+2012-08-15 Maxim Kuvyrkov <maxim@codesourcery.com>
+
+ * pthread_spin_lock.c: New file.
+ * pthread_spin_trylock.c: New file.
+
2012-08-08 Joseph Myers <joseph@codesourcery.com>
* allocatestack.c (setxid_signal_thread) [__ASSUME_TGKILL]: Make
--- /dev/null
+/* pthread_spin_lock -- lock a spin lock. Generic version.
+ Copyright (C) 2012 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 <atomic.h>
+#include "pthreadP.h"
+
+/* A machine-specific version can define SPIN_LOCK_READS_BETWEEN_CMPXCHG
+ to the number of plain reads that it's optimal to spin on between uses
+ of atomic_compare_and_exchange_val_acq. If spinning forever is optimal
+ then use -1. If no plain reads here would ever be optimal, use 0. */
+#ifndef SPIN_LOCK_READS_BETWEEN_CMPXCHG
+# warning machine-dependent file should define SPIN_LOCK_READS_BETWEEN_CMPXCHG
+# define SPIN_LOCK_READS_BETWEEN_CMPXCHG 1000
+#endif
+
+int
+pthread_spin_lock (pthread_spinlock_t *lock)
+{
+ /* atomic_exchange usually takes less instructions than
+ atomic_compare_and_exchange. On the other hand,
+ atomic_compare_and_exchange potentially generates less bus traffic
+ when the lock is locked.
+ We assume that the first try mostly will be successful, and we use
+ atomic_exchange. For the subsequent tries we use
+ atomic_compare_and_exchange. */
+ if (atomic_exchange_acq (lock, 1) == 0)
+ return 0;
+
+ do
+ {
+ /* The lock is contended and we need to wait. Going straight back
+ to cmpxchg is not a good idea on many targets as that will force
+ expensive memory synchronizations among processors and penalize other
+ running threads.
+ On the other hand, we do want to update memory state on the local core
+ once in a while to avoid spinning indefinitely until some event that
+ will happen to update local memory as a side-effect. */
+ if (SPIN_LOCK_READS_BETWEEN_CMPXCHG >= 0)
+ {
+ int wait = SPIN_LOCK_READS_BETWEEN_CMPXCHG;
+
+ while (*lock != 0 && wait > 0)
+ --wait;
+ }
+ else
+ {
+ while (*lock != 0)
+ ;
+ }
+ }
+ while (atomic_compare_and_exchange_val_acq (lock, 1, 0) != 0);
+
+ return 0;
+}
-/* Copyright (C) 2008 Free Software Foundation, Inc.
+/* pthread_spin_trylock -- trylock a spin lock. Generic version.
+ Copyright (C) 2012 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
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
+ License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <errno.h>
int
pthread_spin_trylock (pthread_spinlock_t *lock)
{
- return atomic_compare_and_exchange_val_acq (lock, 1, 0) ? EBUSY : 0;
+ return atomic_exchange_acq (lock, 1) ? EBUSY : 0;
}
+2012-08-15 Maxim Kuvyrkov <maxim@codesourcery.com>
+
+ * sysdeps/arm/nptl/pthread_spin_lock.c: Use generic code.
+ * sysdeps/arm/nptl/pthread_spin_trylock.c: Remove, use generic version.
+
2012-08-14 Roland McGrath <roland@hack.frob.com>
* sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h: Renamed to ...
+2012-08-15 Maxim Kuvyrkov <maxim@codesourcery.com>
+
+ * sysdeps/hppa/nptl/pthread_spin_lock.c: Use generic code.
+ * sysdeps/hppa/nptl/pthread_spin_trylock.c: Remove, use generic version.
+
2012-08-12 Mike Frysinger <vapier@gentoo.org>
* sysdeps/unix/sysv/linux/hppa/syscalls.list: Add prlimit64.
+2012-08-15 Maxim Kuvyrkov <maxim@codesourcery.com>
+
+ * sysdeps/m68k/nptl/pthread_spin_lock.c: Use generic code.
+ * sysdeps/m68k/nptl/pthread_spin_trylock.c: Remove, use generic version.
+
2012-08-10 Andreas Schwab <schwab@linux-m68k.org>
* sysdeps/m68k/ldsodefs.h (m68k_gnu_pltenter): Remove const on
+2012-08-15 Maxim Kuvyrkov <maxim@codesourcery.com>
+
+ * sysdeps/mips/nptl/pthread_spin_lock.S: Remove, use generic version.
+ * sysdeps/mips/nptl/pthread_spin_lock.c: New file.
+ * sysdeps/mips/nptl/pthread_spin_trylock.S: Remove, use generic version.
+
2012-08-15 Joseph Myers <joseph@codesourcery.com>
* sysdeps/mips/dl-lookup.c: Update from generic version.
-/* Copyright (C) 2008 Free Software Foundation, Inc.
+/* Copyright (C) 2008-2012 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
License along with the GNU C Library. If not, see
<http://www.gnu.org/licenses/>. */
-#include <atomic.h>
-#include "pthreadP.h"
+#define SPIN_LOCK_READS_BETWEEN_CMPXCHG 1000
-int
-pthread_spin_lock (pthread_spinlock_t *lock)
-{
- while (atomic_compare_and_exchange_val_acq (lock, 1, 0) != 0)
- while (*lock != 0)
- ;
-
- return 0;
-}
+/* We can't use the normal "#include <nptl/pthread_spin_lock.c>" because
+ it will resolve to this very file. Using "sysdeps/.." as reference to the
+ top level directory does the job. */
+#include <sysdeps/../nptl/pthread_spin_lock.c>
-/* Copyright (C) 2005 Free Software Foundation, Inc.
+/* Copyright (C) 2005-2012 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
License along with the GNU C Library. If not, see
<http://www.gnu.org/licenses/>. */
-#include <atomic.h>
-#include "pthreadP.h"
+#define SPIN_LOCK_READS_BETWEEN_CMPXCHG 1000
-int
-pthread_spin_lock (pthread_spinlock_t *lock)
-{
-#if 0
- volatile unsigned int *addr = __ldcw_align (lock);
-
- while (__ldcw (addr) == 0)
- while (*addr == 0) ;
-
- return 0;
-#endif
-
- while (atomic_compare_and_exchange_val_acq(lock, 1, 0) == 1)
- while (*lock == 1);
-
- return 0;
-}
+/* We can't use the normal "#include <nptl/pthread_spin_lock.c>" because
+ it will resolve to this very file. Using "sysdeps/.." as reference to the
+ top level directory does the job. */
+#include <sysdeps/../nptl/pthread_spin_lock.c>
+++ /dev/null
-/* Copyright (C) 2005 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 <errno.h>
-#include <atomic.h>
-#include "pthreadP.h"
-
-int
-pthread_spin_trylock (pthread_spinlock_t *lock)
-{
-#if 0
- volatile unsigned int *a = __ldcw_align (lock);
-
- return __ldcw (a) ? 0 : EBUSY;
-#endif
-
- return atomic_compare_and_exchange_val_acq(lock, 1, 0) ? EBUSY : 0;
-
-}
-/* Copyright (C) 2010 Free Software Foundation, Inc.
+/* Copyright (C) 2010-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Maxim Kuvyrkov <maxim@codesourcery.com>, 2010.
License along with the GNU C Library. If not, see
<http://www.gnu.org/licenses/>. */
-#include <atomic.h>
-#include "pthreadP.h"
+#define SPIN_LOCK_READS_BETWEEN_CMPXCHG 1000
-int
-pthread_spin_lock (pthread_spinlock_t *lock)
-{
- while (atomic_compare_and_exchange_val_acq(lock, 1, 0) != 0)
- while (*lock != 0)
- ;
-
- return 0;
-}
+/* We can't use the normal "#include <nptl/pthread_spin_lock.c>" because
+ it will resolve to this very file. Using "sysdeps/.." as reference to the
+ top level directory does the job. */
+#include <sysdeps/../nptl/pthread_spin_lock.c>
+++ /dev/null
-/* Copyright (C) 2005 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 <sys/asm.h>
-#include <sysdep.h>
-#include <sgidefs.h>
-
-ENTRY (pthread_spin_lock)
- .set push
-#if _MIPS_SIM == _ABIO32
- .set mips2
-#endif
-1: ll a2, 0(a0)
- li a1, 1
- bnez a2, 1b
- sc a1, 0(a0)
- beqz a1, 1b
- MIPS_SYNC
- .set pop
- li v0, 0
- ret
-PSEUDO_END (pthread_spin_lock)
-/* Copyright (C) 2010 Free Software Foundation, Inc.
+/* Copyright (C) 2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
- Contributed by Maxim Kuvyrkov <maxim@codesourcery.com>, 2010.
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 along with the GNU C Library. If not, see
<http://www.gnu.org/licenses/>. */
-#include <errno.h>
-#include <atomic.h>
-#include "pthreadP.h"
+#define SPIN_LOCK_READS_BETWEEN_CMPXCHG 1000
-int
-pthread_spin_trylock (pthread_spinlock_t *lock)
-{
- return atomic_compare_and_exchange_val_acq(lock, 1, 0) ? EBUSY : 0;
-}
+/* We can't use the normal "#include <nptl/pthread_spin_lock.c>" because
+ it will resolve to this very file. Using "sysdeps/.." as reference to the
+ top level directory does the job. */
+#include <sysdeps/../nptl/pthread_spin_lock.c>
+++ /dev/null
-/* Copyright (C) 2005 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 <sys/asm.h>
-#include <sysdep.h>
-#define _ERRNO_H 1
-#include <bits/errno.h>
-#include <sgidefs.h>
-
-ENTRY (pthread_spin_trylock)
- .set push
-#if _MIPS_SIM == _ABIO32
- .set mips2
-#endif
- ll a2, 0(a0)
- li a1, 1
- bnez a2, 1f
- sc a1, 0(a0)
- beqz a1, 1f
- MIPS_SYNC
- .set pop
- li v0, 0
- ret
-1: li v0, EBUSY
- ret
-PSEUDO_END (pthread_spin_trylock)
projects / external / glibc.git / commitdiff