bug#31138: Native json slower than json.el

[Dmitry Gutov]

On 16.04.2019 18:13, Eli Zaretskii wrote:

> Thanks.  I think we need to run this with a larger JSON, or maybe run
> it several times in a loop.

There's a loop in benchmark already (10 times).

> Because there were too few samples in
> this run, so we might see a biased picture due to overhead of stuff
> that is done only once.

I've increased it to 100 (the process now takes 38 seconds here).

perf also has a sampling frequency parameter (still 99 Hz used).

> Also, please set gc-cons-threshold and gc-cons-percentage to very
> large values, to prevent GC from biasing the profile even more.

gc-cons-percentage says it's ignored when gc-cons-threshold is high 
enough. I've increased the latter.

> > If you have certain recording or output format preferences, please let
> > me know.
>
> The ASCII format is fine.

It can add extra columns or some such.

> Was this an optimized build of Emacs or an unoptimized one?

What compiler should emacs be built with?               gcc -g3 -O2

The script and report are attached.

perf-report.txt
Description: Text document

json-test.el
Description: Text Data