* [PATCH v6 0/1] *** Created tunable to force small pages on stack allocation.
@ 2023-04-14 15:12 Cupertino Miranda
2023-04-14 15:12 ` [PATCH v6 1/1] " Cupertino Miranda
0 siblings, 1 reply; 9+ messages in thread
From: Cupertino Miranda @ 2023-04-14 15:12 UTC (permalink / raw)
To: libc-alpha; +Cc: jose.marchesi, elena.zannoni, Cupertino Miranda
Hi,
This is a correction to previous that failed to apply in
patchwork.
Regards,
Cupertino
Cupertino Miranda (1):
Created tunable to force small pages on stack allocation.
NEWS | 3 +++
manual/tunables.texi | 15 +++++++++++++++
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 ++++++
7 files changed, 42 insertions(+)
--
2.38.1
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v6 1/1] Created tunable to force small pages on stack allocation.
2023-04-14 15:12 [PATCH v6 0/1] *** Created tunable to force small pages on stack allocation Cupertino Miranda
@ 2023-04-14 15:12 ` Cupertino Miranda
2023-04-17 10:17 ` Florian Weimer
2023-04-20 16:55 ` Adhemerval Zanella Netto
0 siblings, 2 replies; 9+ messages in thread
From: Cupertino Miranda @ 2023-04-14 15:12 UTC (permalink / raw)
To: libc-alpha; +Cc: jose.marchesi, elena.zannoni, Cupertino Miranda
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.
Changed from v2:
- Added entry in manual/tunables.texi
- Fixed tunable default to description
- Code style corrections.
Changes from v3:
- Improve tunables.texi.
Changes from v4:
- Improved text in tunables.texi by suggestion of Adhemerval.
Changes from v5:
- Added a new entry in NEWS.
---
NEWS | 3 +++
manual/tunables.texi | 15 +++++++++++++++
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 ++++++
7 files changed, 42 insertions(+)
diff --git a/NEWS b/NEWS
index 83d082afad..40964d2ee0 100644
--- a/NEWS
+++ b/NEWS
@@ -21,6 +21,9 @@ Major new features:
* PRIb* and PRIB* macros from C2X have been added to <inttypes.h>.
+* A new tunable, glibc.pthread.stack_hugetlb, can be used to disable
+ Transparent Huge Pages (THP) in stack allocation at pthread_create.
+
Deprecated and removed features, and other changes affecting compatibility:
* In the Linux kernel for the hppa/parisc architecture some of the
diff --git a/manual/tunables.texi b/manual/tunables.texi
index 70dd2264c5..130f94b2bc 100644
--- a/manual/tunables.texi
+++ b/manual/tunables.texi
@@ -459,6 +459,21 @@ registration on behalf of the application.
Restartable sequences are a Linux-specific extension.
@end deftp
+@deftp Tunable glibc.pthread.stack_hugetlb
+This tunable controls whether to use Huge Pages in the stacks created by
+@code{pthread_create}. This tunable only affects the stacks created by
+@theglibc{}, it has no effect on stack assigned with
+@code{pthread_attr_setstack}.
+
+The default is @samp{1} where the system default value is used. Setting
+its value to @code{0} enables the use of @code{madvise} with
+@code{MADV_NOHUGEPAGE} after stack creation with @code{mmap}.
+
+This is a memory utilization optimization, since internal glibc setup of either
+the thread descriptor and the guard page might force the kernel to move the
+thread stack originally backup by Huge Pages to default pages.
+@end deftp
+
@node Hardware Capability Tunables
@section Hardware Capability Tunables
@cindex hardware capability tunables
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);
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..cf90b27c2b 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 9133384d47..6517899718 100644
--- a/nptl/pthread_mutex_conf.c
+++ b/nptl/pthread_mutex_conf.c
@@ -44,6 +44,12 @@ 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)
{
@@ -51,4 +57,6 @@ __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));
}
diff --git a/sysdeps/nptl/dl-tunables.list b/sysdeps/nptl/dl-tunables.list
index bd1ddb121d..4cde9500b6 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: 1
+ }
}
}
--
2.38.1
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v6 1/1] Created tunable to force small pages on stack allocation.
2023-04-14 15:12 ` [PATCH v6 1/1] " Cupertino Miranda
@ 2023-04-17 10:17 ` Florian Weimer
2023-04-17 13:32 ` Cupertino Miranda
2023-04-20 16:55 ` Adhemerval Zanella Netto
1 sibling, 1 reply; 9+ messages in thread
From: Florian Weimer @ 2023-04-17 10:17 UTC (permalink / raw)
To: Cupertino Miranda via Libc-alpha
Cc: Cupertino Miranda, jose.marchesi, elena.zannoni, tstuefe
* Cupertino Miranda via Libc-alpha:
> 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.
Is this for the benefit of OpenJDK (among other things)?
In this case, we should expose this in a pthread_attr_t interface as
well, so that OpenJDK can activate this easily for the required threads.
This can be done in a follow-up patch.
Thanks,
Florian
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v6 1/1] Created tunable to force small pages on stack allocation.
2023-04-17 10:17 ` Florian Weimer
@ 2023-04-17 13:32 ` Cupertino Miranda
0 siblings, 0 replies; 9+ messages in thread
From: Cupertino Miranda @ 2023-04-17 13:32 UTC (permalink / raw)
To: Florian Weimer
Cc: Cupertino Miranda via Libc-alpha, jose.marchesi, elena.zannoni, tstuefe
>> 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.
>
> Is this for the benefit of OpenJDK (among other things)?
Yes, it is actually. ;-)
>
> In this case, we should expose this in a pthread_attr_t interface as
> well, so that OpenJDK can activate this easily for the required threads.
> This can be done in a follow-up patch.
Totally aggree.
Our initial concern in proposing such change was to avoid big API
discussions when we were not sure if there was other simpler solution to
the problem.
I will work on such patches shortly if you think it is a good idea.
Thanks,
Cupertino
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v6 1/1] Created tunable to force small pages on stack allocation.
2023-04-14 15:12 ` [PATCH v6 1/1] " Cupertino Miranda
2023-04-17 10:17 ` Florian Weimer
@ 2023-04-20 16:55 ` Adhemerval Zanella Netto
2023-04-20 20:21 ` Cupertino Miranda
1 sibling, 1 reply; 9+ messages in thread
From: Adhemerval Zanella Netto @ 2023-04-20 16:55 UTC (permalink / raw)
To: Cupertino Miranda, libc-alpha; +Cc: jose.marchesi, elena.zannoni
On 14/04/23 12:12, 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.
>
> Changed from v2:
> - Added entry in manual/tunables.texi
> - Fixed tunable default to description
> - Code style corrections.
>
> Changes from v3:
> - Improve tunables.texi.
>
> Changes from v4:
> - Improved text in tunables.texi by suggestion of Adhemerval.
>
> Changes from v5:
> - Added a new entry in NEWS.
LGTM, thanks.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> NEWS | 3 +++
> manual/tunables.texi | 15 +++++++++++++++
> 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 ++++++
> 7 files changed, 42 insertions(+)
>
> diff --git a/NEWS b/NEWS
> index 83d082afad..40964d2ee0 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -21,6 +21,9 @@ Major new features:
>
> * PRIb* and PRIB* macros from C2X have been added to <inttypes.h>.
>
> +* A new tunable, glibc.pthread.stack_hugetlb, can be used to disable
> + Transparent Huge Pages (THP) in stack allocation at pthread_create.
> +
> Deprecated and removed features, and other changes affecting compatibility:
>
> * In the Linux kernel for the hppa/parisc architecture some of the
> diff --git a/manual/tunables.texi b/manual/tunables.texi
> index 70dd2264c5..130f94b2bc 100644
> --- a/manual/tunables.texi
> +++ b/manual/tunables.texi
> @@ -459,6 +459,21 @@ registration on behalf of the application.
> Restartable sequences are a Linux-specific extension.
> @end deftp
>
> +@deftp Tunable glibc.pthread.stack_hugetlb
> +This tunable controls whether to use Huge Pages in the stacks created by
> +@code{pthread_create}. This tunable only affects the stacks created by
> +@theglibc{}, it has no effect on stack assigned with
> +@code{pthread_attr_setstack}.
> +
> +The default is @samp{1} where the system default value is used. Setting
> +its value to @code{0} enables the use of @code{madvise} with
> +@code{MADV_NOHUGEPAGE} after stack creation with @code{mmap}.
> +
> +This is a memory utilization optimization, since internal glibc setup of either
> +the thread descriptor and the guard page might force the kernel to move the
> +thread stack originally backup by Huge Pages to default pages.
> +@end deftp
> +
> @node Hardware Capability Tunables
> @section Hardware Capability Tunables
> @cindex hardware capability tunables
> 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);
> 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..cf90b27c2b 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 9133384d47..6517899718 100644
> --- a/nptl/pthread_mutex_conf.c
> +++ b/nptl/pthread_mutex_conf.c
> @@ -44,6 +44,12 @@ 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)
> {
> @@ -51,4 +57,6 @@ __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));
> }
> diff --git a/sysdeps/nptl/dl-tunables.list b/sysdeps/nptl/dl-tunables.list
> index bd1ddb121d..4cde9500b6 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: 1
> + }
> }
> }
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v6 1/1] Created tunable to force small pages on stack allocation.
2023-04-20 16:55 ` Adhemerval Zanella Netto
@ 2023-04-20 20:21 ` Cupertino Miranda
2023-04-20 20:33 ` Adhemerval Zanella Netto
0 siblings, 1 reply; 9+ messages in thread
From: Cupertino Miranda @ 2023-04-20 20:21 UTC (permalink / raw)
To: Adhemerval Zanella Netto; +Cc: libc-alpha, jose.marchesi, elena.zannoni
Thanks !
Adhemerval Zanella Netto writes:
> On 14/04/23 12:12, 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.
>>
>> Changed from v2:
>> - Added entry in manual/tunables.texi
>> - Fixed tunable default to description
>> - Code style corrections.
>>
>> Changes from v3:
>> - Improve tunables.texi.
>>
>> Changes from v4:
>> - Improved text in tunables.texi by suggestion of Adhemerval.
>>
>> Changes from v5:
>> - Added a new entry in NEWS.
>
> LGTM, thanks.
>
> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
>
>> ---
>> NEWS | 3 +++
>> manual/tunables.texi | 15 +++++++++++++++
>> 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 ++++++
>> 7 files changed, 42 insertions(+)
>>
>> diff --git a/NEWS b/NEWS
>> index 83d082afad..40964d2ee0 100644
>> --- a/NEWS
>> +++ b/NEWS
>> @@ -21,6 +21,9 @@ Major new features:
>>
>> * PRIb* and PRIB* macros from C2X have been added to <inttypes.h>.
>>
>> +* A new tunable, glibc.pthread.stack_hugetlb, can be used to disable
>> + Transparent Huge Pages (THP) in stack allocation at pthread_create.
>> +
>> Deprecated and removed features, and other changes affecting compatibility:
>>
>> * In the Linux kernel for the hppa/parisc architecture some of the
>> diff --git a/manual/tunables.texi b/manual/tunables.texi
>> index 70dd2264c5..130f94b2bc 100644
>> --- a/manual/tunables.texi
>> +++ b/manual/tunables.texi
>> @@ -459,6 +459,21 @@ registration on behalf of the application.
>> Restartable sequences are a Linux-specific extension.
>> @end deftp
>>
>> +@deftp Tunable glibc.pthread.stack_hugetlb
>> +This tunable controls whether to use Huge Pages in the stacks created by
>> +@code{pthread_create}. This tunable only affects the stacks created by
>> +@theglibc{}, it has no effect on stack assigned with
>> +@code{pthread_attr_setstack}.
>> +
>> +The default is @samp{1} where the system default value is used. Setting
>> +its value to @code{0} enables the use of @code{madvise} with
>> +@code{MADV_NOHUGEPAGE} after stack creation with @code{mmap}.
>> +
>> +This is a memory utilization optimization, since internal glibc setup of either
>> +the thread descriptor and the guard page might force the kernel to move the
>> +thread stack originally backup by Huge Pages to default pages.
>> +@end deftp
>> +
>> @node Hardware Capability Tunables
>> @section Hardware Capability Tunables
>> @cindex hardware capability tunables
>> 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);
>> 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..cf90b27c2b 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 9133384d47..6517899718 100644
>> --- a/nptl/pthread_mutex_conf.c
>> +++ b/nptl/pthread_mutex_conf.c
>> @@ -44,6 +44,12 @@ 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)
>> {
>> @@ -51,4 +57,6 @@ __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));
>> }
>> diff --git a/sysdeps/nptl/dl-tunables.list b/sysdeps/nptl/dl-tunables.list
>> index bd1ddb121d..4cde9500b6 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: 1
>> + }
>> }
>> }
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v6 1/1] Created tunable to force small pages on stack allocation.
2023-04-20 20:21 ` Cupertino Miranda
@ 2023-04-20 20:33 ` Adhemerval Zanella Netto
2023-04-20 20:52 ` Cupertino Miranda
0 siblings, 1 reply; 9+ messages in thread
From: Adhemerval Zanella Netto @ 2023-04-20 20:33 UTC (permalink / raw)
To: Cupertino Miranda, Wilco Dijkstra
Cc: libc-alpha, jose.marchesi, elena.zannoni
On 20/04/23 17:21, Cupertino Miranda wrote:
>
> Thanks !
>
> Adhemerval Zanella Netto writes:
I also sent an updated patch to detect when the split will always
happen [1]. As I wrote in the patch, the tunable might still be
required in some specific scenarios, but it would be good to have
some heuristic to detect such scenarios if/when distros start to
active THP to be always enabled.
[1] https://patchwork.sourceware.org/project/glibc/patch/20230420172436.2013698-1-adhemerval.zanella@linaro.org/
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v6 1/1] Created tunable to force small pages on stack allocation.
2023-04-20 20:33 ` Adhemerval Zanella Netto
@ 2023-04-20 20:52 ` Cupertino Miranda
0 siblings, 0 replies; 9+ messages in thread
From: Cupertino Miranda @ 2023-04-20 20:52 UTC (permalink / raw)
To: Adhemerval Zanella Netto
Cc: Wilco Dijkstra, libc-alpha, jose.marchesi, elena.zannoni
> I also sent an updated patch to detect when the split will always
> happen [1]. As I wrote in the patch, the tunable might still be
> required in some specific scenarios, but it would be good to have
> some heuristic to detect such scenarios if/when distros start to
> active THP to be always enabled.
>
> [1] https://patchwork.sourceware.org/project/glibc/patch/20230420172436.2013698-1-adhemerval.zanella@linaro.org/
>
I have seen it and agree that it is useful.
I will attempt to test it tomorrow if you would be interested in the
feedback. I presume the condition is very similar to what I tested
before.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v6 1/1] Created tunable to force small pages on stack allocation.
2023-04-14 14:28 [PATCH v6 0/1] *** " Cupertino Miranda
@ 2023-04-14 14:28 ` Cupertino Miranda
0 siblings, 0 replies; 9+ messages in thread
From: Cupertino Miranda @ 2023-04-14 14:28 UTC (permalink / raw)
To: libc-alpha; +Cc: jose.marchesi, elena.zannoni, Cupertino Miranda
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.
Changed from v2:
- Added entry in manual/tunables.texi
- Fixed tunable default to description
- Code style corrections.
Changes from v3:
- Improve tunables.texi.
Changes from v4:
- Improved text in tunables.texi by suggestion of Adhemerval.
Changes from v5:
- Added a new entry in NEWS.
---
NEWS | 3 +++
manual/tunables.texi | 15 +++++++++++++++
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 ++++++
7 files changed, 42 insertions(+)
diff --git a/NEWS b/NEWS
index c54af824e0..941808049a 100644
--- a/NEWS
+++ b/NEWS
@@ -21,6 +21,9 @@ Major new features:
* PRIb* and PRIB* macros from C2X have been added to <inttypes.h>.
+* A new tunable, glibc.pthread.stack_hugetlb, can be used to disable
+ Transparent Huge Pages (THP) in stack allocation at pthread_create.
+
Deprecated and removed features, and other changes affecting compatibility:
* In the Linux kernel for the hppa/parisc architecture some of the
diff --git a/manual/tunables.texi b/manual/tunables.texi
index 70dd2264c5..130f94b2bc 100644
--- a/manual/tunables.texi
+++ b/manual/tunables.texi
@@ -459,6 +459,21 @@ registration on behalf of the application.
Restartable sequences are a Linux-specific extension.
@end deftp
+@deftp Tunable glibc.pthread.stack_hugetlb
+This tunable controls whether to use Huge Pages in the stacks created by
+@code{pthread_create}. This tunable only affects the stacks created by
+@theglibc{}, it has no effect on stack assigned with
+@code{pthread_attr_setstack}.
+
+The default is @samp{1} where the system default value is used. Setting
+its value to @code{0} enables the use of @code{madvise} with
+@code{MADV_NOHUGEPAGE} after stack creation with @code{mmap}.
+
+This is a memory utilization optimization, since internal glibc setup of either
+the thread descriptor and the guard page might force the kernel to move the
+thread stack originally backup by Huge Pages to default pages.
+@end deftp
+
@node Hardware Capability Tunables
@section Hardware Capability Tunables
@cindex hardware capability tunables
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);
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..cf90b27c2b 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..4cde9500b6 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: 1
+ }
}
}
--
2.38.1
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2023-04-20 20:52 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
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2023-04-14 15:12 [PATCH v6 0/1] *** Created tunable to force small pages on stack allocation Cupertino Miranda
2023-04-14 15:12 ` [PATCH v6 1/1] " Cupertino Miranda
2023-04-17 10:17 ` Florian Weimer
2023-04-17 13:32 ` Cupertino Miranda
2023-04-20 16:55 ` Adhemerval Zanella Netto
2023-04-20 20:21 ` Cupertino Miranda
2023-04-20 20:33 ` Adhemerval Zanella Netto
2023-04-20 20:52 ` Cupertino Miranda
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