Re: master afc0bfd380: Speed up loaddefs-generate on slow disks

[Mattias Engdegård]

4 juni 2022 kl. 14.30 skrev Lars Ingebrigtsen <larsi@gnus.org>:

> I ran this three times and picked the median build time for each date,
> and viola:  https://quimby.gnus.org/circus/stats-emacs/build-times.html

Thank you! I picked a few edges that looked like transitions to a higher 
plateau and tried to find the culprit in the logs, but it's really hard. There 
are many commits and nothing obvious stands out.

Things that might make it easier (speculating here):

* add commit hashes to the points in the graphs because Git dates are a bit 
ambiguous: are they author or commit date, what time of day are we talking 
about, what time zone, etc
* higher resolutions for selected periods (requires more build runs). Ideally 
one per commit but that would require vast amounts of time and be very noisy 
(many botched builds), but perhaps one per day?

I'm ashamed to admit that I looked for effects of my own attempts at speeding 
things up, but they were so intermingled with other changes that hard 
conclusions were difficult. (Mattias giveth, Alan taketh away.)

It would be very useful if we could have an automatic (or semi-automatic) daily 
build monitoring performance like this, perhaps even running benchmarks.

Selecting good benchmarks is hard; the elisp-benchmarks in ELPA were made by 
Andrea for his compilation efforts and are nigh-useless for anything else, 
unfortunately. I've written my own suites but again they are only useful for 
what measuring very specific aspects.