952393 - Move never changed data to a separated section for more data sharing

Status: RESOLVED WONTFIX

(Firefox OS Graveyard :: GonkIntegration, defect)

Description

[Thinker Li [:sinker]]

With Nuwa, a lot of data is potential to be shared among content processes.  But, pages that includes changed values, even only one byte, can not be shared.  If we could analyze run time data section, to find out variables that is potential no changed by apps, we could move these variables into a separated data section for later build to share more pages.

The idea is:
 1. use readelf or other tools to read out all symbols of libxul and other shared objects.
 2. collect values in data sections of the Nuwa process.
 3. collect values in data sections of app processes.
 4. compare data sections of app processes against the Nuwa process.
 4. find out values untouched and their respective symbols.
 5. move these symbols to a separated sections for later builds.

Potential issues
 1. impact memory cache?
 2. how to move variables to a separated section?
    - link scripts
    - variable attributes

Comment 1

[[:fabrice] Fabrice Desré]

Is that similar to what jld is planning to do in bug 948648 ?

Comment 2

[Thinker Li [:sinker]]

Yes!  This one aims on moving variables to a separated section.  The result of bug948648 can be feed to this bug.

Comment 3

[James Zhang (Spreadtrum)]

Good idea. We can do more things like android zygote.

Comment 4

[Joe Cheng [:jcheng] (please needinfo)]

is it possible that your team can contribute on this fix? thanks

Comment 5

[BMO Automation]

Firefox OS is not being worked on