mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-30 08:40:07 +00:00
688903eb3e
* All files with FSF copyright notices: Update copyright dates using scripts/update-copyrights. * locale/programs/charmap-kw.h: Regenerated. * locale/programs/locfile-kw.h: Likewise.
147 lines
5.1 KiB
C
147 lines
5.1 KiB
C
/* Lock elision tunable parameters.
|
|
Copyright (C) 2014-2018 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#include <config.h>
|
|
#include <pthreadP.h>
|
|
#include <elision-conf.h>
|
|
#include <unistd.h>
|
|
#include <dl-procinfo.h>
|
|
|
|
#if HAVE_TUNABLES
|
|
# define TUNABLE_NAMESPACE elision
|
|
#endif
|
|
#include <elf/dl-tunables.h>
|
|
|
|
/* Reasonable initial tuning values, may be revised in the future.
|
|
This is a conservative initial value. */
|
|
|
|
struct elision_config __elision_aconf =
|
|
{
|
|
/* How often to not attempt to use elision if a transaction aborted
|
|
because the lock is already acquired. Expressed in number of lock
|
|
acquisition attempts. */
|
|
.skip_lock_busy = 3,
|
|
/* How often to not attempt to use elision if a transaction aborted due
|
|
to reasons other than other threads' memory accesses. Expressed in
|
|
number of lock acquisition attempts. */
|
|
.skip_lock_internal_abort = 3,
|
|
/* How often to not attempt to use elision if a lock used up all retries
|
|
without success. Expressed in number of lock acquisition attempts. */
|
|
.skip_lock_out_of_tbegin_retries = 3,
|
|
/* How often we try using elision if there is chance for the transaction
|
|
to finish execution (e.g., it wasn't aborted due to the lock being
|
|
already acquired. */
|
|
.try_tbegin = 3,
|
|
/* Same as SKIP_LOCK_INTERNAL_ABORT but for trylock. */
|
|
.skip_trylock_internal_abort = 3,
|
|
};
|
|
|
|
/* Force elision for all new locks. This is used to decide whether existing
|
|
DEFAULT locks should be automatically upgraded to elision in
|
|
pthread_mutex_lock(). Disabled for suid programs. Only used when elision
|
|
is available. */
|
|
|
|
int __pthread_force_elision attribute_hidden = 0;
|
|
|
|
#if HAVE_TUNABLES
|
|
static inline void
|
|
__always_inline
|
|
do_set_elision_enable (int32_t elision_enable)
|
|
{
|
|
/* Enable elision if it's avaliable in hardware. It's not necessary to check
|
|
if __libc_enable_secure isn't enabled since elision_enable will be set
|
|
according to the default, which is disabled. */
|
|
if (elision_enable == 1)
|
|
__pthread_force_elision = (GLRO (dl_hwcap) & HWCAP_S390_TE) ? 1 : 0;
|
|
}
|
|
|
|
/* The pthread->elision_enable tunable is 0 or 1 indicating that elision
|
|
should be disabled or enabled respectively. The feature will only be used
|
|
if it's supported by the hardware. */
|
|
|
|
void
|
|
TUNABLE_CALLBACK (set_elision_enable) (tunable_val_t *valp)
|
|
{
|
|
int32_t elision_enable = (int32_t) valp->numval;
|
|
do_set_elision_enable (elision_enable);
|
|
}
|
|
|
|
#define TUNABLE_CALLBACK_FNDECL(__name, __type) \
|
|
static inline void \
|
|
__always_inline \
|
|
do_set_elision_ ## __name (__type value) \
|
|
{ \
|
|
__elision_aconf.__name = value; \
|
|
} \
|
|
void \
|
|
TUNABLE_CALLBACK (set_elision_ ## __name) (tunable_val_t *valp) \
|
|
{ \
|
|
__type value = (__type) (valp)->numval; \
|
|
do_set_elision_ ## __name (value); \
|
|
}
|
|
|
|
TUNABLE_CALLBACK_FNDECL (skip_lock_busy, int32_t);
|
|
TUNABLE_CALLBACK_FNDECL (skip_lock_internal_abort, int32_t);
|
|
TUNABLE_CALLBACK_FNDECL (skip_lock_out_of_tbegin_retries, int32_t);
|
|
TUNABLE_CALLBACK_FNDECL (try_tbegin, int32_t);
|
|
TUNABLE_CALLBACK_FNDECL (skip_trylock_internal_abort, int32_t);
|
|
#endif
|
|
|
|
/* Initialize elison. */
|
|
|
|
static void
|
|
elision_init (int argc __attribute__ ((unused)),
|
|
char **argv __attribute__ ((unused)),
|
|
char **environ)
|
|
{
|
|
#if HAVE_TUNABLES
|
|
/* Elision depends on tunables and must be explicitly turned on by setting
|
|
the appropriate tunable on a supported platform. */
|
|
|
|
TUNABLE_GET (enable, int32_t,
|
|
TUNABLE_CALLBACK (set_elision_enable));
|
|
TUNABLE_GET (skip_lock_busy, int32_t,
|
|
TUNABLE_CALLBACK (set_elision_skip_lock_busy));
|
|
TUNABLE_GET (skip_lock_internal_abort, int32_t,
|
|
TUNABLE_CALLBACK (set_elision_skip_lock_internal_abort));
|
|
TUNABLE_GET (skip_lock_after_retries, int32_t,
|
|
TUNABLE_CALLBACK (set_elision_skip_lock_out_of_tbegin_retries));
|
|
TUNABLE_GET (tries, int32_t,
|
|
TUNABLE_CALLBACK (set_elision_try_tbegin));
|
|
TUNABLE_GET (skip_trylock_internal_abort, int32_t,
|
|
TUNABLE_CALLBACK (set_elision_skip_trylock_internal_abort));
|
|
#endif
|
|
|
|
if (!__pthread_force_elision)
|
|
__elision_aconf.try_tbegin = 0; /* Disable elision on rwlocks. */
|
|
}
|
|
|
|
#ifdef SHARED
|
|
# define INIT_SECTION ".init_array"
|
|
# define MAYBE_CONST
|
|
#else
|
|
# define INIT_SECTION ".preinit_array"
|
|
# define MAYBE_CONST const
|
|
#endif
|
|
|
|
void (*MAYBE_CONST __pthread_init_array []) (int, char **, char **)
|
|
__attribute__ ((section (INIT_SECTION), aligned (sizeof (void *)))) =
|
|
{
|
|
&elision_init
|
|
};
|