1308506 - Investigate discrepancy between 64bit and 32bit on octane

Status: RESOLVED WORKSFORME

(Core :: JavaScript Engine: JIT, defect, P3)

Description

[Hannes Verschore [:h4writer]]

Seems that for some reason 64bit is slower than 32bit

>                                         32 bit      64bit
> Mandreel (octane 2.0.1 -- jmim)          27835      27889
> MandreelLatency (octane 2.0.1 -- jmim)   33684      33458
> DeltaBlue (octane 2.0.1 -- jmim)         62620      61754
> NavierStokes (octane 2.0.1 -- jmim)      36210      36249
> EarleyBoyer (octane 2.0.1 -- jmim)       38784      39358
> SplayLatency (octane 2.0.1 -- jmim)      21860      23185
> CodeLoad (octane 2.0.1 -- jmim)          17644      18003
> Crypto (octane 2.0.1 -- jmim)            30908      30448
> Splay (octane 2.0.1 -- jmim)             19234      18352
> Gameboy (octane 2.0.1 -- jmim)           60043      57490
> Typescript (octane 2.0.1 -- jmim)        27362      26382
> Box2D (octane 2.0.1 -- jmim)             40584      30874
> Richards (octane 2.0.1 -- jmim)          32488      32700
> RegExp (octane 2.0.1 -- jmim)             4120       4141
> PdfJS (octane 2.0.1 -- jmim)             13669      13952
> zlib (octane 2.0.1 -- jmim)              62171      61843
> RayTrace (octane 2.0.1 -- jmim)         115512     115660
> __total__ (octane 2.0.1 -- jmim)         30443      29890

I think I can categorize a little bit:

Has a lot of allocation (createthis) ?
DeltaBlue

Has a lot of compilation happening? Is that related?
Splay
Gameboy
Typescript

Just bi-modal things. We can ignore, this is just a bad run.
Box2D

Asm.js. Which is strange, because I thought asm.js is always faster on 64bit
zlib

Comment 1

[Luke Wagner [:luke]]

zlib is surprisingly microbenchmarky and pretty sensitive to small codegen difference.  I vaguely recall there might've been a regalloc/codegen that affected Octane-zlib last year that slipped through the cracks.  Might be good to do a quick test on old firefox and, if it's faster, bisect.

Comment 2

[Chris Peterson [:cpeterson]]

(In reply to Luke Wagner [:luke] from comment #1)
> zlib is surprisingly microbenchmarky and pretty sensitive to small codegen
> difference.  I vaguely recall there might've been a regalloc/codegen that
> affected Octane-zlib last year that slipped through the cracks.  Might be
> good to do a quick test on old firefox and, if it's faster, bisect.

I tried to bisect whether there was a 64-bit zlib regression since year, but I couldn't find one. Luckily (?) I found a zlib regression from just yesterday (from bug 1313180).

Comment 3

[Worcester12345]

(In reply to Hannes Verschore [:h4writer] from comment #0)

Seems that for some reason 64bit is slower than 32bit

                                    32 bit      64bit

Mandreel (octane 2.0.1 -- jmim) 27835 27889
MandreelLatency (octane 2.0.1 -- jmim) 33684 33458
DeltaBlue (octane 2.0.1 -- jmim) 62620 61754
NavierStokes (octane 2.0.1 -- jmim) 36210 36249
EarleyBoyer (octane 2.0.1 -- jmim) 38784 39358
SplayLatency (octane 2.0.1 -- jmim) 21860 23185
CodeLoad (octane 2.0.1 -- jmim) 17644 18003
Crypto (octane 2.0.1 -- jmim) 30908 30448
Splay (octane 2.0.1 -- jmim) 19234 18352
Gameboy (octane 2.0.1 -- jmim) 60043 57490
Typescript (octane 2.0.1 -- jmim) 27362 26382
Box2D (octane 2.0.1 -- jmim) 40584 30874
Richards (octane 2.0.1 -- jmim) 32488 32700
RegExp (octane 2.0.1 -- jmim) 4120 4141
PdfJS (octane 2.0.1 -- jmim) 13669 13952
zlib (octane 2.0.1 -- jmim) 62171 61843
RayTrace (octane 2.0.1 -- jmim) 115512 115660
total (octane 2.0.1 -- jmim) 30443 29890

I think I can categorize a little bit:

Has a lot of allocation (createthis) ?
DeltaBlue

Has a lot of compilation happening? Is that related?
Splay
Gameboy
Typescript

Just bi-modal things. We can ignore, this is just a bad run.
Box2D

Asm.js. Which is strange, because I thought asm.js is always faster on 64bit
zlib

How are your numbers now?

Comment 4

[Worcester12345]

?

Comment 5

[Wayne Mery (:wsmwk)]

Does this matter any more?

Comment 6

[Steven DeTar [:sdetar]]

Jan, could help answer this question

Comment 7

[Jan de Mooij [:jandem]]

Let's close this. A lot of things have changed, we no longer run Octane on 32-bit builds in CI, and all of our perf work is focused on 64-bit platforms these days.