Support parallel testing in libgomp, part II [PR66005]

..., and enable if 'flock' is available for serializing execution testing.

Regarding the default of 19 parallel slots, this turned out to be a local
minimum for wall time when testing this on:

    $ uname -srvi
    Linux 4.2.0-42-generic #49~14.04.1-Ubuntu SMP Wed Jun 29 20:22:11 UTC 2016 x86_64
    $ grep '^model name' < /proc/cpuinfo | uniq -c
         32 model name      : Intel(R) Xeon(R) CPU E5-2640 v3 @ 2.60GHz

... in two configurations: case (a) standard configuration, no offloading
configured, case (b) offloading for GCN and nvptx configured but no devices
available.  For both cases, default plus '-m32' variant.

    $ \time make check-target-libgomp RUNTESTFLAGS="--target_board=unix\{,-m32\}"

Case (a), baseline:

    6432.23user 332.38system 47:32.28elapsed 237%CPU (0avgtext+0avgdata 505044maxresident)k
    6382.43user 319.21system 47:06.04elapsed 237%CPU (0avgtext+0avgdata 505172maxresident)k

This is what people have been complaining about, rightly so, in
<https://gcc.gnu.org/PR66005> "libgomp make check time is excessive" and
elsewhere.

Case (a), parallelized:

    -j12 GCC_TEST_PARALLEL_SLOTS=10
    3088.49user 267.74system 6:43.82elapsed 831%CPU (0avgtext+0avgdata 505188maxresident)k
    -j15 GCC_TEST_PARALLEL_SLOTS=15
    3308.08user 294.79system 5:56.04elapsed 1011%CPU (0avgtext+0avgdata 505360maxresident)k
    -j17 GCC_TEST_PARALLEL_SLOTS=17
    3539.93user 298.99system 5:27.86elapsed 1170%CPU (0avgtext+0avgdata 505112maxresident)k
    -j18 GCC_TEST_PARALLEL_SLOTS=18
    3697.50user 317.18system 5:14.63elapsed 1275%CPU (0avgtext+0avgdata 505360maxresident)k
    -j19 GCC_TEST_PARALLEL_SLOTS=19
    3765.94user 324.27system 5:13.22elapsed 1305%CPU (0avgtext+0avgdata 505128maxresident)k
    -j20 GCC_TEST_PARALLEL_SLOTS=20
    3684.66user 312.32system 5:15.26elapsed 1267%CPU (0avgtext+0avgdata 505100maxresident)k
    -j23 GCC_TEST_PARALLEL_SLOTS=23
    4040.59user 347.10system 5:29.12elapsed 1333%CPU (0avgtext+0avgdata 505200maxresident)k
    -j26 GCC_TEST_PARALLEL_SLOTS=26
    3973.24user 377.96system 5:24.70elapsed 1340%CPU (0avgtext+0avgdata 505160maxresident)k
    -j32 GCC_TEST_PARALLEL_SLOTS=32
    4004.42user 346.10system 5:16.11elapsed 1376%CPU (0avgtext+0avgdata 505160maxresident)k

Yay!

Case (b), baseline; 2+ h:

    7227.58user 700.54system 2:14:33elapsed 98%CPU (0avgtext+0avgdata 994264maxresident)k

Case (b), parallelized:

    -j12 GCC_TEST_PARALLEL_SLOTS=10
    7377.46user 777.52system 16:06.63elapsed 843%CPU (0avgtext+0avgdata 994344maxresident)k
    -j15 GCC_TEST_PARALLEL_SLOTS=15
    8019.18user 721.42system 12:13.56elapsed 1191%CPU (0avgtext+0avgdata 994228maxresident)k
    -j17 GCC_TEST_PARALLEL_SLOTS=17
    8530.11user 716.95system 10:45.92elapsed 1431%CPU (0avgtext+0avgdata 994176maxresident)k
    -j18 GCC_TEST_PARALLEL_SLOTS=18
    8776.79user 645.89system 10:27.20elapsed 1502%CPU (0avgtext+0avgdata 994248maxresident)k
    -j19 GCC_TEST_PARALLEL_SLOTS=19
    9332.37user 641.76system 10:15.09elapsed 1621%CPU (0avgtext+0avgdata 994260maxresident)k
    -j20 GCC_TEST_PARALLEL_SLOTS=20
    9609.54user 789.88system 10:26.94elapsed 1658%CPU (0avgtext+0avgdata 994284maxresident)k
    -j23 GCC_TEST_PARALLEL_SLOTS=23
    10362.40user 911.14system 10:44.47elapsed 1749%CPU (0avgtext+0avgdata 994208maxresident)k
    -j26 GCC_TEST_PARALLEL_SLOTS=26
    11159.44user 850.99system 11:09.25elapsed 1794%CPU (0avgtext+0avgdata 994256maxresident)k
    -j32 GCC_TEST_PARALLEL_SLOTS=32
    11453.50user 939.52system 11:00.38elapsed 1876%CPU (0avgtext+0avgdata 994240maxresident)k

On my Dell Precision 7530 laptop:

    $ uname -srvi
    Linux 5.15.0-71-generic #78-Ubuntu SMP Tue Apr 18 09:00:29 UTC 2023 x86_64
    $ grep '^model name' < /proc/cpuinfo | uniq -c
         12 model name      : Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz
    $ nvidia-smi -L
    GPU 0: Quadro P1000 (UUID: GPU-e043973b-b52a-d02b-c066-a8fdbf64e8ea)

... in two configurations: case (c) standard configuration, no offloading
configured, case (d) offloading for nvptx configured and device available.
For both cases, only default variant, no '-m32'.

    $ \time make check-target-libgomp

Case (c), baseline; roughly half of case (a) (just one variant):

    1180.98user 110.80system 19:36.40elapsed 109%CPU (0avgtext+0avgdata 505148maxresident)k
    1133.22user 111.08system 19:35.75elapsed 105%CPU (0avgtext+0avgdata 505212maxresident)k

Case (c), parallelized:

    -j12 GCC_TEST_PARALLEL_SLOTS=2
    1143.83user 110.76system 10:20.46elapsed 202%CPU (0avgtext+0avgdata 505216maxresident)k
    -j12 GCC_TEST_PARALLEL_SLOTS=6
    1737.08user 143.94system 4:59.48elapsed 628%CPU (0avgtext+0avgdata 505200maxresident)k
    1730.31user 143.02system 4:58.75elapsed 627%CPU (0avgtext+0avgdata 505152maxresident)k
    -j12 GCC_TEST_PARALLEL_SLOTS=8
    2192.63user 169.34system 4:52.96elapsed 806%CPU (0avgtext+0avgdata 505216maxresident)k
    2219.04user 167.67system 4:53.19elapsed 814%CPU (0avgtext+0avgdata 505152maxresident)k
    -j12 GCC_TEST_PARALLEL_SLOTS=10
    2463.93user 184.98system 4:48.39elapsed 918%CPU (0avgtext+0avgdata 505200maxresident)k
    2455.62user 183.68system 4:47.40elapsed 918%CPU (0avgtext+0avgdata 505216maxresident)k
    -j12 GCC_TEST_PARALLEL_SLOTS=12
    2591.04user 192.64system 4:44.98elapsed 976%CPU (0avgtext+0avgdata 505216maxresident)k
    2581.23user 195.21system 4:47.51elapsed 965%CPU (0avgtext+0avgdata 505212maxresident)k
    -j20 GCC_TEST_PARALLEL_SLOTS=20 [oversubscribe]
    2613.18user 199.51system 4:44.06elapsed 990%CPU (0avgtext+0avgdata 505216maxresident)k

Case (d), baseline (compared to case (b): only nvptx offloading compilation,
but also nvptx offloading execution); ~1 h:

    2841.93user 653.68system 1:02:26elapsed 93%CPU (0avgtext+0avgdata 909792maxresident)k
    2842.03user 654.39system 1:02:24elapsed 93%CPU (0avgtext+0avgdata 909880maxresident)k

Case (d), parallelized:

    -j12 GCC_TEST_PARALLEL_SLOTS=2
    2856.39user 606.87system 33:58.64elapsed 169%CPU (0avgtext+0avgdata 909948maxresident)k
    -j12 GCC_TEST_PARALLEL_SLOTS=6
    3444.90user 666.86system 18:37.57elapsed 367%CPU (0avgtext+0avgdata 909856maxresident)k
    3462.13user 667.13system 18:36.87elapsed 369%CPU (0avgtext+0avgdata 909872maxresident)k
    -j12 GCC_TEST_PARALLEL_SLOTS=8
    3929.74user 716.22system 18:02.36elapsed 429%CPU (0avgtext+0avgdata 909832maxresident)k
    -j12 GCC_TEST_PARALLEL_SLOTS=10
    4152.84user 736.16system 17:43.05elapsed 459%CPU (0avgtext+0avgdata 909872maxresident)k
    -j12 GCC_TEST_PARALLEL_SLOTS=12
    4209.60user 749.00system 17:35.20elapsed 469%CPU (0avgtext+0avgdata 909840maxresident)k
    -j20 GCC_TEST_PARALLEL_SLOTS=20 [oversubscribe]
    4255.54user 756.78system 17:29.06elapsed 477%CPU (0avgtext+0avgdata 909868maxresident)k

Worth noting is that with nvptx offloading, there is one execution test case
that times out ('libgomp.fortran/reverse-offload-5.f90').  This effectively
stalls progress for almost 5 min: quickly other executions test cases queue up
on the lock for all parallel slots.  That's working as expected; just noting
this as it accordingly does skew the wall time numbers.

	PR testsuite/66005
	libgomp/
	* configure.ac: Look for 'flock'.
	* testsuite/Makefile.am (gcc_test_parallel_slots): Enable parallel testing.
	* testsuite/config/default.exp: Don't 'load_lib "standard.exp"' here...
	* testsuite/lib/libgomp.exp: ... but here, instead.
	(libgomp_load): Override for parallel testing.
	* testsuite/libgomp-site-extra.exp.in (FLOCK): Set.
	* configure: Regenerate.
	* Makefile.in: Regenerate.
	* testsuite/Makefile.in: Regenerate.

(cherry picked from commit 6c3b30ef9e0578509bdaf59c13da4a212fe6c2ba)

1 files changed, 46 insertions, 2 deletions

diff --git a/libgomp/configure b/libgomp/configure
index 718a76b..0430da74 100755
--- a/libgomp/configure
+++ b/libgomp/configure
@@ -656,6 +656,7 @@ tmake_file
 XLDFLAGS
 XCFLAGS
 config_path
+FLOCK
 CPU_COUNT
 LIBGOMP_BUILD_VERSIONED_SHLIB_SUN_FALSE
 LIBGOMP_BUILD_VERSIONED_SHLIB_SUN_TRUE
@@ -11421,7 +11422,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11424 "configure"
+#line 11425 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11527,7 +11528,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11530 "configure"
+#line 11531 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -16643,6 +16644,49 @@ $as_echo "unable to detect (assuming 1)" >&6; }
 fi
 
 
+for ac_prog in flock
+do
+  # Extract the first word of "$ac_prog", so it can be a program name with args.
+set dummy $ac_prog; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_prog_FLOCK+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$FLOCK"; then
+  ac_cv_prog_FLOCK="$FLOCK" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_prog_FLOCK="$ac_prog"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+FLOCK=$ac_cv_prog_FLOCK
+if test -n "$FLOCK"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $FLOCK" >&5
+$as_echo "$FLOCK" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+  test -n "$FLOCK" && break
+done
+
+
 # Get target configury.
 . ${srcdir}/configure.tgt
 CFLAGS="$save_CFLAGS $XCFLAGS"