[bug#49421] [PATCH] profiles: Optimise 'fonts-dir-file'.

[Ludovic Courtès]

Hello,

Maxime Devos <maximedevos@telenet.be> skribis:

> Ludovic Courtès schreef op vr 16-07-2021 om 18:05 [+0200]:
>> Ouch, that’s way more than what I’m observing.  :-)  Do you have a
>> manifest or package list to reproduce that?  Were those timings on a
>> spinning disk?
>
> It is on a spinning disk.  I attached the output of "guix package 
> --export-manifest".

I isolated ‘fonts-dir.drv’ for that profile and here’s what I get with a
~5yo SSD:

--8<---------------cut here---------------start------------->8---
$ time guix build  /gnu/store/nmr6clkx4n554a0gynr6sb4a43dj6mfa-fonts-dir.drv 
--check
The following profile hook will be built:
   /gnu/store/nmr6clkx4n554a0gynr6sb4a43dj6mfa-fonts-dir.drv
building fonts directory...
successfully built /gnu/store/nmr6clkx4n554a0gynr6sb4a43dj6mfa-fonts-dir.drv
successfully built /gnu/store/nmr6clkx4n554a0gynr6sb4a43dj6mfa-fonts-dir.drv
/gnu/store/fgjmwpgrmp9m83qxvqrs1ghwasjrjxpc-fonts-dir

real    0m24.651s
user    0m2.120s
sys     0m0.164s
$ time guix build  /gnu/store/nmr6clkx4n554a0gynr6sb4a43dj6mfa-fonts-dir.drv 
--check
The following profile hook will be built:
   /gnu/store/nmr6clkx4n554a0gynr6sb4a43dj6mfa-fonts-dir.drv
building fonts directory...
successfully built /gnu/store/nmr6clkx4n554a0gynr6sb4a43dj6mfa-fonts-dir.drv
successfully built /gnu/store/nmr6clkx4n554a0gynr6sb4a43dj6mfa-fonts-dir.drv
/gnu/store/fgjmwpgrmp9m83qxvqrs1ghwasjrjxpc-fonts-dir

real    0m12.025s
user    0m1.924s
sys     0m0.036s
--8<---------------cut here---------------end--------------->8---

That’s fairly significant (it baffles me that it’s still 20x less than
what you see with a spinning disk!).

There are only 327 fonts in there:

--8<---------------cut here---------------start------------->8---
$ wc -l 
/gnu/store/fgjmwpgrmp9m83qxvqrs1ghwasjrjxpc-fonts-dir/share/fonts/truetype/fonts.*
  328 
/gnu/store/fgjmwpgrmp9m83qxvqrs1ghwasjrjxpc-fonts-dir/share/fonts/truetype/fonts.dir
  328 
/gnu/store/fgjmwpgrmp9m83qxvqrs1ghwasjrjxpc-fonts-dir/share/fonts/truetype/fonts.scale
  656 totalo
--8<---------------cut here---------------end--------------->8---

Thanks,
Ludo’.