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[bug#49421] [PATCH] profiles: Optimise 'fonts-dir-file'.
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From: |
Maxime Devos |
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Subject: |
[bug#49421] [PATCH] profiles: Optimise 'fonts-dir-file'. |
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Date: |
Thu, 15 Jul 2021 18:28:16 +0200 |
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User-agent: |
Evolution 3.34.2 |
Ludovic Courtès schreef op wo 07-07-2021 om 18:52 [+0200]:
> Hi,
>
> Maxime Devos <maximedevos@telenet.be> skribis:
>
> > These two patches should speed up profile generation
> > by optimising the 'fonts-dir-file' hook. The first patch
> > is the most important; from the commit message:
> >
> > ‘Only let the build G-exp refer to inputs that might actually
> > have fonts. That way, if the list of fonts in the manifest
> > didn't change and the new manifest is built, the font files
> > will not be rebuilt.’
> >
> > The second patch doesn't bring much.
> >
> > To test, you can test whether things like ...
> >
> > $ ./pre-inst-env guix environment --ad-hoc --pure lagrange -- lagrange
> >
> > still work (lagrange is a graphical application using fonts).
> > Not sure what a good ‘benchmark’ would be.
> >
> > Unfortunately, this does not help with the "guix package -i" case,
> > as in that case, the code doesn't have access to all the package objects,
> > and will have to satisfy itself with the store paths, in which case the
> > profile code pessimistically assumes the store item has fonts ...
> >
> > I suppose this restriction could be lifted if/when the gs-fonts package
> > is renamed to font-ghostscript or something like that ...
>
> Do you know what’s taking time in the ‘fonts-dir-file’ hook?
> (On my x86_64 laptop with SSD, it runs in 4.4s on a cold cache for a
> profile containing 14 font packages, and in 1.2s on a warm cache.)
I noticed ‘building fonts directories’ was taking long (9 minutes or so,
when using "guix package -r two packages that don't have fonts"),
so I took the opportunity to "strace" the process, though I was a little late.
Some statistics:
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
27,14 1,676551 117 14297 rename
19,60 1,211012 13 90829 8 lstat
18,34 1,133182 63 17787 15 statx
11,80 0,729185 51 14297 link
6,65 0,411065 68510 6 wait4
5,08 0,313632 10 28651 chmod
3,66 0,226258 14 15114 readlink
2,18 0,134913 8 15193 utimensat
1,78 0,110257 32 3431 rmdir
0,91 0,056504 7 7370 getdents64
0,82 0,050817 3 14295 getpid
0,47 0,029074 7 3736 openat
0,46 0,028547 8 3479 3428 unlink
0,36 0,021940 5 3747 close
0,26 0,016355 4 3704 fstat
0,16 0,009752 10 898 lchown
0,12 0,007242 4 1800 geteuid
0,07 0,004203 62 67 read
0,06 0,003512 3 900 getegid
0,03 0,001959 326 6 clone
0,02 0,001133 18 62 write
0,01 0,000488 3 127 1 fcntl
0,01 0,000451 3 136 lseek
0,00 0,000197 14 14 mkdir
0,00 0,000065 13 5 select
0,00 0,000045 5 8 chown
0,00 0,000044 7 6 brk
0,00 0,000027 13 2 munmap
0,00 0,000023 11 2 pipe
0,00 0,000013 6 2 stat
0,00 0,000007 7 1 futex
0,00 0,000004 2 2 getuid
0,00 0,000000 0 1 rt_sigreturn
------ ----------- ----------- --------- --------- ----------------
100,00 6,178457 25 239975 3452 total
And a part of the log:
<start of log>
lstat("/gnu/store/.links/[...]2i", {st_mode=S_IFLNK|0777, st_size=124, ...}) = 0
lstat("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283",
{st_mode=S_IFDIR|0555, st_size=4112, ...>
chmod("/gnu/store/[..]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283",
040755) = 0
getpid() = 26371
link("/gnu/store/.links/[..]2i", "/gnu/store/.tmp-link-26371-632297102") = 0
rename("/gnu/store/.tmp-link-26371-632297102",
"/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283/2>
lstat("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283",
{st_mode=S_IFDIR|0755, st_size=4112, ...>
chmod("/gnu/store/[...]-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283",
040555) = 0
utimensat(AT_FDCWD,
"/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283",
[{tv_sec=1626363034, tv_ns>
lstat("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283/2223.png",
{st_mode=S_IFLNK|0777, st_size=>
lstat("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283/2223.png",
{st_mode=S_IFLNK|0777, st_size=>
lstat("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283/2223.png",
{st_mode=S_IFLNK|0777, st_size=>
readlink("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283/2223.png",
"/gnu/store/bf582s56ldb3y34p>
statx(AT_FDCWD, "/gnu/store/.links/[...]v3",
AT_STATX_SYNC_AS_STAT|AT_SYMLINK_NOFOLLOW, 0, {stx_mask=STATX_ALL|>
lstat("/gnu/store/.links/[...]v3", {st_mode=S_IFLNK|0777, st_size=124, ...}) = 0
lstat("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283",
{st_mode=S_IFDIR|0555, st_size=4112, ...>
chmod("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283",
040755) = 0
getpid() = 26371
link("/gnu/store/.links/[...]v3", "/gnu/store/.tmp-link-26371-114005693") = 0
rename("/gnu/store/.tmp-link-26371-114005693",
"/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283/2>
lstat("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283",
{st_mode=S_IFDIR|0755, st_size=4112, ...>
chmod("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283",
040555) = 0
utimensat(AT_FDCWD,
"/gnu/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283",
[{tv_sec=1626363034, tv_ns>
lstat("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283/22CC.png",
{st_mode=S_IFLNK|0777, st_size=>
lstat("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283/22CC.png",
{st_mode=S_IFLNK|0777, st_size=>
lstat("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283/22CC.png",
{st_mode=S_IFLNK|0777, st_size=>
readlink("/gnu/store/h6681qq9s5kqjvdzkhqhddqbjj3q48nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283/22CC.png",
"/gnu/store/bf582s56ldb3y34p>
statx(AT_FDCWD, "/gnu/store/.links/[...]my",
AT_STATX_SYNC_AS_STAT|AT_SYMLINK_NOFOLLOW, 0, {stx_mask=STATX_ALL|>
lstat("/gnu/store/.links/[...]my", {st_mode=S_IFLNK|0777, st_size=124, ...}) = 0
lstat("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283",
{st_mode=S_IFDIR|0555, st_size=4112, ...>
chmod("/gnu/store/[...]nm-fonts-dir/share/fonts/mathjax/HTML-CSS/TeX/png/AMS/Regular/283",
040755) = 0
getpid() = 26371
<end of log>
It seems like ‘duplication’ is taking a lot of time!
(See nix/libstore/optimise-store.cc and (guix store deduplication).)
> IIUC, the hook completes almost instantaneously when creating a profile
> without fonts because (null? fonts-dirs) is true.
>
> In other cases, one option to speed things up (and possibly remove the
> hook’s dependency on mkfontdir) would be to create ‘fonts.dir’ and
> ‘fonts.scale’ in a build phase of each font package, *provided* there’s
> a cheap way to assemble several such files, such as mere concatenation.
> That way, the profile hook would only need to assemble these files as
> opposed to traversing all the font files.
Looking at ~/.guix-profile/share/fonts/truetype/fonts.dir,
it seems to be simply a list of entries lke
DejaVuSans-Bold.ttf -misc-dejavu sans-bold-r-normal--0-0-0-0-p-0-koi8-ru
with additionally as first line the number of fonts. It appears to be
sorted by font file name (DejaVuSans-Bold.ttf) though, though that only
seems to be to not depend on file system ordering. Not quite _mere_
concatenation, but should be easy enough, I think.
(Likewise for fonts.scaale)
I would need to look at the code of "mkfontscale" and "mkfontdir" to be sure
though.
> Given that ‘fonts.dir’ and ‘fonts.scale’ are mere text files with one
> line per font, this approach looks doable.
>
> WDYT?
That seems a good idea, reducing the amount of 'stat'ing, 'readdir'ing,
and 'read'ing (mkfontscale needs to actually read the font files)
which should help on spinning disks (and other disks, but on SSDs it's probably
less noticable).
> > From 4fe1e30e33c01be9fd17cf240732b3351c7b0fa4 Mon Sep 17 00:00:00 2001
> > From: Maxime Devos <maximedevos@telenet.be>
> > Date: Mon, 5 Jul 2021 18:55:31 +0200
> > Subject: [PATCH 1/2] profiles: Optimise 'fonts-dir-file'.
> >
> > Only let the build G-exp refer to inputs that might actually
> > have fonts. That way, if the list of fonts in the manifest
> > didn't change and the new manifest is built, the font files
> > will not be rebuilt.
> >
> > * guix/profiles.scm
> > (fonts-dir-file)[has-fonts?]: New predicate.
> > (fonts-dir-file)[relevant-inputs]: New variable.
> > (fonts-dir-file)[build]: Use 'relevant-inputs' instead of
> > 'manifest-inputs'.
> > * doc/contributing.texi (Fonts): Note the 'fonts-' naming
> > convention is technically important now.
> > * gnu/packages/ghostscript.scm (gs-fonts): Work-around the
> > package name contravening the convention.
>
> To me this approach should be a last resort because it relies on
> conventions and manual annotations, and it’s easy to forget these and
> get incorrect results (we could end up having to deal with reports like
> “I installed font X, why doesn’t in show up in the font list?”).
AFAIK, all font packages in Guix (except gs-fonts) are currently
correctly-named. They aren't going to spontanuously rename theirselves.
So to me, the only potential problem seems to be _new_ font packages
ignoring the conventions. But new packages should always be reviewed and
tested, so such reports don't seem plausible to me.
(Also, the manual annotation would go away once 'gs-fonts' is renamed.
I'll run "echo /gnu/store/*/share/fonts > atchie-fonts" though to see
if there are other packages not following the convention.)
> > + ;; In the upstream 'guix' channel, font packages should
> > + ;; be named font-SOMETHING. But if another channel
> > + ;; names its fonts differently but uses font-build-system,
> > + ;; accepting that seems friendly.
> > + (eq? 'font (build-system-name (package-build-system thing)))
>
> In general ‘build-system-name’ shouldn’t be used; the name is meant to
> be a debugging aid.
I could do (eq? font-build-system (packag-build-system thing)) instead
or drop this clause.
> Thanks,
> Ludo’.
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