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[PATCH] Optimise PowerPC Linux pthread_spin_unlock
- From: Anton Blanchard <anton at samba dot org>
- To: libc-alpha at sources dot redhat dot com, sjmunroe at us dot ibm dot com
- Date: Thu, 9 Aug 2007 14:50:30 -0500
- Subject: [PATCH] Optimise PowerPC Linux pthread_spin_unlock
We can use lwsync instead of sync when unlocking a spinlock. Testing a
pthread_spin_lock/pthread_spin_unlock pair on a POWER5 box we see a
speedup as expected:
baseline: 148.51 cycles
patched: 130.17 cycles
Anton
--
2007-08-09 Anton Blanchard <anton@samba.org>
* sysdeps/unix/sysv/linux/powerpc/pthread_spin_unlock.c: New file.
diff -ruN libc/nptl/sysdeps/unix/sysv/linux/powerpc/pthread_spin_unlock.c libc.work/nptl/sysdeps/unix/sysv/linux/powerpc/pthread_spin_unlock.c
--- libc/nptl/sysdeps/unix/sysv/linux/powerpc/pthread_spin_unlock.c 1969-12-31 18:00:00.000000000 -0600
+++ libc.work/nptl/sysdeps/unix/sysv/linux/powerpc/pthread_spin_unlock.c 2007-08-09 13:53:09.000000000 -0500
@@ -0,0 +1,29 @@
+/* pthread_spin_unlock -- unlock a spin lock. PowerPC version.
+ Copyright (C) 2007 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include "pthreadP.h"
+#include <lowlevellock.h>
+
+int
+pthread_spin_unlock (pthread_spinlock_t *lock)
+{
+ __asm __volatile (__lll_rel_instr ::: "memory");
+ *lock = 0;
+ return 0;
+}