1743322 - Speed up arena_run_reg_dalloc

Status: RESOLVED FIXED

(Core :: Memory Allocator, enhancement, P1)

Description

[Paul Bone [:pbone]]

The FastDivide code here isn't actually faster than just doing a division. At least on my Skylake system. It's probably still better in some systems.

I've found that I can speed this code up further by eluding the branches we use to decide how to divide.

Comment 1

[Paul Bone [:pbone]]

Attachment: Bug 1743322 - Remove branches that decide how to divide r=glandium

Comment 2

[Paul Bone [:pbone]]

Attachment: Bug 1743322 - Make arena_bin_t 32 or 48 bytes long r=glandium

Make mRunSize the number of pages in a run rather than bytes, so that it can
be stored in a single byte and save some space in bin headers.

Depends on D132322

Comment 3

[Paul Bone [:pbone]]

Attachment: Bug 1743322 - Rename FastDivsion and add an operator overload r=glandium

Depends on D140036

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/25647d613534
Remove branches that decide how to divide r=glandium
https://hg.mozilla.org/integration/autoland/rev/d299fa6358f7
Make arena_bin_t 32 or 48 bytes long r=glandium

Comment 5

[Norisz Fay [:noriszfay]]

Backed out for causing multiple failures

Backout link

Push with failures

Failure log 1
Failure log 2

Seems that it only happened on OS X 11 WebRender Shippable.

Comment 6

[Paul Bone [:pbone]]

I forgot to test on ARM64, especially M1 whose pagesize is larger and therefore the division constants I chose don't work

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/3a6e4adf6853
Remove branches that decide how to divide r=glandium
https://hg.mozilla.org/integration/autoland/rev/72ad95ef4cde
Make arena_bin_t 32 or 48 bytes long r=glandium
https://hg.mozilla.org/integration/autoland/rev/febef97c7fbe
1743322: apply code formatting via Lando

Comment 8

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/3a6e4adf6853
https://hg.mozilla.org/mozilla-central/rev/72ad95ef4cde
https://hg.mozilla.org/mozilla-central/rev/febef97c7fbe