Maintain runtime of each benchmark at ~10 seconds

The idea to run benchmarks for a constant number of iterations is
problematic.  While the benchmarks may run for 10 seconds on x86_64,
they could run for about 30 seconds on powerpc and worse, over 3
minutes on arm.  Besides that, adding a new benchmark is cumbersome
since one needs to find out the number of iterations needed for a
sufficient runtime.

A better idea would be to run each benchmark for a specific amount of
time.  This patch does just that.  The run time defaults to 10 seconds
and it is configurable at command line:

  make BENCH_DURATION=5 bench

1 files changed, 11 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index a56bf73405..07ec4d05e2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2013-04-30  Siddhesh Poyarekar  <siddhesh@redhat.com>
+
+	* benchtests/Makefile: Remove *-ITER.  Define BENCH_DURATION
+	in CPPFLAGS.
+	($(objpfx)bench-%.c): Remove *-ITER.
+	* benchtests/bench-modf.c: Remove definition of ITER.
+	* benchtests/bench-skeleton.c (TIMESPEC_AFTER): New macro.
+	(main): Loop for DURATION seconds instead of fixed number of
+	iterations.
+	* scripts/bench.pl: Don't expect iterations in parameters.
+
 2013-04-29  Roland McGrath  <roland@hack.frob.com>
 
 	* io/fchdir.c (__fchdir): Renamed from fchdir.