From: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
To: Cupertino Miranda <cupertino.miranda@oracle.com>,
libc-alpha@sourceware.org
Cc: jose.marchesi@oracle.com, elena.zannoni@oracle.com
Subject: Re: [PATCH v2 1/1] Created tunable to force small pages on stack allocation.
Date: Mon, 20 Mar 2023 14:06:24 -0300 [thread overview]
Message-ID: <ecddfe14-3d21-caf7-beb5-44057a5b186c@linaro.org> (raw)
In-Reply-To: <20230320162048.550179-2-cupertino.miranda@oracle.com>
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.
prev parent reply other threads:[~2023-03-20 17:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-20 16:20 [PATCH v2 0/1] *** " Cupertino Miranda
2023-03-20 16:20 ` [PATCH v2 1/1] " Cupertino Miranda
2023-03-20 17:06 ` Adhemerval Zanella Netto [this message]
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