748444 - eliminate relocations required by gHistograms

Status: RESOLVED FIXED

(Toolkit :: Telemetry, defect)

Description

[Nathan Froyd [:froydnj]]

bug 748417 is going to write a python script to parse TelemetryHistograms.h.  Once that's written, we should use the script to generate gHistograms at compile time; doing that will enable eliminating the pointers to names and descriptions (can simply use indices into a global char[] instead), reducing relocations and footprint.

Comment 1

[Nathan Froyd [:froydnj]]

Attachment: patch

I realize StringTable is a little overkill, but I copied the code directly from quickstubs, so I know it works, and if we start annotating histograms with units, we'll need something like StringTable anyway.  So I'd like to keep it around.

Comment 2

[(dormant account)]

Comment on attachment 656475 [details] [diff] [review]
patch

rubberstamp

Comment 3

[(dormant account)]

What are the footprint wins here?

Comment 4

[Nathan Froyd [:froydnj]]

(In reply to Taras Glek (:taras) from comment #3)
> What are the footprint wins here?

N histograms * (2 relocations + 1 word).  More than 1k bytes, less than 10k bytes on x86/ARM Linux.  Might be the same range for x86-64/Linux.  I imagine it's roughly the same on Windows and OS X, but not really sure.

Comment 5

[Nathan Froyd [:froydnj]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/a8b7d2524e94

Comment 6

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/a8b7d2524e94