From: Cupertino Miranda <cupertino.miranda@oracle.com>
To: libc-alpha@sourceware.org
Cc: jose.marchesi@oracle.com, elena.zannoni@oracle.com,
adhemerval.zanella@linaro.org,
Cupertino Miranda <cupertino.miranda@oracle.com>
Subject: [PATCH] Created tunable to force small pages on stack allocation.
Date: Fri, 10 Mar 2023 14:35:58 +0000 [thread overview]
Message-ID: <20230310143558.361825-2-cupertino.miranda@oracle.com> (raw)
In-Reply-To: <20230310143558.361825-1-cupertino.miranda@oracle.com>
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 | 23 +++++++++++++++++++++++
sysdeps/nptl/dl-tunables.list | 6 ++++++
5 files changed, 39 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 <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 */
+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..6934b048b8 100644
--- a/nptl/pthread_mutex_conf.c
+++ b/nptl/pthread_mutex_conf.c
@@ -24,6 +24,7 @@
#include <unistd.h> /* Get STDOUT_FILENO for _dl_printf. */
#include <elf/dl-tunables.h>
#include <nptl-stack.h>
+#include <malloc-hugepages.h>
struct mutex_config __mutex_aconf =
{
@@ -45,6 +46,26 @@ 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)
+{
+ enum malloc_thp_mode_t thp_mode = __malloc_thp_mode ();
+ /*
+ Only allow to change the default of this tunable if the system
+ does support and has either 'madvise' or 'always' mode. Otherwise
+ the madvise() call is wasteful.
+ */
+ switch(thp_mode)
+ {
+ case malloc_thp_mode_always:
+ case malloc_thp_mode_madvise:
+ __nptl_stack_hugetlb = (int32_t) valp->numval;
+ break;
+ default:
+ break;
+ }
+}
+
void
__pthread_tunables_init (void)
{
@@ -52,5 +73,7 @@ __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
+ }
}
}
--
2.30.2
next prev parent reply other threads:[~2023-03-10 14:36 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-10 14:35 Cupertino Miranda
2023-03-10 14:35 ` Cupertino Miranda [this message]
2023-03-13 7:54 ` Florian Weimer
2023-03-13 10:07 ` Cupertino Miranda
2023-03-13 17:10 ` Cupertino Miranda
2023-03-13 17:18 ` Cupertino Miranda
2023-03-13 17:15 ` Adhemerval Zanella Netto
2023-03-13 17:32 ` Cupertino Miranda
2023-03-13 17:17 ` Cupertino Miranda
2023-03-20 15:41 [v2] Created tunable to force small pages on stack Cupertino Miranda
2023-03-20 15:41 ` [PATCH] Created tunable to force small pages on stack allocation Cupertino Miranda
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