940125 - Substantial regression in Octane v2 - MandreelLatency between FF22 and FF25

Status: NEW

(Core :: JavaScript Engine, defect)

Description

[Naveed Ihsanullah [:naveed]]

My numbers:
Firefox 22 - 57,301 
Firefox 25 -  40,203

Octane v2 is very new and not on AWFY yet. I discovered this while doing some manual benchmarking. So far every regression between FF22 and FF23 has been related to the loss of JM and large function size so that may be a place to start.

Comment 1

[Nicolas B. Pierron [:nbp]]

I confirm, we already saw this issue in other code base, and the lack of chunk compilation in IonMonkey is often related to this issue.  Still, this should be less of a problem since Brian enabled large function compilation on the background thread (Bug 886957), which should already be part of Gecko 25.

Jan tried to add chunk compilation to IonMonkey about a year ago, but the extra complexity added was hard to grasp from what I understood.

Kannan recently opened Bug 937647 to suggest doing chunk compilation per-loop.

Comment 2

[Jan de Mooij [:jandem]]

Just to be clear, we don't know at all whether this is caused by function size and chunked compilation. It could be, but there can be many other reasons (see bug 940062 for instance).