OTP-8661 Enable writer preferred pthread read/write locks on Linux

Writer preferred pthread read/write locks has been enabled on Linux.

3 files changed, 89 insertions, 20 deletions

diff --git a/erts/aclocal.m4 b/erts/aclocal.m4
index 6a92fa5653..61244c7cd3 100644
--- a/erts/aclocal.m4
+++ b/erts/aclocal.m4
@@ -512,6 +512,8 @@ dnl
 AC_DEFUN(LM_CHECK_THR_LIB,
 [
 
+NEED_NPTL_PTHREAD_H=no
+
 dnl win32?
 AC_MSG_CHECKING([for native win32 threads])
 if test "X$host_os" = "Xwin32"; then
@@ -585,7 +587,9 @@ dnl On ofs1 the '-pthread' switch should be used
 		fi
 		if test $nptl = yes; then
 		    need_nptl_incldir=no
-		    AC_CHECK_HEADER(nptl/pthread.h, need_nptl_incldir=yes)
+		    AC_CHECK_HEADER(nptl/pthread.h,
+				    [need_nptl_incldir=yes
+				     NEED_NPTL_PTHREAD_H=yes])
 		    if test $need_nptl_incldir = yes; then
 			# Ahh...
 			nptl_path="$C_INCLUDE_PATH:$CPATH"
@@ -799,6 +803,11 @@ case "$THR_LIB_NAME" in
 			AC_DEFINE(ETHR_HAVE_MIT_PTHREAD_H, 1, \
 [Define if the pthread.h header file is in pthread/mit directory.]))
 
+	if test $NEED_NPTL_PTHREAD_H = yes; then
+	    AC_DEFINE(ETHR_NEED_NPTL_PTHREAD_H, 1, \
+[Define if you need the <nptl/pthread.h> header file.])
+	fi
+
 	AC_CHECK_HEADER(sys/time.h, \
 			AC_DEFINE(ETHR_HAVE_SYS_TIME_H, 1, \
 [Define if you have the <sys/time.h> header file.]))
@@ -826,19 +835,49 @@ case "$THR_LIB_NAME" in
 	AC_CHECK_FUNC(pthread_spin_lock, \
 			AC_DEFINE(ETHR_HAVE_PTHREAD_SPIN_LOCK, 1, \
 [Define if you have the pthread_spin_lock function.]))
-	test "$force_linux_pthread_rwlocks" = "yes" || {
-	    force_linux_pthread_rwlocks=no
-	}
-	case "$force_linux_pthread_rwlocks-$host_os" in
-		no-linux*) # Writers may get starved
-			# TODO: write a test that tests the implementation
-			;;
-		*)
-			AC_CHECK_FUNC(pthread_rwlock_init, \
-				AC_DEFINE(ETHR_HAVE_PTHREAD_RWLOCK_INIT, 1, \
-[Define if you have a pthread_rwlock implementation that can be used.]))
-			;;
-	esac
+
+	have_pthread_rwlock_init=no
+	AC_CHECK_FUNC(pthread_rwlock_init, [have_pthread_rwlock_init=yes])
+	if test $have_pthread_rwlock_init = yes; then
+
+	    AC_DEFINE(ETHR_HAVE_PTHREAD_RWLOCK_INIT, 1, \
+[Define if you have a pthread_rwlock implementation that can be used.])
+
+	    ethr_have_pthread_rwlockattr_setkind_np=no
+	    AC_CHECK_FUNC(pthread_rwlockattr_setkind_np,
+			  [ethr_have_pthread_rwlockattr_setkind_np=yes])
+
+	    if test $ethr_have_pthread_rwlockattr_setkind_np = yes; then
+		AC_DEFINE(ETHR_HAVE_PTHREAD_RWLOCKATTR_SETKIND_NP, 1, \
+[Define if you have the pthread_rwlockattr_setkind_np() function.])
+
+		AC_MSG_CHECKING([for PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP])
+		ethr_pthread_rwlock_writer_nonrecursive_initializer_np=no
+		AC_TRY_LINK([
+				#if defined(ETHR_NEED_NPTL_PTHREAD_H)
+				#include <nptl/pthread.h>
+				#elif defined(ETHR_HAVE_MIT_PTHREAD_H)
+				#include <pthread/mit/pthread.h>
+				#elif defined(ETHR_HAVE_PTHREAD_H)
+				#include <pthread.h>
+				#endif
+			    ],
+			    [
+				pthread_rwlockattr_t *attr;
+				return pthread_rwlockattr_setkind_np(attr,
+				    PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
+			    ],
+			    [ethr_pthread_rwlock_writer_nonrecursive_initializer_np=yes])
+		AC_MSG_RESULT([$ethr_pthread_rwlock_writer_nonrecursive_initializer_np])
+		if test $ethr_pthread_rwlock_writer_nonrecursive_initializer_np = yes; then
+		    AC_DEFINE(ETHR_HAVE_PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP, 1, \
+[Define if you have the PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP rwlock attribute.])
+		fi
+	    fi
+	fi
+
+
+
 	AC_CHECK_FUNC(pthread_attr_setguardsize, \
 			AC_DEFINE(ETHR_HAVE_PTHREAD_ATTR_SETGUARDSIZE, 1, \
 [Define if you have the pthread_attr_setguardsize function.]))
diff --git a/erts/include/internal/ethread_header_config.h.in b/erts/include/internal/ethread_header_config.h.in
index cf25ad3f55..c9fd87c2f6 100644
--- a/erts/include/internal/ethread_header_config.h.in
+++ b/erts/include/internal/ethread_header_config.h.in
@@ -50,6 +50,13 @@
 /* Define if you have a pthread_rwlock implementation that can be used */
 #undef ETHR_HAVE_PTHREAD_RWLOCK_INIT
 
+/* Define if you have the pthread_rwlockattr_setkind_np() function. */
+#undef ETHR_HAVE_PTHREAD_RWLOCKATTR_SETKIND_NP
+
+/* Define if you have the PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP rwlock
+   attribute. */
+#undef ETHR_HAVE_PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP
+
 /* Define if you have gcc atomic operations */
 #undef ETHR_HAVE_GCC_ATOMIC_OPS
 
diff --git a/erts/lib_src/common/ethread.c b/erts/lib_src/common/ethread.c
index eb4d0cad20..a4ec4c448b 100644
--- a/erts/lib_src/common/ethread.c
+++ b/erts/lib_src/common/ethread.c
@@ -1,19 +1,19 @@
 /*
  * %CopyrightBegin%
- * 
- * Copyright Ericsson AB 2004-2009. All Rights Reserved.
- * 
+ *
+ * Copyright Ericsson AB 2004-2010. All Rights Reserved.
+ *
  * The contents of this file are subject to the Erlang Public License,
  * Version 1.1, (the "License"); you may not use this file except in
  * compliance with the License. You should have received a copy of the
  * Erlang Public License along with this software. If not, it can be
  * retrieved online at http://www.erlang.org/.
- * 
+ *
  * Software distributed under the License is distributed on an "AS IS"
  * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
  * the License for the specific language governing rights and limitations
  * under the License.
- * 
+ *
  * %CopyrightEnd%
  */
 
@@ -269,6 +269,11 @@ static ethr_mutex no_ethrs_mtx;
 #warning "Cannot enforce fork-safety"
 #endif
 
+#ifdef ETHR_HAVE_PTHREAD_RWLOCK_INIT
+static pthread_rwlockattr_t write_pref_attr_data;
+static pthread_rwlockattr_t *write_pref_attr;
+#endif
+
 /*
  * ----------------------------------------------------------------------------
  * Static functions
@@ -525,6 +530,24 @@ ethr_init(ethr_init_data *id)
     }
 #endif
 
+#ifdef ETHR_HAVE_PTHREAD_RWLOCK_INIT
+#if defined(ETHR_HAVE_PTHREAD_RWLOCKATTR_SETKIND_NP) \
+    && defined(ETHR_HAVE_PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP)
+    res = pthread_rwlockattr_init(&write_pref_attr_data);
+    if (res != 0)
+	goto error;
+    res = pthread_rwlockattr_setkind_np(
+	&write_pref_attr_data,
+	PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
+    if (res != 0)
+	goto error;
+    write_pref_attr = &write_pref_attr_data;
+#else
+    write_pref_attr = NULL;
+#endif
+#endif
+
+
     return 0;
 
  error:
@@ -1060,7 +1083,7 @@ ethr_rwmutex_init(ethr_rwmutex *rwmtx)
     }
     rwmtx->initialized = ETHR_RWMUTEX_INITIALIZED;
 #endif
-    return pthread_rwlock_init(&rwmtx->pt_rwlock, NULL);
+    return pthread_rwlock_init(&rwmtx->pt_rwlock, write_pref_attr);
 }
 
 int