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authorAdhemerval Zanella <azanella@linux.vnet.ibm.com>2014-11-07 12:30:56 -0500
committerAdhemerval Zanella <azanella@linux.vnet.ibm.com>2015-01-12 06:30:54 -0500
commit4b45943a6f62cfc239e79ad8902f5c7f71fd13ec (patch)
treee297f0a960da29f470318e704890fbd52bf77fef /sysdeps
parent8d2c0a593bdefd220be0822fb70de6b8d3bfd39d (diff)
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powerpc: Add adaptive elision to rwlocks
This patch adds support for lock elision using ISA 2.07 hardware transactional memory for rwlocks. The logic is similar to the one presented in pthread_mutex lock elision.
Diffstat (limited to 'sysdeps')
-rw-r--r--sysdeps/powerpc/nptl/elide.h111
-rw-r--r--sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h8
-rw-r--r--sysdeps/unix/sysv/linux/powerpc/elision-conf.c3
3 files changed, 119 insertions, 3 deletions
diff --git a/sysdeps/powerpc/nptl/elide.h b/sysdeps/powerpc/nptl/elide.h
new file mode 100644
index 0000000000..01572d99ce
--- /dev/null
+++ b/sysdeps/powerpc/nptl/elide.h
@@ -0,0 +1,111 @@
+/* elide.h: Generic lock elision support for powerpc.
+ Copyright (C) 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/>. */
+
+#ifndef ELIDE_PPC_H
+# define ELIDE_PPC_H
+
+#ifdef ENABLE_LOCK_ELISION
+# include <htm.h>
+# include <elision-conf.h>
+
+/* Returns true if the lock defined by is_lock_free as elided.
+ ADAPT_COUNT is a pointer to per-lock state variable. */
+
+static inline bool
+__elide_lock (uint8_t *adapt_count, int is_lock_free)
+{
+ if (*adapt_count > 0)
+ {
+ (*adapt_count)--;
+ return false;
+ }
+
+ for (int i = __elision_aconf.try_tbegin; i > 0; i--)
+ {
+ if (__builtin_tbegin (0))
+ {
+ if (is_lock_free)
+ return true;
+ /* Lock was busy. */
+ __builtin_tabort (_ABORT_LOCK_BUSY);
+ }
+ else
+ {
+ /* 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 (_TEXASRU_FAILURE_PERSISTENT (__builtin_get_texasru ()))
+ {
+ if (__elision_aconf.skip_lock_internal_abort > 0)
+ *adapt_count = __elision_aconf.skip_lock_internal_abort;
+ break;
+ }
+ /* Same logic as above, but for a number of temporary failures in a
+ a row. */
+ else if (__elision_aconf.skip_lock_out_of_tbegin_retries > 0
+ && __elision_aconf.try_tbegin > 0)
+ *adapt_count = __elision_aconf.skip_lock_out_of_tbegin_retries;
+ }
+ }
+
+ return false;
+}
+
+# define ELIDE_LOCK(adapt_count, is_lock_free) \
+ __elide_lock (&(adapt_count), is_lock_free)
+
+
+static inline bool
+__elide_trylock (uint8_t *adapt_count, int is_lock_free, int write)
+{
+ if (__elision_aconf.try_tbegin > 0)
+ {
+ if (write)
+ __builtin_tabort (_ABORT_NESTED_TRYLOCK);
+ return __elide_lock (adapt_count, is_lock_free);
+ }
+ return false;
+}
+
+# define ELIDE_TRYLOCK(adapt_count, is_lock_free, write) \
+ __elide_trylock (&(adapt_count), is_lock_free, write)
+
+
+static inline bool
+__elide_unlock (int is_lock_free)
+{
+ if (is_lock_free)
+ {
+ __builtin_tend (0);
+ return true;
+ }
+ return false;
+}
+
+# define ELIDE_UNLOCK(is_lock_free) \
+ __elide_unlock (is_lock_free)
+
+# else
+
+# define ELIDE_LOCK(adapt_count, is_lock_free) 0
+# define ELIDE_TRYLOCK(adapt_count, is_lock_free, write) 0
+# define ELIDE_UNLOCK(is_lock_free) 0
+
+#endif /* ENABLE_LOCK_ELISION */
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h b/sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h
index 0f971cdf21..7cbdb2cb77 100644
--- a/sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h
+++ b/sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h
@@ -172,11 +172,13 @@ typedef union
unsigned int __nr_writers_queued;
int __writer;
int __shared;
- unsigned long int __pad1;
+ unsigned char __rwelision;
+ unsigned char __pad1[7];
unsigned long int __pad2;
/* FLAGS must stay at this position in the structure to maintain
binary compatibility. */
unsigned int __flags;
+# define __PTHREAD_RWLOCK_ELISION_EXTRA 0, {0, 0, 0, 0, 0, 0, 0 }
} __data;
# else
struct
@@ -187,20 +189,20 @@ typedef union
unsigned int __writer_wakeup;
unsigned int __nr_readers_queued;
unsigned int __nr_writers_queued;
- unsigned char __pad1;
+ unsigned char __rwelision;
unsigned char __pad2;
unsigned char __shared;
/* FLAGS must stay at this position in the structure to maintain
binary compatibility. */
unsigned char __flags;
int __writer;
+#define __PTHREAD_RWLOCK_ELISION_EXTRA 0
} __data;
# endif
char __size[__SIZEOF_PTHREAD_RWLOCK_T];
long int __align;
} pthread_rwlock_t;
-#define __PTHREAD_RWLOCK_ELISION_EXTRA 0
typedef union
{
diff --git a/sysdeps/unix/sysv/linux/powerpc/elision-conf.c b/sysdeps/unix/sysv/linux/powerpc/elision-conf.c
index 1d962e1d20..70fbbb2215 100644
--- a/sysdeps/unix/sysv/linux/powerpc/elision-conf.c
+++ b/sysdeps/unix/sysv/linux/powerpc/elision-conf.c
@@ -63,6 +63,9 @@ elision_init (int argc __attribute__ ((unused)),
int elision_available = (GLRO (dl_hwcap2) & PPC_FEATURE2_HAS_HTM) ? 1 : 0;
__pthread_force_elision = __libc_enable_secure ? 0 : elision_available;
#endif
+ if (!__pthread_force_elision)
+ /* Disable elision on rwlocks. */
+ __elision_aconf.try_tbegin = 0;
}
#ifdef SHARED