Semaphore speedups - alpha, but passes testsuite

1 files changed, 61 insertions, 46 deletions

diff --git a/ChangeLog b/ChangeLog
index c1fe46f..88756a2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,40 +1,55 @@
-2004-10-15  Ross Johnson  <rpj at callisto.canberra.edu.au>
+2004-10-19  Ross Johnson  <rpj at callisto.canberra.edu.au>

 
-	* implement.h (othread_mutex_t_): Use an event in place of
-	the POSIX semaphore.
-	* pthread_mutex_init.c: Create the event; remove semaphore init.
-	* pthread_mutex_destroy.c: Delete the event.
-	* pthread_mutex_lock.c: Replace the semaphore wait with the event wait.
-	* pthread_mutex_trylock.c: Likewise.
-	* pthread_mutex_timedlock.c: Likewise.
-	* pthread_mutex_unlock.c: Set the event.
-	
+	* sem_init.c (sem_init): New semaphore model based on the same idea
+	as mutexes, i.e. user space interlocked check to avoid 
+	unnecessarily entering kernel space. Wraps the Win32 semaphore and
+	keeps it's own counter.
+	* sem_wait.c (sem_wait): Implemented user space check model.
+	* sem_post.c (sem_post): Likewise.
+	* sem_trywait.c (sem_trywait): Likewise.
+	* sem_timedwait.c (sem_timedwait): Likewise.
+	* sem_post_multiple.c (sem_post_multiple): Likewise.
+	* sem_getvalue.c (sem_getvalue): Likewise.
+	* ptw32_semwait.c (ptw32_semwait): Likewise.
+	* implement.h (sem_t_): Add counter element.
+
+2004-10-15  Ross Johnson  <rpj at callisto.canberra.edu.au>

+
+	* implement.h (othread_mutex_t_): Use an event in place of

+	the POSIX semaphore.

+	* pthread_mutex_init.c: Create the event; remove semaphore init.

+	* pthread_mutex_destroy.c: Delete the event.

+	* pthread_mutex_lock.c: Replace the semaphore wait with the event wait.

+	* pthread_mutex_trylock.c: Likewise.

+	* pthread_mutex_timedlock.c: Likewise.

+	* pthread_mutex_unlock.c: Set the event.

+	

 2004-10-14  Ross Johnson  <rpj at callisto.canberra.edu.au>

 
-	* pthread_mutex_lock.c (pthread_mutex_lock): New algorithm using
-	Terekhov's xchg based variation of Drepper's cmpxchg model.
-	Theoretically, xchg uses fewer clock cycles than cmpxchg (using IA-32
-	as a reference), however, in my opinion bus locking dominates the
-	equation on smp systems, so the model with the least number of bus
-	lock operations in the execution path should win, which is Terekhov's
-	variant. On IA-32 uni-processor systems, it's faster to use the
-	CMPXCHG instruction without locking the bus than to use the XCHG
-	instruction, which always locks the bus. This makes the two variants
-	equal for the non-contended lock (fast lane) execution path on up
-	IA-32. Testing shows that the xchg variant is faster on up IA-32 as
-	well if the test forces higher lock contention frequency, even though
-	kernel calls should be dominating the times (on up IA-32, both
-	variants used CMPXCHG instructions and neither locked the bus).
+	* pthread_mutex_lock.c (pthread_mutex_lock): New algorithm using

+	Terekhov's xchg based variation of Drepper's cmpxchg model.

+	Theoretically, xchg uses fewer clock cycles than cmpxchg (using IA-32

+	as a reference), however, in my opinion bus locking dominates the

+	equation on smp systems, so the model with the least number of bus

+	lock operations in the execution path should win, which is Terekhov's

+	variant. On IA-32 uni-processor systems, it's faster to use the

+	CMPXCHG instruction without locking the bus than to use the XCHG

+	instruction, which always locks the bus. This makes the two variants

+	equal for the non-contended lock (fast lane) execution path on up

+	IA-32. Testing shows that the xchg variant is faster on up IA-32 as

+	well if the test forces higher lock contention frequency, even though

+	kernel calls should be dominating the times (on up IA-32, both

+	variants used CMPXCHG instructions and neither locked the bus).

 	* pthread_mutex_timedlock.c pthread_mutex_timedlock(): Similarly.

 	* pthread_mutex_trylock.c (pthread_mutex_trylock): Similarly.

 	* pthread_mutex_unlock.c (pthread_mutex_unlock): Similarly.

-	* ptw32_InterlockedCompareExchange.c (ptw32_InterlockExchange): New
-	function.
-	(PTW32_INTERLOCKED_EXCHANGE): Sets up macro to use inlined
+	* ptw32_InterlockedCompareExchange.c (ptw32_InterlockExchange): New

+	function.

+	(PTW32_INTERLOCKED_EXCHANGE): Sets up macro to use inlined

 	ptw32_InterlockedExchange.

-	* implement.h (PTW32_INTERLOCKED_EXCHANGE): Set default to
+	* implement.h (PTW32_INTERLOCKED_EXCHANGE): Set default to

 	InterlockedExchange().

-	* Makefile: Building using /Ob2 so that asm sections within inline
+	* Makefile: Building using /Ob2 so that asm sections within inline

 	functions are inlined.

 
 2004-10-08  Ross Johnson  <rpj at callisto.canberra.edu.au>

@@ -42,16 +57,16 @@
 	* pthread_mutex_destroy.c (pthread_mutex_destroy): Critical Section

 	element is no longer required.

 	* pthread_mutex_init.c (pthread_mutex_init): Likewise.

-	* pthread_mutex_lock.c (pthread_mutex_lock): New algorithm following
-	Drepper's paper at http://people.redhat.com/drepper/futex.pdf, but
-	using the existing semaphore in place of the futex described in the
+	* pthread_mutex_lock.c (pthread_mutex_lock): New algorithm following

+	Drepper's paper at http://people.redhat.com/drepper/futex.pdf, but

+	using the existing semaphore in place of the futex described in the

 	paper. Idea suggested by Alexander Terekhov - see:

 	http://sources.redhat.com/ml/pthreads-win32/2003/msg00108.html

 	* pthread_mutex_timedlock.c pthread_mutex_timedlock(): Similarly.

 	* pthread_mutex_trylock.c (pthread_mutex_trylock): Similarly.

 	* pthread_mutex_unlock.c (pthread_mutex_unlock): Similarly.

-	* pthread_barrier_wait.c (pthread_barrier_wait): Use inlined version
-	of InterlockedCompareExchange() if possible - determined at
+	* pthread_barrier_wait.c (pthread_barrier_wait): Use inlined version

+	of InterlockedCompareExchange() if possible - determined at

 	build-time.

 	* pthread_spin_destroy.c pthread_spin_destroy(): Likewise.

 	* pthread_spin_lock.c pthread_spin_lock():Likewise.

@@ -59,29 +74,29 @@
 	* pthread_spin_unlock.c (pthread_spin_unlock):Likewise.

 	* ptw32_InterlockedCompareExchange.c: Sets up macro for inlined use.

 	* implement.h (pthread_mutex_t_): Remove Critical Section element.

-	(PTW32_INTERLOCKED_COMPARE_EXCHANGE): Set to default non-inlined
+	(PTW32_INTERLOCKED_COMPARE_EXCHANGE): Set to default non-inlined

 	version of InterlockedCompareExchange().

-	* private.c: Include ptw32_InterlockedCompareExchange.c first for
+	* private.c: Include ptw32_InterlockedCompareExchange.c first for

 	inlining.

-	* GNUmakefile: Add commandline option to use inlined
+	* GNUmakefile: Add commandline option to use inlined

 	InterlockedCompareExchange().

 	* Makefile: Likewise.

 
 2004-09-27  Ross Johnson  <rpj at callisto.canberra.edu.au>

 
-	* pthread_mutex_lock.c (pthread_mutex_lock): Separate
-	PTHREAD_MUTEX_NORMAL logic since we do not need to keep or check some
-	state required by other mutex types; do not check mutex pointer arg
-	for validity - leave this to the system since we are only checking
-	for NULL pointers. This should improve speed of NORMAL mutexes and
+	* pthread_mutex_lock.c (pthread_mutex_lock): Separate

+	PTHREAD_MUTEX_NORMAL logic since we do not need to keep or check some

+	state required by other mutex types; do not check mutex pointer arg

+	for validity - leave this to the system since we are only checking

+	for NULL pointers. This should improve speed of NORMAL mutexes and

 	marginally improve speed of other type.

 	* pthread_mutex_trylock.c (pthread_mutex_trylock): Likewise.

 	* pthread_mutex_unlock.c (pthread_mutex_unlock): Likewise; also avoid

-	entering the critical section for the no-waiters case, with approx.
+	entering the critical section for the no-waiters case, with approx.

 	30% reduction in lock/unlock overhead for this case.

 	* pthread_mutex_timedlock.c (pthread_mutex_timedlock): Likewise; also

-	no longer keeps mutex if post-timeout second attempt succeeds - this
-	will assist applications that wish to impose strict lock deadlines,
+	no longer keeps mutex if post-timeout second attempt succeeds - this

+	will assist applications that wish to impose strict lock deadlines,

 	rather than simply to escape from frozen locks.

 
 2004-09-09  Tristan Savatier  <tristan at mpegtv.com>

@@ -92,7 +107,7 @@
 	[Maintainer's note: the race condition is harmless on SPU systems

 	and only a problem on MPU systems if concurrent access results in an

 	exception (presumably generated by a hardware interrupt). There are

-	other instances of similar harmless race conditions that have not
+	other instances of similar harmless race conditions that have not

 	been identified as issues.]

 
 2004-09-09  Ross Johnson  <rpj at callisto.canberra.edu.au>