
------------
Benchmarking
------------
There is a set a benchmarking programs in the
"tests" directory. These should be runnable using the
following command-lines corresponding to each of the possible
library builds:

MSVC:
nmake clean VC-bench
nmake clean VCE-bench
nmake clean VSE-bench

Mingw32:
make clean GC-bench
make clean GCE-bench

UWIN:
The benchtests are run as part of the testsuite.


Mutex benchtests
----------------

benchtest1 - Lock plus unlock on an unlocked mutex.
benchtest2 - Lock plus unlock on a locked mutex.
benchtest3 - Trylock on a locked mutex.
benchtest4 - Trylock plus unlock on an unlocked mutex.


Each test times up to three alternate synchronisation
implementations as a reference, and then times each of
the four mutex types provided by the library. Each is
described below:

Simple Critical Section
- uses a simple Win32 critical section. There is no
additional overhead for this case as there is in the
remaining cases.

POSIX mutex implemented using a Critical Section
- The old implementation which uses runtime adaptation
depending on the Windows variant being run on. When
the pthreads DLL was run on WinNT or higher then
POSIX mutexes would use Win32 Critical Sections.

POSIX mutex implemented using a Win32 Mutex
- The old implementation which uses runtime adaptation
depending on the Windows variant being run on. When
the pthreads DLL was run on Win9x then POSIX mutexes
would use Win32 Mutexes (because TryEnterCriticalSection
is not implemented on Win9x).

PTHREAD_MUTEX_DEFAULT
PTHREAD_MUTEX_NORMAL
PTHREAD_MUTEX_ERRORCHECK
PTHREAD_MUTEX_RECURSIVE
- The current implementation supports these mutex types.
The underlying basis of POSIX mutexes is now the same
irrespective of the Windows variant, and should therefore
have consistent performance.


Semaphore benchtests
--------------------

benchtest5 - Timing for various uncontended cases.


In all benchtests, the operation is repeated a large
number of times and an average is calculated. Loop
overhead is measured and subtracted from all test times.