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Commitbe58282

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Tom Lane wrote:
> > 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 workswell even on multi-processor machines, but the disadvantage that it is notthe fastest way possible. Writing a spinlock on Alpha for SMP machines isvery difficult, as you need to deal with memory barriers. A real mess. Butthen one of the people at Compaq pointed out to us that there is aready-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% speedincrease. I include the two patches. Perhaps some of the other peoplerunning Tru64 can have a look at these as well.Cheers,Adriaan Joubert
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‎src/include/port/osf.h

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@@ -1,8 +1,10 @@
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#defineUSE_POSIX_TIME
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#defineDISABLE_XOPEN_NLS
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#defineHAS_TEST_AND_SET
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#include<sys/mman.h>/* for msemaphore */
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typedefmsemaphoreslock_t;
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/*#include <sys/mman.h>*//* for msemaphore */
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/*typedef msemaphore slock_t;*/
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#include<alpha/builtins.h>
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typedefvolatilelongslock_t;
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/* some platforms define __alpha, but not __alpha__ */
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#if defined(__alpha)&& !defined(__alpha__)

‎src/include/storage/s_lock.h

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@@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/include/storage/s_lock.h,v 1.71 2000/07/05 16:09:31 momjian Exp $
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* $Header: /cvsroot/pgsql/src/include/storage/s_lock.h,v 1.72 2000/10/08 04:38:21 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -270,10 +270,15 @@ tas(slock_t *s_lock)
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* Note that slock_t on the Alpha AXP is msemaphore instead of char
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* (see storage/ipc.h).
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*/
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#include<alpha/builtins.h>
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#if0
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#defineTAS(lock) (msem_lock((lock), MSEM_IF_NOWAIT) < 0)
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#defineS_UNLOCK(lock) msem_unlock((lock), 0)
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#defineS_INIT_LOCK(lock)msem_init((lock), MSEM_UNLOCKED)
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#defineS_LOCK_FREE(lock) (!(lock)->msem_state)
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#else
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#defineTAS(lock) (__INTERLOCKED_TESTBITSS_QUAD((lock),0))
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#endif
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#else/* i.e. not __osf__ */
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