[v2,1/1] Created tunable to force small pages on stack allocation.
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Patch applied to master at the time it was sent
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dj/TryBot-32bit |
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Build for i686
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Commit Message
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.
Changed from v1:
- removed the __malloc_thp_mode calls to check if hugetlb is
enabled.
---
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(+)
Comments
On 20/03/23 13:20, Cupertino Miranda via Libc-alpha wrote:
> 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.
>
> Changed from v1:
> - removed the __malloc_thp_mode calls to check if hugetlb is
> enabled.
Thanks for the patch, some comments below.
> ---
> 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)
Space before '('.
> + 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 <pthreadP.h>
>
> 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 */
Double space before '*/' and maybe put '1 is default' between brackets.
> +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
This does not match the comment above.
> + }
> }
> }
Please also update manual/tunables.texi with brief explanation of what this
tunable does, and what the possible options does.
@@ -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);
@@ -21,6 +21,7 @@
#include <pthreadP.h>
size_t __nptl_stack_cache_maxsize = 40 * 1024 * 1024;
+int32_t __nptl_stack_hugetlb = 1;
void
__nptl_stack_list_del (list_t *elem)
@@ -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)
@@ -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
@@ -33,5 +33,11 @@ glibc {
maxval: 1
default: 1
}
+ stack_hugetlb {
+ type: INT_32
+ minval: 0
+ maxval: 1
+ default: 0
+ }
}
}