diff options
Diffstat (limited to 'REORG.TODO/sysdeps/unix/sysv/linux/powerpc/elision-trylock.c')
-rw-r--r-- | REORG.TODO/sysdeps/unix/sysv/linux/powerpc/elision-trylock.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/unix/sysv/linux/powerpc/elision-trylock.c b/REORG.TODO/sysdeps/unix/sysv/linux/powerpc/elision-trylock.c new file mode 100644 index 0000000000..ed244d3f12 --- /dev/null +++ b/REORG.TODO/sysdeps/unix/sysv/linux/powerpc/elision-trylock.c @@ -0,0 +1,69 @@ +/* elision-trylock.c: Lock eliding trylock for pthreads. + Copyright (C) 2015-2017 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 <pthread.h> +#include <pthreadP.h> +#include <lowlevellock.h> +#include <elision-conf.h> +#include "htm.h" + +#define aconf __elision_aconf + +/* Try to elide a futex trylock. FUTEX is the futex variable. ADAPT_COUNT is + the adaptation counter in the mutex. */ + +int +__lll_trylock_elision (int *futex, short *adapt_count) +{ + /* Implement POSIX semantics by forbiding nesting elided trylocks. */ + __libc_tabort (_ABORT_NESTED_TRYLOCK); + + /* Only try a transaction if it's worth it. */ + if (atomic_load_relaxed (adapt_count) > 0) + { + goto use_lock; + } + + if (__libc_tbegin (0)) + { + if (*futex == 0) + return 0; + + /* Lock was busy. This is never a nested transaction. + End it, and set the adapt count. */ + __libc_tend (0); + + if (aconf.skip_lock_busy > 0) + atomic_store_relaxed (adapt_count, aconf.skip_lock_busy); + } + else + { + if (_TEXASRU_FAILURE_PERSISTENT (__builtin_get_texasru ())) + { + /* A persistent failure indicates that a retry will probably + result in another failure. Use normal locking now and + for the next couple of calls. */ + if (aconf.skip_trylock_internal_abort > 0) + atomic_store_relaxed (adapt_count, + aconf.skip_trylock_internal_abort); + } + } + +use_lock: + return lll_trylock (*futex); +} |