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, 19 insertions, 27 deletions

diff --git a/erts/emulator/beam/erl_process_lock.h b/erts/emulator/beam/erl_process_lock.h
index d71e5a0a6e..7cfc9893fa 100644
--- a/erts/emulator/beam/erl_process_lock.h
+++ b/erts/emulator/beam/erl_process_lock.h
@@ -255,11 +255,7 @@ void erts_proc_lc_unrequire_lock(Process *p, ErtsProcLocks locks);
 
 typedef struct {
     union {
-#if ERTS_PROC_LOCK_MUTEX_IMPL
-	erts_smp_mtx_t mtx;
-#else
 	erts_smp_spinlock_t spnlck;
-#endif
 	char buf[64]; /* Try to get locks in different cache lines */
     } u;
 } erts_pix_lock_t;
@@ -277,9 +273,12 @@ typedef struct {
   ((ErtsProcLocks) erts_smp_atomic_band(&(L)->flags, (long) (MSK)))
 #define ERTS_PROC_LOCK_FLGS_BOR_(L, MSK) \
   ((ErtsProcLocks) erts_smp_atomic_bor(&(L)->flags, (long) (MSK)))
-#define ERTS_PROC_LOCK_FLGS_CMPXCHG_(L, NEW, EXPECTED) \
-  ((ErtsProcLocks) erts_smp_atomic_cmpxchg(&(L)->flags, \
-                                           (long) (NEW), (long) (EXPECTED)))
+#define ERTS_PROC_LOCK_FLGS_CMPXCHG_ACQB_(L, NEW, EXPECTED) \
+  ((ErtsProcLocks) erts_smp_atomic_cmpxchg_acqb(&(L)->flags, \
+                                                (long) (NEW), (long) (EXPECTED)))
+#define ERTS_PROC_LOCK_FLGS_CMPXCHG_RELB_(L, NEW, EXPECTED) \
+  ((ErtsProcLocks) erts_smp_atomic_cmpxchg_relb(&(L)->flags, \
+                                                (long) (NEW), (long) (EXPECTED)))
 #define ERTS_PROC_LOCK_FLGS_READ_(L) \
   ((ErtsProcLocks) erts_smp_atomic_read(&(L)->flags))
 
@@ -289,6 +288,9 @@ ERTS_GLB_INLINE ErtsProcLocks erts_proc_lock_flags_band(erts_proc_lock_t *,
 							ErtsProcLocks);
 ERTS_GLB_INLINE ErtsProcLocks erts_proc_lock_flags_bor(erts_proc_lock_t *,
 						       ErtsProcLocks);
+ERTS_GLB_INLINE ErtsProcLocks erts_proc_lock_flags_cmpxchg(erts_proc_lock_t *,
+							   ErtsProcLocks,
+							   ErtsProcLocks);
 
 #if ERTS_GLB_INLINE_INCL_FUNC_DEF
 
@@ -322,7 +324,9 @@ erts_proc_lock_flags_cmpxchg(erts_proc_lock_t *lck, ErtsProcLocks new,
 
 #define ERTS_PROC_LOCK_FLGS_BAND_(L, MSK) erts_proc_lock_flags_band((L), (MSK))
 #define ERTS_PROC_LOCK_FLGS_BOR_(L, MSK) erts_proc_lock_flags_bor((L), (MSK))
-#define ERTS_PROC_LOCK_FLGS_CMPXCHG_(L, NEW, EXPECTED) \
+#define ERTS_PROC_LOCK_FLGS_CMPXCHG_ACQB_(L, NEW, EXPECTED) \
+  erts_proc_lock_flags_cmpxchg((L), (NEW), (EXPECTED))
+#define ERTS_PROC_LOCK_FLGS_CMPXCHG_RELB_(L, NEW, EXPECTED) \
   erts_proc_lock_flags_cmpxchg((L), (NEW), (EXPECTED))
 #define ERTS_PROC_LOCK_FLGS_READ_(L) ((L)->flags)
 
@@ -348,9 +352,9 @@ ERTS_GLB_INLINE ErtsProcLocks erts_smp_proc_raw_trylock__(Process *p,
 							  ErtsProcLocks locks);
 #ifdef ERTS_ENABLE_LOCK_COUNT
 ERTS_GLB_INLINE void erts_smp_proc_lock_x__(Process *,
-					  erts_pix_lock_t *,
-					  ErtsProcLocks,
-					  char *file, unsigned int line);
+					    erts_pix_lock_t *,
+					    ErtsProcLocks,
+					    char *file, unsigned int line);
 #else
 ERTS_GLB_INLINE void erts_smp_proc_lock__(Process *,
 					  erts_pix_lock_t *,
@@ -372,30 +376,18 @@ ERTS_GLB_INLINE void erts_proc_lock_op_debug(Process *, ErtsProcLocks, int);
 ERTS_GLB_INLINE void erts_pix_lock(erts_pix_lock_t *pixlck)
 {
     ERTS_LC_ASSERT(pixlck);
-#if ERTS_PROC_LOCK_MUTEX_IMPL
-    erts_smp_mtx_lock(&pixlck->u.mtx);
-#else
     erts_smp_spin_lock(&pixlck->u.spnlck);
-#endif
 }
 
 ERTS_GLB_INLINE void erts_pix_unlock(erts_pix_lock_t *pixlck)
 {
     ERTS_LC_ASSERT(pixlck);
-#if ERTS_PROC_LOCK_MUTEX_IMPL
-    erts_smp_mtx_unlock(&pixlck->u.mtx);
-#else
     erts_smp_spin_unlock(&pixlck->u.spnlck);
-#endif
 }
 
 ERTS_GLB_INLINE int erts_lc_pix_lock_is_locked(erts_pix_lock_t *pixlck)
 {
-#if ERTS_PROC_LOCK_MUTEX_IMPL
-    return erts_smp_lc_mtx_is_locked(&pixlck->u.mtx);
-#else
     return erts_smp_lc_spinlock_is_locked(&pixlck->u.spnlck);
-#endif
 }
 
 /*
@@ -417,9 +409,9 @@ erts_smp_proc_raw_trylock__(Process *p, ErtsProcLocks locks)
     ErtsProcLocks expct_lflgs = 0;
 
     while (1) {
-        ErtsProcLocks lflgs = ERTS_PROC_LOCK_FLGS_CMPXCHG_(&p->lock,
-							   expct_lflgs | locks,
-							   expct_lflgs);
+        ErtsProcLocks lflgs = ERTS_PROC_LOCK_FLGS_CMPXCHG_ACQB_(&p->lock,
+								expct_lflgs | locks,
+								expct_lflgs);
         if (ERTS_LIKELY(lflgs == expct_lflgs)) {
             /* We successfully grabbed all locks. */
             return 0;
@@ -535,7 +527,7 @@ erts_smp_proc_unlock__(Process *p,
 
         if (want_lflgs != old_lflgs) {
             ErtsProcLocks new_lflgs =
-                ERTS_PROC_LOCK_FLGS_CMPXCHG_(&p->lock, want_lflgs, old_lflgs);
+                ERTS_PROC_LOCK_FLGS_CMPXCHG_RELB_(&p->lock, want_lflgs, old_lflgs);
 
             if (new_lflgs != old_lflgs) {
                 /* cmpxchg failed, try again. */