malloc: Add madvise support for Transparent Huge Pages

Linux Transparent Huge Pages (THP) current supports three different
states: 'never', 'madvise', and 'always'.  The 'never' is
self-explanatory and 'always' will enable THP for all anonymous
pages.  However, 'madvise' is still the default for some system and
for such case THP will be only used if the memory range is explicity
advertise by the program through a madvise(MADV_HUGEPAGE) call.

To enable it a new tunable is provided, 'glibc.malloc.hugetlb',
where setting to a value diffent than 0 enables the madvise call.

This patch issues the madvise(MADV_HUGEPAGE) call after a successful
mmap() call at sysmalloc() with sizes larger than the default huge
page size.  The madvise() call is disable is system does not support
THP or if it has the mode set to "never" and on Linux only support
one page size for THP, even if the architecture supports multiple
sizes.

To test is a new rule is added tests-malloc-hugetlb1, which run the
addes tests with the required GLIBC_TUNABLE setting.

Checked on x86_64-linux-gnu.

Reviewed-by: DJ Delorie <dj@redhat.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/Rules b/Rules
index b1137afe71..5f5d9ba4cc 100644
--- a/Rules
+++ b/Rules
@@ -157,6 +157,7 @@ tests: $(tests:%=$(objpfx)%.out) $(tests-internal:%=$(objpfx)%.out) \
        $(tests-container:%=$(objpfx)%.out) \
        $(tests-mcheck:%=$(objpfx)%-mcheck.out) \
        $(tests-malloc-check:%=$(objpfx)%-malloc-check.out) \
+       $(tests-malloc-hugetlb1:%=$(objpfx)%-malloc-hugetlb1.out) \
        $(tests-special) $(tests-printers-out)
 xtests: tests $(xtests:%=$(objpfx)%.out) $(xtests-special)
 endif
@@ -168,6 +169,7 @@ tests-expected =
 else
 tests-expected = $(tests) $(tests-internal) $(tests-printers) \
 	$(tests-container) $(tests-malloc-check:%=%-malloc-check) \
+	$(tests-malloc-hugetlb1:%=%-malloc-hugetlb1) \
 	$(tests-mcheck:%=%-mcheck)
 endif
 tests:
@@ -196,6 +198,7 @@ binaries-pie-notests =
 endif
 binaries-mcheck-tests = $(tests-mcheck:%=%-mcheck)
 binaries-malloc-check-tests = $(tests-malloc-check:%=%-malloc-check)
+binaries-malloc-hugetlb1-tests = $(tests-malloc-hugetlb1:%=%-malloc-hugetlb1)
 else
 binaries-all-notests =
 binaries-all-tests = $(tests) $(tests-internal) $(xtests) $(test-srcs)
@@ -207,6 +210,7 @@ binaries-pie-tests =
 binaries-pie-notests =
 binaries-mcheck-tests =
 binaries-malloc-check-tests =
+binaries-malloc-hugetlb1-tests =
 endif
 
 binaries-pie = $(binaries-pie-tests) $(binaries-pie-notests)
@@ -247,6 +251,14 @@ $(addprefix $(objpfx),$(binaries-malloc-check-tests)): %-malloc-check: %.o \
 	$(+link-tests)
 endif
 
+ifneq "$(strip $(binaries-malloc-hugetlb1-tests))" ""
+$(addprefix $(objpfx),$(binaries-malloc-hugetlb1-tests)): %-malloc-hugetlb1: %.o \
+  $(link-extra-libs-tests) \
+  $(sort $(filter $(common-objpfx)lib%,$(link-libc))) \
+  $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
+	$(+link-tests)
+endif
+
 ifneq "$(strip $(binaries-pie-tests))" ""
 $(addprefix $(objpfx),$(binaries-pie-tests)): %: %.o \
   $(link-extra-libs-tests) \
@@ -284,6 +296,13 @@ $(1)-malloc-check-ENV = MALLOC_CHECK_=3 \
 endef
 $(foreach t,$(tests-malloc-check),$(eval $(call malloc-check-ENVS,$(t))))
 
+# All malloc-hugetlb1 tests will be run with GLIBC_TUNABLES=glibc.malloc.hugetlb=1
+define malloc-hugetlb1-ENVS
+$(1)-malloc-hugetlb1-ENV += GLIBC_TUNABLES=glibc.malloc.hugetlb=1
+endef
+$(foreach t,$(tests-malloc-hugetlb1),$(eval $(call malloc-hugetlb1-ENVS,$(t))))
+
+
 # mcheck tests need the debug DSO to support -lmcheck.
 define mcheck-ENVS
 $(1)-mcheck-ENV = LD_PRELOAD=$(common-objpfx)/malloc/libc_malloc_debug.so