| Message ID | d2647ed721b9f12b1267427409455e385ffaa12d.1624063731.git.iskarian@mgsn.dev |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [bug#49107,core-updates] gnu: fontconfig: Use (locally) deterministic caching | expand |
| Context | Check | Description |
|---|---|---|
| cbaines/applying patch | fail | View Laminar job |
| cbaines/issue | success | View issue |
Hi, Sarah Morgensen <iskarian@mgsn.dev> skribis: > Make fontconfig use directory contents rather than modification time to > determine cache validity (by pretending that mtime is broken). > > * gnu/packages/patches/fontconfig-cache-ignore-mtime.patch: New file. > * gnu/local.mk (dist_patch_DATA): Register it. > * gnu/packages/fontutils.scm (fontconfig)[source]: Use it. > [arguments]: Unset SOURCE_DATE_EPOCH for tests. > --- > gnu/local.mk | 1 + > gnu/packages/fontutils.scm | 7 ++++++- > .../patches/fontconfig-cache-ignore-mtime.patch | 15 +++++++++++++++ > 3 files changed, 22 insertions(+), 1 deletion(-) > create mode 100644 gnu/packages/patches/fontconfig-cache-ignore-mtime.patch > > Hello Guix, > > This patch attempts to make fontconfig's caching work seamlessly on Guix, > instead of requiring users to manually run `fc-cache -f` after installing or > removing fonts. This addresses <https://issues.guix.gnu.org/18640>. > > Fontconfig usually uses a directory's mtime as its checksum. However, when > fontconfig detects a "broken mtime" filesystem, it will generate a directory > checksum from the directory listing contents. This is slightly slower, as it has > to stat all the files in all font directories. Unconditionally enabling this > mode should get us more regular behavior. Nice, sounds like an improvement! Does Fontconfig stats all these files every time an application starts? Did you compare ‘strace -c some app’ with and without this change, to get an idea of what it costs? > I am not confident this method is fully deterministic; particular filesystem > capabilities may still be an implicit imput in the checksums. This should only > matter when distributing pre-generated caches. > > Fontconfig does honor SOURCE_DATE_EPOCH, but without a reliable mtime, > fontconfig has no way of knowing when to update such a cache. SOURCE_DATE_EPOCH > is now disabled for the tests because they assume working cache invalidation. So tests fail is we leave SOURCE_DATE_EPOCH, right? Thanks for addressing this longstanding issue! (And apologies for the delay… Now’s a good time to get semi-high-level changes like this one in ‘core-updates’.) Ludo’.
Hello, Thanks for taking a look at this. Ludovic Courtès <ludo@gnu.org> writes: >> Fontconfig usually uses a directory's mtime as its checksum. However, when >> fontconfig detects a "broken mtime" filesystem, it will generate a directory >> checksum from the directory listing contents. This is slightly slower, as it has >> to stat all the files in all font directories. Unconditionally enabling this >> mode should get us more regular behavior. > > Nice, sounds like an improvement! > > Does Fontconfig stats all these files every time an application starts? > Did you compare ‘strace -c some app’ with and without this change, to > get an idea of what it costs? I *believe* it does so whenever an application calls FcFontList or such, which is usually on startup. I haven't done tracing with an application that actually uses FcFontList, but I just now ran a naive test, along the lines of: $ fc-cache -rf $ strace -c fc-list The old fc-list: --8<---------------cut here---------------start------------->8--- % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 28.50 0.000226 0 228 142 openat 22.19 0.000176 1 136 26 access 11.10 0.000088 0 133 70 stat 5.93 0.000047 0 86 close 5.55 0.000044 2 22 fstatfs 5.30 0.000042 0 54 37 readlink 4.54 0.000036 4 8 munmap 3.78 0.000030 0 70 mmap 2.65 0.000021 1 20 write 2.52 0.000020 0 104 read 2.52 0.000020 0 40 fstat 1.89 0.000015 1 8 fadvise64 1.77 0.000014 1 10 getpid 0.88 0.000007 0 10 brk 0.63 0.000005 0 35 getrandom 0.25 0.000002 2 1 1 ioctl 0.00 0.000000 0 15 mprotect 0.00 0.000000 0 2 rt_sigaction 0.00 0.000000 0 1 rt_sigprocmask 0.00 0.000000 0 1 execve 0.00 0.000000 0 1 arch_prctl 0.00 0.000000 0 1 futex 0.00 0.000000 0 4 getdents64 0.00 0.000000 0 1 set_tid_address 0.00 0.000000 0 1 set_robust_list 0.00 0.000000 0 1 prlimit64 ------ ----------- ----------- --------- --------- ---------------- 100.00 0.000793 0 993 276 total --8<---------------cut here---------------end--------------->8--- And the patched fc-list: --8<---------------cut here---------------start------------->8--- % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 17.19 0.000125 0 126 11 access 14.44 0.000105 0 126 52 openat 12.24 0.000089 1 55 mmap 10.32 0.000075 0 99 read 8.67 0.000063 4 15 mprotect 8.25 0.000060 0 94 6 newfstatat 5.50 0.000040 0 74 close 5.23 0.000038 0 58 40 readlink 4.68 0.000034 34 1 set_tid_address 3.30 0.000024 0 38 getrandom 3.16 0.000023 1 13 pread64 1.65 0.000012 0 26 getdents64 1.51 0.000011 1 9 brk 1.10 0.000008 4 2 rt_sigaction 0.83 0.000006 0 9 munmap 0.55 0.000004 4 1 rt_sigprocmask 0.55 0.000004 4 1 prlimit64 0.41 0.000003 3 1 arch_prctl 0.41 0.000003 3 1 set_robust_list 0.00 0.000000 0 20 write 0.00 0.000000 0 1 1 ioctl 0.00 0.000000 0 1 execve 0.00 0.000000 0 1 sysinfo 0.00 0.000000 0 11 fstatfs 0.00 0.000000 0 8 fadvise64 ------ ----------- ----------- --------- --------- ---------------- 100.00 0.000727 0 791 110 total --8<---------------cut here---------------end--------------->8--- Now that is unexpected! There are actually less stats and opens. I'm stumped! My profile has about 20 font packages (about 450 actual files) installed. For reference, for both versions, `fc-cache -rf` yields about 3700 stats; and `fc-cache` yeilds about 300... I suppose I should be more careful about speaking from theory! > >> I am not confident this method is fully deterministic; particular filesystem >> capabilities may still be an implicit imput in the checksums. This should only >> matter when distributing pre-generated caches. >> >> Fontconfig does honor SOURCE_DATE_EPOCH, but without a reliable mtime, >> fontconfig has no way of knowing when to update such a cache. SOURCE_DATE_EPOCH >> is now disabled for the tests because they assume working cache invalidation. > > So tests fail is we leave SOURCE_DATE_EPOCH, right? Correct. > Thanks for addressing this longstanding issue! (And apologies for the > delay… Now’s a good time to get semi-high-level changes like this one > in ‘core-updates’.) I still wish we could address it "properly" by generating a cache at profile generation time... but it looks like fontconfig embeds the full paths of fonts in the cache (including username, since fonts are under ~/.guix-profile), so I doubt such a cache would work. I plan to try it eventually anyway (or perhaps someone else will), but in the meantime, this looks like the 80% solution. -- Sarah
Hi, Sarah Morgensen <iskarian@mgsn.dev> skribis: > Ludovic Courtès <ludo@gnu.org> writes: [...] >> Does Fontconfig stats all these files every time an application starts? >> Did you compare ‘strace -c some app’ with and without this change, to >> get an idea of what it costs? > > I *believe* it does so whenever an application calls FcFontList or such, > which is usually on startup. I haven't done tracing with an application > that actually uses FcFontList, but I just now ran a naive test, along > the lines of: > > $ fc-cache -rf > $ strace -c fc-list > > The old fc-list: > > % time seconds usecs/call calls errors syscall > ------ ----------- ----------- --------- --------- ---------------- > 28.50 0.000226 0 228 142 openat > 22.19 0.000176 1 136 26 access > 11.10 0.000088 0 133 70 stat > 5.93 0.000047 0 86 close > 5.55 0.000044 2 22 fstatfs > 5.30 0.000042 0 54 37 readlink > 4.54 0.000036 4 8 munmap > 3.78 0.000030 0 70 mmap > 2.65 0.000021 1 20 write > 2.52 0.000020 0 104 read > 2.52 0.000020 0 40 fstat > 1.89 0.000015 1 8 fadvise64 > 1.77 0.000014 1 10 getpid > 0.88 0.000007 0 10 brk > 0.63 0.000005 0 35 getrandom > 0.25 0.000002 2 1 1 ioctl > 0.00 0.000000 0 15 mprotect > 0.00 0.000000 0 2 rt_sigaction > 0.00 0.000000 0 1 rt_sigprocmask > 0.00 0.000000 0 1 execve > 0.00 0.000000 0 1 arch_prctl > 0.00 0.000000 0 1 futex > 0.00 0.000000 0 4 getdents64 > 0.00 0.000000 0 1 set_tid_address > 0.00 0.000000 0 1 set_robust_list > 0.00 0.000000 0 1 prlimit64 > ------ ----------- ----------- --------- --------- ---------------- > 100.00 0.000793 0 993 276 total > > > And the patched fc-list: > > % time seconds usecs/call calls errors syscall > ------ ----------- ----------- --------- --------- ---------------- > 17.19 0.000125 0 126 11 access > 14.44 0.000105 0 126 52 openat > 12.24 0.000089 1 55 mmap > 10.32 0.000075 0 99 read > 8.67 0.000063 4 15 mprotect > 8.25 0.000060 0 94 6 newfstatat > 5.50 0.000040 0 74 close > 5.23 0.000038 0 58 40 readlink > 4.68 0.000034 34 1 set_tid_address > 3.30 0.000024 0 38 getrandom > 3.16 0.000023 1 13 pread64 > 1.65 0.000012 0 26 getdents64 > 1.51 0.000011 1 9 brk > 1.10 0.000008 4 2 rt_sigaction > 0.83 0.000006 0 9 munmap > 0.55 0.000004 4 1 rt_sigprocmask > 0.55 0.000004 4 1 prlimit64 > 0.41 0.000003 3 1 arch_prctl > 0.41 0.000003 3 1 set_robust_list > 0.00 0.000000 0 20 write > 0.00 0.000000 0 1 1 ioctl > 0.00 0.000000 0 1 execve > 0.00 0.000000 0 1 sysinfo > 0.00 0.000000 0 11 fstatfs > 0.00 0.000000 0 8 fadvise64 > ------ ----------- ----------- --------- --------- ---------------- > 100.00 0.000727 0 791 110 total > > Now that is unexpected! There are actually less stats and opens. I'm > stumped! My profile has about 20 font packages (about 450 actual files) > installed. For reference, for both versions, `fc-cache -rf` yields about > 3700 stats; and `fc-cache` yeilds about 300... Well, even better. :-) I went ahead and applied the patch. ‘fontconfig-minimal’ builds fine; ‘fonconfig’ (with documentation) fails to build its PDF documentation, but that’s not related to this change. > I still wish we could address it "properly" by generating a cache at > profile generation time... but it looks like fontconfig embeds the full > paths of fonts in the cache (including username, since fonts are under > ~/.guix-profile), so I doubt such a cache would work. I plan to try it > eventually anyway (or perhaps someone else will), but in the meantime, > this looks like the 80% solution. Yeah. It could be that each font package could contain its own cache, and the profile hook would just assemble all these caches (provided the file format makes it possible without too much of a headache). Thanks! Ludo’.
diff --git a/gnu/local.mk b/gnu/local.mk index c57e587e84..1d26c9e7c7 100644 --- a/gnu/local.mk +++ b/gnu/local.mk @@ -1012,6 +1012,7 @@ dist_patch_DATA = \ %D%/packages/patches/fifo-map-remove-catch.hpp.patch \ %D%/packages/patches/findutils-localstatedir.patch \ %D%/packages/patches/flann-cmake-3.11.patch \ + %D%/packages/patches/fontconfig-cache-ignore-mtime.patch \ %D%/packages/patches/foobillard++-pkg-config.patch \ %D%/packages/patches/foomatic-filters-CVE-2015-8327.patch \ %D%/packages/patches/foomatic-filters-CVE-2015-8560.patch \ diff --git a/gnu/packages/fontutils.scm b/gnu/packages/fontutils.scm index dbce5beba8..0ee51a792e 100644 --- a/gnu/packages/fontutils.scm +++ b/gnu/packages/fontutils.scm @@ -14,6 +14,7 @@ ;;; Copyright © 2020 Nicolas Goaziou <mail@nicolasgoaziou.fr> ;;; Copyright © 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com> ;;; Copyright © 2020, 2021 Nicolas Goaziou <mail@nicolasgoaziou.fr> +;;; Copyright © 2021 Sarah Morgensen <iskarian@mgsn.dev> ;;; ;;; This file is part of GNU Guix. ;;; @@ -331,7 +332,8 @@ Font Format (WOFF).") "https://www.freedesktop.org/software/" "fontconfig/release/fontconfig-" version ".tar.xz")) (sha256 (base32 - "1850q4k80yxma5g3yxkvyv8i5a3xqzswwml8gjy3jmywx8qqd5pa")))) + "1850q4k80yxma5g3yxkvyv8i5a3xqzswwml8gjy3jmywx8qqd5pa")) + (patches (search-patches "fontconfig-cache-ignore-mtime.patch")))) (build-system gnu-build-system) ;; In Requires or Requires.private of fontconfig.pc. (propagated-inputs `(("expat" ,expat) @@ -362,6 +364,9 @@ Font Format (WOFF).") (modify-phases %standard-phases (add-before 'check 'skip-problematic-tests (lambda _ + ;; SOURCE_DATE_EPOCH doesn't make sense when ignoring mtime + (unsetenv "SOURCE_DATE_EPOCH") + (substitute* "test/run-test.sh" ;; The crbug1004254 test attempts to fetch fonts from the ;; network. diff --git a/gnu/packages/patches/fontconfig-cache-ignore-mtime.patch b/gnu/packages/patches/fontconfig-cache-ignore-mtime.patch new file mode 100644 index 0000000000..b6e942ee10 --- /dev/null +++ b/gnu/packages/patches/fontconfig-cache-ignore-mtime.patch @@ -0,0 +1,15 @@ +Pretend that stat's mtime is broken, so that the fontconfig cache does not +depend upon modification time to determine if a cache is stale. + +diff --git a/src/fcstat.c b/src/fcstat.c +index 5a2bd7c..d603a96 100644 +--- a/src/fcstat.c ++++ b/src/fcstat.c +@@ -431,6 +431,7 @@ FcIsFsMmapSafe (int fd) + FcBool + FcIsFsMtimeBroken (const FcChar8 *dir) + { ++ return FcTrue; + int fd = FcOpen ((const char *) dir, O_RDONLY); + + if (fd != -1)