* cfg.mk: Set XZ_OPT = -7e (determined empirically).
The compressed tarball size is identical to the default settings (-9e),
but using -9e would force every decompression process to use 48 MiB
more memory.
---
cfg.mk | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/cfg.mk b/cfg.mk
index 1ac49f0..aa47618 100644
--- a/cfg.mk
+++ b/cfg.mk
@@ -34,6 +34,33 @@ exclude_file_name_regexp--sc_space_tab = \
# any case we don't use help2man at all.
local-checks-to-skip += sc_two_space_separator_in_usage
+# Comparing tarball sizes compressed using different xz presets, we see that
+# an -7e-compressed tarball has the same size as the -9e-compressed one.
+# Using -7e is preferred, since that lets the decompression process use less
+# memory (19MiB rather than 67MiB).
+# $ pkg=x; out=x.out; \
+# printf "%3s %8s %6s %s\n" OPT PKGSIZE RESMEM TIME; \
+# for i in {5..9}{e,}; do \
+# xz -$i < findutils-4.7.0-git.tar > $pkg; \
+# s=$(wc -c < $pkg); \
+# env time -v xz -d - < $pkg >/dev/null 2> $out; \
+# m=$(sed -n '/Maximum resident set size/{s/^.*: //;p;q}' < $out); \
+# t=$(sed -n '/User time/{s/^.*: //;p;q}' < $out); \
+# printf "%3s %8d %6d %s\n" "$i" "$s" "$m" "$t"; \
+# done | sort -k2,2nr
+#OPT PKGSIZE RESMEM TIME
+# 5 1994080 10484 0.12
+# 6 1956672 10564 0.11
+# 5e 1935660 10456 0.11
+# 6e 1930628 10396 0.11
+# 8 1881520 34880 0.11
+# 9 1881520 67732 0.12
+# 7 1881496 18564 0.11
+# 7e 1855268 18584 0.11
+# 8e 1855268 35016 0.11
+# 9e 1855268 67844 0.11
+export XZ_OPT = -7e
+
# Some test inputs/outputs have trailing blanks.
exclude_file_name_regexp--sc_trailing_blank = \
^COPYING|(po/.*\.po)|(find/testsuite/(test_escapechars\.golden|find.gnu/printf\.xo))|(xargs/testsuite/(inputs/.*\.xi|xargs\.(gnu|posix|sysv)/.*\.(x[oe])))$$
--
2.1.4
