New pthread rwlock that is more scalable.

This replaces the pthread rwlock with a new implementation that uses a
more scalable algorithm (primarily through not using a critical section
anymore to make state changes).  The fast path for rdlock acquisition and
release is now basically a single atomic read-modify write or CAS and a few
branches.  See nptl/pthread_rwlock_common.c for details.

	* nptl/DESIGN-rwlock.txt: Remove.
	* nptl/lowlevelrwlock.sym: Remove.
	* nptl/Makefile: Add new tests.
	* nptl/pthread_rwlock_common.c: New file.  Contains the new rwlock.
	* nptl/pthreadP.h (PTHREAD_RWLOCK_PREFER_READER_P): Remove.
	(PTHREAD_RWLOCK_WRPHASE, PTHREAD_RWLOCK_WRLOCKED,
	PTHREAD_RWLOCK_RWAITING, PTHREAD_RWLOCK_READER_SHIFT,
	PTHREAD_RWLOCK_READER_OVERFLOW, PTHREAD_RWLOCK_WRHANDOVER,
	PTHREAD_RWLOCK_FUTEX_USED): New.
	* nptl/pthread_rwlock_init.c (__pthread_rwlock_init): Adapt to new
	implementation.
	* nptl/pthread_rwlock_rdlock.c (__pthread_rwlock_rdlock_slow): Remove.
	(__pthread_rwlock_rdlock): Adapt.
	* nptl/pthread_rwlock_timedrdlock.c
	(pthread_rwlock_timedrdlock): Adapt.
	* nptl/pthread_rwlock_timedwrlock.c
	(pthread_rwlock_timedwrlock): Adapt.
	* nptl/pthread_rwlock_trywrlock.c (pthread_rwlock_trywrlock): Adapt.
	* nptl/pthread_rwlock_tryrdlock.c (pthread_rwlock_tryrdlock): Adapt.
	* nptl/pthread_rwlock_unlock.c (pthread_rwlock_unlock): Adapt.
	* nptl/pthread_rwlock_wrlock.c (__pthread_rwlock_wrlock_slow): Remove.
	(__pthread_rwlock_wrlock): Adapt.
	* nptl/tst-rwlock10.c: Adapt.
	* nptl/tst-rwlock11.c: Adapt.
	* nptl/tst-rwlock17.c: New file.
	* nptl/tst-rwlock18.c: New file.
	* nptl/tst-rwlock19.c: New file.
	* nptl/tst-rwlock2b.c: New file.
	* nptl/tst-rwlock8.c: Adapt.
	* nptl/tst-rwlock9.c: Adapt.
	* sysdeps/aarch64/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/arm/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/hppa/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/ia64/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/m68k/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/microblaze/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/mips/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/nios2/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/s390/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/sh/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/sparc/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/tile/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/unix/sysv/linux/alpha/bits/pthreadtypes.h
	(pthread_rwlock_t): Adapt.
	* sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h
	(pthread_rwlock_t): Adapt.
	* sysdeps/x86/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* nptl/nptl-printers.py (): Adapt.
	* nptl/nptl_lock_constants.pysym: Adapt.
	* nptl/test-rwlock-printers.py: Adapt.
	* nptl/test-rwlockattr-printers.c: Adapt.
	* nptl/test-rwlockattr-printers.py: Adapt.

1 files changed, 0 insertions, 113 deletions

diff --git a/nptl/DESIGN-rwlock.txt b/nptl/DESIGN-rwlock.txt
deleted file mode 100644
index 810d1b8..0000000
--- a/nptl/DESIGN-rwlock.txt
+++ /dev/null
@@ -1,113 +0,0 @@
-Reader Writer Locks pseudocode
-==============================
-
-	pthread_rwlock_rdlock(pthread_rwlock_t *rwlock);
-	pthread_rwlock_unlock(pthread_rwlock_t *rwlock);
-	pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);
-
-struct pthread_rwlock_t {
-
-   unsigned int lock:
-         - internal mutex
-
-   unsigned int writers_preferred;
-         - locking mode: 0 recursive, readers preferred
-                         1 nonrecursive, writers preferred
-
-   unsigned int readers;
-         - number of read-only references various threads have
-
-   pthread_t writer;
-         - descriptor of the writer or 0
-
-   unsigned int readers_wakeup;
-         - 'all readers should wake up' futex.
-
-   unsigned int writer_wakeup;
-         - 'one writer should wake up' futex.
-
-   unsigned int nr_readers_queued;
-         - number of readers queued up.
-
-   unsigned int nr_writers_queued;
-         - number of writers queued up.
-}
-
-pthread_rwlock_rdlock(pthread_rwlock_t *rwlock)
-{
-  lll_lock(rwlock->lock);
-  for (;;) {
-    if (!rwlock->writer && (!rwlock->nr_writers_queued ||
-					!rwlock->writers_preferred))
-        break;
-
-    rwlock->nr_readers_queued++;
-    val = rwlock->readers_wakeup;
-    lll_unlock(rwlock->lock);
-
-    futex_wait(&rwlock->readers_wakeup, val)
-
-    lll_lock(rwlock->lock);
-    rwlock->nr_readers_queued--;
-  }
-  rwlock->readers++;
-  lll_unlock(rwlock->lock);
-}
-
-pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock)
-{
-  int result = EBUSY;
-  lll_lock(rwlock->lock);
-  if (!rwlock->writer && (!rwlock->nr_writers_queued ||
-					!rwlock->writers_preferred))
-    rwlock->readers++;
-  lll_unlock(rwlock->lock);
-  return result;
-}
-
-pthread_rwlock_wrlock(pthread_rwlock_t *rwlock)
-{
-  lll_lock(rwlock->lock);
-  for (;;) {
-    if (!rwlock->writer && !rwlock->readers)
-       break;
-
-    rwlock->nr_writers_queued++;
-    val = rwlock->writer_wakeup;
-    lll_unlock(rwlock->lock);
-
-    futex_wait(&rwlock->writer_wakeup, val);
-
-    lll_lock(rwlock->lock);
-    rwlock->nr_writers_queued--;
-  }
-  rwlock->writer = pthread_self();
-  lll_unlock(rwlock->lock);
-}
-
-pthread_rwlock_unlock(pthread_rwlock_t *rwlock)
-{
-  lll_lock(rwlock->lock);
-
-  if (rwlock->writer)
-    rwlock->writer = 0;
-  else
-    rwlock->readers--;
-
-  if (!rwlock->readers) {
-    if (rwlock->nr_writers_queued) {
-      ++rwlock->writer_wakeup;
-      lll_unlock(rwlock->lock);
-      futex_wake(&rwlock->writer_wakeup, 1);
-      return;
-    } else
-      if (rwlock->nr_readers_queued) {
-        ++rwlock->readers_wakeup;
-        lll_unlock(rwlock->lock);
-        futex_wake(&rwlock->readers_wakeup, MAX_INT);
-        return;
-      }
-  }
-
-  lll_unlock(rwlock->lock);
-}