> > For a while I though it might be because we are using an alpha TAS in
> > the spinlock rather than the old semaphore. I replaced our spinlock
> > with the standard one and it made no difference. We have been running
> > with our spinlock implementation for nearly 2 months on a production
> > database now without a hitch, so I think it is ok. Did I ever submit
> > any patches for the Alpha spinlock?
>
> Not that I recall. We did get some advice from some Alpha gurus at DEC
> who seemed to think the existing TAS code is OK. What was it that you
> felt needed to be improved?
The current code uses semaphores, which has the advantage that it works
well even on multi-processor machines, but the disadvantage that it is not
the fastest way possible. Writing a spinlock on Alpha for SMP machines is
very difficult, as you need to deal with memory barriers. A real mess. But
then one of the people at Compaq pointed out to us that there is a
ready-made routine on Alpha. We implemented it with the two patches below.
I ran tests with lots of parallel back-ends and got around a 10% speed
increase. I include the two patches. Perhaps some of the other people
running Tru64 can have a look at these as well.
Cheers,
Adriaan Joubert
#define USE_POSIX_TIME
#define DISABLE_XOPEN_NLS
#define HAS_TEST_AND_SET
-#include <sys/mman.h> /* for msemaphore */
-typedef msemaphore slock_t;
+/*#include <sys/mman.h>*/ /* for msemaphore */
+/*typedef msemaphore slock_t;*/
+#include <alpha/builtins.h>
+typedef volatile long slock_t;
/* some platforms define __alpha, but not __alpha__ */
#if defined(__alpha) && !defined(__alpha__)
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/include/storage/s_lock.h,v 1.71 2000/07/05 16:09:31 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/include/storage/s_lock.h,v 1.72 2000/10/08 04:38:21 momjian Exp $
*
*-------------------------------------------------------------------------
*/
* Note that slock_t on the Alpha AXP is msemaphore instead of char
* (see storage/ipc.h).
*/
+#include <alpha/builtins.h>
+#if 0
#define TAS(lock) (msem_lock((lock), MSEM_IF_NOWAIT) < 0)
#define S_UNLOCK(lock) msem_unlock((lock), 0)
#define S_INIT_LOCK(lock) msem_init((lock), MSEM_UNLOCKED)
#define S_LOCK_FREE(lock) (!(lock)->msem_state)
+#else
+#define TAS(lock) (__INTERLOCKED_TESTBITSS_QUAD((lock),0))
+#endif
#else /* i.e. not __osf__ */