811132 - Avoid some wasted space by making XPT arena chunks bigger.

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Nicholas Nethercote [inactive]]

The XPT arena chunk size is currently 1 KiB.  I experimented with making it 
bigger, to see if it reduced the size of "explicit/xpti-working-set".

chunk size      desktop64       b2g-desktop64
----------      ---------       -------------
  1 KiB         1,702,096 B     1,639,632 B 
  4 KiB         1,618,128 B     1,560,784 B
  8 KiB         1,581,264 B     1,532,112 B
 16 KiB         1,573,072 B     1,523,920 B
 32 KiB         1,573,072 B     1,507,536 B
 64 KiB         1,605,840 B     1,540,304 B

The best size was 32 KiB for both cases.

Comment 1

[Nicholas Nethercote [inactive]]

Attachment: Avoid some wasted space by making XPT arena chunks bigger.

In this patch I've used 16 KiB because the allocation sizes are a bit smaller
on 32-bit (e.g. bug 802446 says that on b2g xpti-working-set is currently
1,152,128 bytes).  So I'm guessing this will be roughly a 70--80 KiB
per-process win on b2g, at least until bug 799658 is done.

Comment 2

[Justin Lebar (not reading bugmail)]

Comment on attachment 680847 [details] [diff] [review]
Avoid some wasted space by making XPT arena chunks bigger.

Simple change, beneficial on desktop even.  a=me

Comment 3

[Nicholas Nethercote [inactive]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/2ee6655b6da1

Comment 4

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/2ee6655b6da1

Comment 5

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/4507fdd47ab2