| /* elision-conf.c: Lock elision tunable parameters. |
| Copyright (C) 2013-2014 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 <init-arch.h> |
| #include <elision-conf.h> |
| #include <unistd.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 we retry 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. */ |
| .retry_try_xbegin = 3, |
| /* Same as SKIP_LOCK_INTERNAL_ABORT but for trylock. */ |
| .skip_trylock_internal_abort = 3, |
| }; |
| |
| /* Set when the CPU supports elision. When false elision is never attempted. |
| */ |
| |
| int __elision_available attribute_hidden; |
| |
| /* 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; |
| |
| /* Initialize elison. */ |
| |
| static void |
| elision_init (int argc __attribute__ ((unused)), |
| char **argv __attribute__ ((unused)), |
| char **environ) |
| { |
| __elision_available = HAS_RTM; |
| #ifdef ENABLE_LOCK_ELISION |
| __pthread_force_elision = __libc_enable_secure ? 0 : __elision_available; |
| #endif |
| } |
| |
| #ifdef SHARED |
| # define INIT_SECTION ".init_array" |
| #else |
| # define INIT_SECTION ".preinit_array" |
| #endif |
| |
| void (*const __pthread_init_array []) (int, char **, char **) |
| __attribute__ ((section (INIT_SECTION), aligned (sizeof (void *)))) = |
| { |
| &elision_init |
| }; |