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[PATCH 06/11] Only allow to enable/disable elision for a mutex when the CPU supports it
- From: Andi Kleen <andi at firstfloor dot org>
- To: libc-alpha at sourceware dot org
- Cc: Andi Kleen <ak at linux dot jf dot intel dot com>
- Date: Mon, 24 Jun 2013 11:24:45 -0700
- Subject: [PATCH 06/11] Only allow to enable/disable elision for a mutex when the CPU supports it
- References: <1372098290-29147-1-git-send-email-andi at firstfloor dot org>
From: Andi Kleen <ak@linux.intel.com>
This allows to leave out some extra checks for elision available
in the fast paths.
nptl/:
2013-06-24 Andi Kleen <ak@linux.intel.com>
* pthread_mutexattr_settype.c (pthread_mutexattr_settype_worker):
Add check for elision available.
(ENABLE_ELISION): Define to zero if not set.
* nptl/sysdeps/unix/sysv/linux/x86/pthread_mutexattr_settype.c:
New file to add a ENABLE_ELISION for x86 for pthread_mutexattr_settype.
---
nptl/pthread_mutexattr_settype.c | 9 +++++++++
.../sysv/linux/x86/pthread_mutexattr_settype.c | 22 ++++++++++++++++++++++
2 files changed, 31 insertions(+)
create mode 100644 nptl/sysdeps/unix/sysv/linux/x86/pthread_mutexattr_settype.c
diff --git a/nptl/pthread_mutexattr_settype.c b/nptl/pthread_mutexattr_settype.c
index 8897653..ae1be45 100644
--- a/nptl/pthread_mutexattr_settype.c
+++ b/nptl/pthread_mutexattr_settype.c
@@ -20,6 +20,10 @@
#include <pthreadP.h>
#include <shlib-compat.h>
+#ifndef ENABLE_ELISION
+#define ENABLE_ELISION 0
+#endif
+
static int
pthread_mutexattr_settype_worker (pthread_mutexattr_t *attr, int kind)
{
@@ -43,6 +47,11 @@ pthread_mutexattr_settype_worker (pthread_mutexattr_t *attr, int kind)
kind |= PTHREAD_MUTEX_NO_ELISION_NP;
}
+ /* When the CPU does not support elision never allow to set the elision
+ flags. */
+ if ((kind & PTHREAD_MUTEX_ELISION_FLAGS_NP) && !ENABLE_ELISION)
+ kind &= ~PTHREAD_MUTEX_ELISION_FLAGS_NP;
+
iattr = (struct pthread_mutexattr *) attr;
iattr->mutexkind = (iattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_BITS) | kind;
diff --git a/nptl/sysdeps/unix/sysv/linux/x86/pthread_mutexattr_settype.c b/nptl/sysdeps/unix/sysv/linux/x86/pthread_mutexattr_settype.c
new file mode 100644
index 0000000..bb3dee5
--- /dev/null
+++ b/nptl/sysdeps/unix/sysv/linux/x86/pthread_mutexattr_settype.c
@@ -0,0 +1,22 @@
+/* Copyright (C) 2013 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/>. */
+
+/* Enable the CPUID check for elision types in pthread_mutexattr_settype. */
+
+#include <elision-conf.h>
+#define ENABLE_ELISION (__elision_available != 0)
+#include "nptl/pthread_mutexattr_settype.c"
--
1.8.1.4