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authorCupertino Miranda <cupertino.miranda@oracle.com>2023-04-14 16:12:20 +0100
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2023-04-20 13:54:24 -0300
commitb630be0922dbaaa50eb174a7740f0d3fb88602da (patch)
treefa0e6bd1ef8115117c6a2090b2dd5248269609fb /nptl/allocatestack.c
parent0f61cd4b9c5175c128311769df932c8d7694d6b6 (diff)
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Created tunable to force small pages on stack allocation.
Created tunable glibc.pthread.stack_hugetlb to control when hugepages
can be used for stack allocation.
In case THP are enabled and glibc.pthread.stack_hugetlb is set to
0, glibc will madvise the kernel not to use allow hugepages for stack
allocations.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
Diffstat (limited to 'nptl/allocatestack.c')
-rw-r--r--nptl/allocatestack.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
index c7adbccd6f..f9d8cdfd08 100644
--- a/nptl/allocatestack.c
+++ b/nptl/allocatestack.c
@@ -369,6 +369,12 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
 	  if (__glibc_unlikely (mem == MAP_FAILED))
 	    return errno;
 
+	  /* Do madvise in case the tunable glibc.pthread.stack_hugetlb is
+	     set to 0, disabling hugetlb.  */
+	  if (__glibc_unlikely (__nptl_stack_hugetlb == 0)
+	      && __madvise (mem, size, MADV_NOHUGEPAGE) != 0)
+	    return errno;
+
 	  /* SIZE is guaranteed to be greater than zero.
 	     So we can never get a null pointer back from mmap.  */
 	  assert (mem != NULL);