable/disable PHC at runtime r=glandium

Add the ability to enable and disable PHC at runtime through the malloc
bridge.

Depends on D178752

Comment 2

[Paul Bone [:pbone]]

Attachment: Bug 1814798 - pt 2. Add a PHCManager component to control PHC r=glandium

Depends on D178753

Comment 3

[Paul Bone [:pbone]]

Attachment: Bug 1814798 - pt 3. Add new phc pref r=glandium

Add a new pref for controlling PHC. The pref can be changed at runtime and
will affect the parent and content processes.

Depends on D178754

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/bf7d386ad43a
pt 1. Add bool to enable/disable PHC at runtime r=glandium
https://hg.mozilla.org/integration/autoland/rev/50b72ab948b2
pt 2. Add a PHCManager component to control PHC r=glandium,emilio

Comment 5

[Serban Stanca [:SerbanS]]

Backed out for multiple phc related failures.

• Backout link

---

• Push with failures - XPCshell
• Failure Log
• Failure line: TEST-UNEXPECTED-FAIL | toolkit/crashreporter/test/unit/test_crash_phc.js | xpcshell return code: 0

---

• Push with failures - gtest
• Failure Log
• Failure line: PROCESS-CRASH | MOZ_CRASH(failed to get a PHC allocation) [@ PHC_TestPHCAllocations_Test::TestBody] | gtest

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/3064abbb72eb
pt 1. Add bool to enable/disable PHC at runtime r=glandium
https://hg.mozilla.org/integration/autoland/rev/4045e1720c33
pt 2. Add a PHCManager component to control PHC r=glandium,emilio

Comment 7

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/3064abbb72eb
https://hg.mozilla.org/mozilla-central/rev/4045e1720c33

Comment 8

[Andra Esanu (needinfo me)]

(In reply to Pulsebot from comment #6)

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/3064abbb72eb
pt 1. Add bool to enable/disable PHC at runtime r=glandium
https://hg.mozilla.org/integration/autoland/rev/4045e1720c33
pt 2. Add a PHCManager component to control PHC r=glandium,emilio

== Change summary for alert #39633 (as of Thu, 21 Sep 2023 11:49:59 GMT) ==

Improvements:

Ratio	Test	Platform	Options	Absolute values (old vs new)	Performance Profiles
3%	wikipedia loadtime	macosx1015-64-shippable-qr	bytecode-cached fission warm webrender	369.71 -> 358.95	Before/After
3%	wikipedia loadtime	macosx1015-64-shippable-qr	bytecode-cached fission warm webrender	370.13 -> 359.85	Before/After
2%	wikipedia fcp	macosx1015-64-shippable-qr	cold fission webrender	556.38 -> 543.03	Before/After

For up to date results, see: https://treeherder.mozilla.org/perfherder/alerts?id=39633

Comment 9

[Markus Stange [:mstange]]

These patches turned off PHC on Nightly and improved performance. Was this intentional?

Comment 10

[Paul Bone [:pbone]]

(In reply to Markus Stange [:mstange] from comment #9)

These patches turned off PHC on Nightly and improved performance. Was this intentional?

Thanks. I've filed Bug 1856268