From a4c2392d52ae9864fb0a602a3959c9f6a39714e4 Mon Sep 17 00:00:00 2001 From: Cupertino Miranda Date: Mon, 6 Mar 2023 19:34:19 +0000 Subject: [PATCH] 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. --- nptl/allocatestack.c | 6 ++++++ nptl/nptl-stack.c | 1 + nptl/nptl-stack.h | 3 +++ nptl/pthread_mutex_conf.c | 8 ++++++++ sysdeps/nptl/dl-tunables.list | 6 ++++++ 5 files changed, 24 insertions(+) diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c index c7adbccd6f..c792c6ed1f 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); diff --git a/nptl/nptl-stack.c b/nptl/nptl-stack.c index 5eb7773575..e829711cb5 100644 --- a/nptl/nptl-stack.c +++ b/nptl/nptl-stack.c @@ -21,6 +21,7 @@ #include size_t __nptl_stack_cache_maxsize = 40 * 1024 * 1024; +int32_t __nptl_stack_hugetlb = 1; void __nptl_stack_list_del (list_t *elem) diff --git a/nptl/nptl-stack.h b/nptl/nptl-stack.h index 34f8bbb15e..d5b2612b4a 100644 --- a/nptl/nptl-stack.h +++ b/nptl/nptl-stack.h @@ -27,6 +27,9 @@ /* Maximum size of the cache, in bytes. 40 MiB by default. */ extern size_t __nptl_stack_cache_maxsize attribute_hidden; +/* Should allow stacks to use hugetlb. 1 is default */ +extern int32_t __nptl_stack_hugetlb; + /* Check whether the stack is still used or not. */ static inline bool __nptl_stack_in_use (struct pthread *pd) diff --git a/nptl/pthread_mutex_conf.c b/nptl/pthread_mutex_conf.c index 329c4cbb8f..60ef9095aa 100644 --- a/nptl/pthread_mutex_conf.c +++ b/nptl/pthread_mutex_conf.c @@ -45,6 +45,12 @@ TUNABLE_CALLBACK (set_stack_cache_size) (tunable_val_t *valp) __nptl_stack_cache_maxsize = valp->numval; } +static void +TUNABLE_CALLBACK (set_stack_hugetlb) (tunable_val_t *valp) +{ + __nptl_stack_hugetlb = (int32_t) valp->numval; +} + void __pthread_tunables_init (void) { @@ -52,5 +58,7 @@ __pthread_tunables_init (void) TUNABLE_CALLBACK (set_mutex_spin_count)); TUNABLE_GET (stack_cache_size, size_t, TUNABLE_CALLBACK (set_stack_cache_size)); + TUNABLE_GET (stack_hugetlb, int32_t, + TUNABLE_CALLBACK (set_stack_hugetlb)); } #endif diff --git a/sysdeps/nptl/dl-tunables.list b/sysdeps/nptl/dl-tunables.list index bd1ddb121d..22fa9e0d12 100644 --- a/sysdeps/nptl/dl-tunables.list +++ b/sysdeps/nptl/dl-tunables.list @@ -33,5 +33,11 @@ glibc { maxval: 1 default: 1 } + stack_hugetlb { + type: INT_32 + minval: 0 + maxval: 1 + default: 0 + } } } -- 2.38.1