From: Cupertino Miranda <cupertino.miranda@oracle.com>
To: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Cc: libc-alpha@sourceware.org, jose.marchesi@oracle.com,
elena.zannoni@oracle.com
Subject: Re: [PATCH v6 1/1] Created tunable to force small pages on stack allocation.
Date: Thu, 20 Apr 2023 21:21:57 +0100 [thread overview]
Message-ID: <87sfcu9ue2.fsf@oracle.com> (raw)
In-Reply-To: <257edd00-44f5-0da9-39dc-2ef21341a036@linaro.org>
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
>> + }
>> }
>> }
next prev parent reply other threads:[~2023-04-20 20:22 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-14 15:12 [PATCH v6 0/1] *** " 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 [this message]
2023-04-20 20:33 ` Adhemerval Zanella Netto
2023-04-20 20:52 ` Cupertino Miranda
-- strict thread matches above, loose matches on Subject: below --
2023-04-14 14:28 [PATCH v6 0/1] *** " Cupertino Miranda
2023-04-14 14:28 ` [PATCH v6 1/1] " Cupertino Miranda
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87sfcu9ue2.fsf@oracle.com \
--to=cupertino.miranda@oracle.com \
--cc=adhemerval.zanella@linaro.org \
--cc=elena.zannoni@oracle.com \
--cc=jose.marchesi@oracle.com \
--cc=libc-alpha@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).