[bug#60808] [PATCH 2/2] tests: reuse am_cv_filesystem_timestamp_resolution

[Mike Frysinger]

Rather than assume such coarse delays, re-use existing logic for
probing the current filesystem resolution.  This speeds up the
testsuite significantly.  On my system, it speeds -j1 up quite a
lot -- by ~30%.  While I didn't gather many samples to produce a
statistically significant distribution, my runs seem to be fairly
consistent with the values below with deviations of <1 minute.

$ time make -j1
    Before                After
real  33m17.182s      real  23m33.557s
user  12m12.145s      user  12m12.763s
sys   1m52.308s       sys   1m52.853s

$ time make -j32
    Before                After
real  1m35.874s       real  1m4.908s
user  14m24.664s      user  15m58.663s
sys   2m9.297s        sys   2m27.393s

* configure.ac: Set test delays to am_cv_filesystem_timestamp_resolution.
---
 configure.ac | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/configure.ac b/configure.ac
index dcf2d95566a0..d3a67d5ffec9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -172,15 +172,7 @@ result=no
 test "x$am_cv_prog_ln" = xln && result=yes
 AC_MSG_RESULT([$result])
 
-# The amount we should wait after modifying files depends on the platform.
-# On Windows '95, '98 and ME, files modifications have 2-seconds
-# granularity and can be up to 3 seconds in the future w.r.t. the
-# system clock.  When it is important to ensure one file is older
-# than another we wait at least 5 seconds between creations.
-case $build in
-  *-pc-msdosdjgpp) MODIFICATION_DELAY=5;;
-  *)               MODIFICATION_DELAY=2;;
-esac
+MODIFICATION_DELAY=$am_cv_filesystem_timestamp_resolution
 AC_SUBST([MODIFICATION_DELAY])
 
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2.39.0