These ten hold up the wall clock on their own. Their configure stages
run while nothing else does, because the tools build in dependency
order. Measured over a full build, cold cache against warm:
sed 21.68 s -> 1.22 s
m4 21.48 s -> 1.22 s
findutils 19.47 s -> 1.56 s
tar 17.75 s -> 1.47 s
cpio 14.28 s -> 1.26 s
bison 12.81 s -> 1.29 s
patch 12.16 s -> 1.31 s
elfutils 26.58 s -> 15.47 s
Each of the ten configures the same way with a warm cache as it does
without one. The check runs configure three times, without a cache, with
a cold cache and with a warm cache, and compares every file that
configure generates between the first and the last. ncurses fails that
check; these do not.
The only difference left is ac_ct_AR and ac_ct_RANLIB, which a cold run
fills through the fallback path of AC_CHECK_TOOL and a warm run leaves
empty. AR and RANLIB are correct in both, and no generated Makefile
reads the ac_ct_ form.
tools/cmake keeps its 33 s, the longest configure stage in the build. It
bootstraps with its own script rather than autoconf, so this does not
reach it.
Signed-off-by: John Crispin <john@phrozen.org>
John Crispin
cd322612cc