Rewrite ethread library

Large parts of the ethread library have been rewritten. The
ethread library is an Erlang runtime system internal, portable
thread library used by the runtime system itself.

Most notable improvement is a reader optimized rwlock
implementation which dramatically improve the performance of
read-lock/read-unlock operations on multi processor systems by
avoiding ping-ponging of the rwlock cache lines. The reader
optimized rwlock implementation is used by miscellaneous
rwlocks in the runtime system that are known to be read-locked
frequently, and can be enabled on ETS tables by passing the
`{read_concurrency, true}' option upon table creation. See the
documentation of `ets:new/2' for more information.

The ethread library can now also use the libatomic_ops library
for atomic memory accesses. This makes it possible for the
Erlang runtime system to utilize optimized atomic operations
on more platforms than before. Use the
`--with-libatomic_ops=PATH' configure command line argument
when specifying where the libatomic_ops installation is
located. The libatomic_ops library can be downloaded from:
http://www.hpl.hp.com/research/linux/atomic_ops/

The changed API of the ethread library has also caused
modifications in the Erlang runtime system. Preparations for
the to come "delayed deallocation" feature has also been done
since it depends on the ethread library.

Note: When building for x86, the ethread library will now use
instructions that first appeared on the pentium 4 processor. If
you want the runtime system to be compatible with older
processors (back to 486) you need to pass the
`--enable-ethread-pre-pentium4-compatibility' configure command
line argument when configuring the system.

1 files changed, 151 insertions, 0 deletions

diff --git a/erts/include/internal/pthread/ethr_event.h b/erts/include/internal/pthread/ethr_event.h
new file mode 100644
index 0000000000..104ec287e0
--- /dev/null
+++ b/erts/include/internal/pthread/ethr_event.h
@@ -0,0 +1,151 @@
+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson AB 2009-2010. 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%
+ */
+
+/*
+ * Author: Rickard Green
+ */
+
+#if defined(ETHR_HAVE_LINUX_FUTEX) && defined(ETHR_HAVE_NATIVE_ATOMICS)
+/* --- Linux futex implementation of ethread events ------------------------- */
+#define ETHR_LINUX_FUTEX_IMPL__
+
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <linux/futex.h>
+#include <sys/time.h>
+
+/*
+ * Note: Linux futexes operate on 32-bit integers, but
+ *       ethr_native_atomic_t are 64-bits on 64-bit
+ *       platforms. This has to be taken into account.
+ *       Therefore, in each individual value used each
+ *       byte look the same.
+ */
+
+#if ETHR_SIZEOF_PTR == 8
+
+#define ETHR_EVENT_OFF_WAITER__		0xffffffffffffffffL
+#define ETHR_EVENT_OFF__		0x7777777777777777L
+#define ETHR_EVENT_ON__ 		0L
+
+#elif  ETHR_SIZEOF_PTR == 4
+
+#define ETHR_EVENT_OFF_WAITER__		0xffffffffL
+#define ETHR_EVENT_OFF__		0x77777777L
+#define ETHR_EVENT_ON__ 		0L
+
+#else
+
+#error ehrm...
+
+#endif
+
+#if defined(FUTEX_WAIT_PRIVATE) && defined(FUTEX_WAKE_PRIVATE)
+#  define ETHR_FUTEX_WAIT__ FUTEX_WAIT_PRIVATE
+#  define ETHR_FUTEX_WAKE__ FUTEX_WAKE_PRIVATE
+#else
+#  define ETHR_FUTEX_WAIT__ FUTEX_WAIT
+#  define ETHR_FUTEX_WAKE__ FUTEX_WAKE
+#endif
+
+typedef struct {
+    ethr_atomic_t futex;
+} ethr_event;
+
+#define ETHR_FUTEX__(FTX, OP, VAL) \
+  (-1 == syscall(__NR_futex, (void *) (FTX), (OP), (int) (VAL), NULL, NULL, 0)\
+   ? errno : 0)
+
+#if defined(ETHR_TRY_INLINE_FUNCS) || defined(ETHR_EVENT_IMPL__)
+
+static void ETHR_INLINE
+ETHR_INLINE_FUNC_NAME_(ethr_event_set)(ethr_event *e)
+{
+    long val;
+    ETHR_WRITE_MEMORY_BARRIER;
+    val = ethr_atomic_xchg(&e->futex, ETHR_EVENT_ON__);
+    if (val == ETHR_EVENT_OFF_WAITER__) {
+	int res = ETHR_FUTEX__(&e->futex, ETHR_FUTEX_WAKE__, 1);
+	if (res != 0)
+	    ETHR_FATAL_ERROR__(res);
+    }
+}
+
+static void ETHR_INLINE
+ETHR_INLINE_FUNC_NAME_(ethr_event_reset)(ethr_event *e)
+{
+    ethr_atomic_set(&e->futex, ETHR_EVENT_OFF__);
+    ETHR_MEMORY_BARRIER;
+}
+
+#endif
+
+#elif defined(ETHR_PTHREADS)
+/* --- Posix mutex/cond implementation of events ---------------------------- */
+
+typedef struct {
+    ethr_atomic_t state;
+    pthread_mutex_t mtx;
+    pthread_cond_t cnd;
+} ethr_event;
+
+#define ETHR_EVENT_OFF_WAITER__		-1L
+#define ETHR_EVENT_OFF__		1L
+#define ETHR_EVENT_ON__ 		0L
+
+#if defined(ETHR_TRY_INLINE_FUNCS) || defined(ETHR_EVENT_IMPL__)
+
+static void ETHR_INLINE
+ETHR_INLINE_FUNC_NAME_(ethr_event_set)(ethr_event *e)
+{
+    long val;
+    ETHR_WRITE_MEMORY_BARRIER;
+    val = ethr_atomic_xchg(&e->state, ETHR_EVENT_ON__);
+    if (val == ETHR_EVENT_OFF_WAITER__) {
+	int res = pthread_mutex_lock(&e->mtx);
+	if (res != 0)
+	    ETHR_FATAL_ERROR__(res);
+	res = pthread_cond_signal(&e->cnd);
+	if (res != 0)
+	    ETHR_FATAL_ERROR__(res);
+	res = pthread_mutex_unlock(&e->mtx);
+	if (res != 0)
+	    ETHR_FATAL_ERROR__(res);
+    }
+}
+
+static void ETHR_INLINE
+ETHR_INLINE_FUNC_NAME_(ethr_event_reset)(ethr_event *e)
+{
+    ethr_atomic_set(&e->state, ETHR_EVENT_OFF__);
+    ETHR_MEMORY_BARRIER;
+}
+
+#endif
+
+#endif
+
+int ethr_event_init(ethr_event *e);
+int ethr_event_destroy(ethr_event *e);
+int ethr_event_wait(ethr_event *e);
+int ethr_event_swait(ethr_event *e, int spincount);
+#if !defined(ETHR_TRY_INLINE_FUNCS) || defined(ETHR_EVENT_IMPL__)
+void ethr_event_set(ethr_event *e);
+void ethr_event_reset(ethr_event *e);
+#endif