[PATCH v2 6/6] Makerules: add 'make check-parallel' to run tests without serialization

[Adhemerval Zanella]

The default 'make check' serializes the timing-sensitive test runs: the
threading (nptl, or htl on Hurd) and realtime (rt) subdirectories run
with .NOTPARALLEL and are ordered after the rest of the test run, so they
are not perturbed by competing machine load.

Add a check-parallel (and xcheck-parallel) variant for when that is not
wanted -- an idle machine, or a run where the extra throughput is worth
the risk of flakiness in the timing-sensitive tests.

A new serialize-tests flag (default yes, defined in Makeconfig) gates both
the per-subdirectory .NOTPARALLEL and the top-level run-time ordering;
check-parallel just runs the suite with serialize-tests=no, so every test
program builds and runs at full concurrency in a single pass.

'make check' and its default behavior are unchanged.
---
 Makeconfig    |  8 ++++++++
 Makefile      |  3 +++
 Makerules     | 13 +++++++++++++
 htl/Makefile  |  5 +++--
 nptl/Makefile |  5 +++--
 rt/Makefile   |  5 +++--
 6 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/Makeconfig b/Makeconfig
index 8fe7217dd7c..6cd590cf216 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -782,6 +782,14 @@ run-built-tests = yes
 endif
 endif
 
+# Whether the timing-sensitive test runs are serialized: each is run with
+# .NOTPARALLEL and, at the top level, ordered after the rest of the test run.
+# This is the default; 'make check-parallel' clears it to run every test
+# concurrently.
+ifndef serialize-tests
+serialize-tests = yes
+endif
+
 # Whether to build the static math tests
 ifndef build-math-static-tests
 build-math-static-tests = no
diff --git a/Makefile b/Makefile
index 5f2293dfd7d..a38f11facf6 100644
--- a/Makefile
+++ b/Makefile
@@ -594,7 +594,9 @@ $(objpfx)testroot.pristine/install.stamp: | others
 # 'make subdir/tests' is left alone.  And it only orders the test run
 # (run-built-tests=yes); the "build the tests" pass (run-built-tests=no)
 # is left fully parallel, so every test program still builds concurrently.
+# serialize-tests=no ('make check-parallel') drops the ordering entirely.
 ifeq ($(run-built-tests),yes)
+ifeq (yes,$(serialize-tests))
 ifneq (,$(filter tests xtests check xcheck,$(MAKECMDGOALS)))
 +late-test-subdirs := $(filter nptl htl,$(subdirs)) $(filter rt,$(subdirs))
 +test-run-prev := \
@@ -604,6 +606,7 @@ $(foreach d,$(+late-test-subdirs),\
   $(eval +test-run-prev += $(d)/tests))
 endif
 endif
+endif
 
 ifeq (yes,$(build-shared))
 # The top-level libc.so and linkobj/libc_pic.a rules list these
diff --git a/Makerules b/Makerules
index 318a916eef0..d7ab610b294 100644
--- a/Makerules
+++ b/Makerules
@@ -1214,6 +1214,19 @@ check: tests
 xcheck: xtests
 endif
 
+# 'make check-parallel' runs the whole suite with maximum concurrency:
+# serialize-tests=no drops the per-subdirectory .NOTPARALLEL and the run-time
+# ordering, so every test builds and runs in parallel.  A single pass suffices
+# (there is no .NOTPARALLEL to work around, so the test programs already build
+# concurrently).
+# This is faster on an idle machine, at the cost of possible flakiness in the
+# timing-sensitive tests under the heavier load.
+.PHONY: check-parallel xcheck-parallel
+check-parallel:
+	$(MAKE) serialize-tests=no tests
+xcheck-parallel:
+	$(MAKE) serialize-tests=no xtests
+
 # Also handle test inputs in sysdeps.
 vpath %.input $(sysdirs)
 
diff --git a/htl/Makefile b/htl/Makefile
index 0e5a8b8f689..1035b075649 100644
--- a/htl/Makefile
+++ b/htl/Makefile
@@ -258,8 +258,9 @@ else
 $(addprefix $(objpfx),$(tests) $(test-srcs)): $(srcdir)/libpthread_syms.a $(objpfx)libpthread.a
 endif
 
-# The tests here better do not run in parallel.
-ifeq ($(run-built-tests),yes)
+# The tests here better do not run in parallel, unless serialize-tests is
+# cleared (make check-parallel).
+ifeq (yes-yes,$(run-built-tests)-$(serialize-tests))
 ifneq ($(filter %tests,$(MAKECMDGOALS)),)
 .NOTPARALLEL:
 endif
diff --git a/nptl/Makefile b/nptl/Makefile
index 02862d1c04b..97a0fb7f658 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -738,8 +738,9 @@ tst-audit-threads-ENV = LD_AUDIT=$(objpfx)tst-audit-threads-mod1.so
 tst-setuid1-static-ENV = \
   LD_LIBRARY_PATH=$(ld-library-path):$(common-objpfx)elf:$(common-objpfx)nss
 
-# The tests here better do not run in parallel.
-ifeq ($(run-built-tests),yes)
+# The tests here better do not run in parallel, unless serialize-tests is
+# cleared (make check-parallel).
+ifeq (yes-yes,$(run-built-tests)-$(serialize-tests))
 ifneq ($(filter %tests,$(MAKECMDGOALS)),)
 .NOTPARALLEL:
 endif
diff --git a/rt/Makefile b/rt/Makefile
index 24e43a87599..f39e9674e58 100644
--- a/rt/Makefile
+++ b/rt/Makefile
@@ -111,8 +111,9 @@ $(objpfx)librt.so: $(shared-thread-library)
 tst-mqueue7-ARGS = -- $(host-test-program-cmd)
 
 # The timer and message-queue tests here are timing-sensitive and better
-# do not run in parallel.
-ifeq ($(run-built-tests),yes)
+# do not run in parallel, unless serialize-tests is cleared (make
+# check-parallel).
+ifeq (yes-yes,$(run-built-tests)-$(serialize-tests))
 ifneq ($(filter %tests,$(MAKECMDGOALS)),)
 .NOTPARALLEL:
 endif
-- 
2.43.0