The attached patch adds a module for testing and benchmarking mutexes,

The attached patch adds a module for testing and benchmarking mutexes,
semaphores and R/W semaphores.

Using it is simple:

	insmod synchro-test.ko <args>

It will exit with error ENOANO after running the tests and printing the
results to the kernel console log.

The available arguments are:

 (*) mx=N

	Start up to N mutex thrashing threads, where N is at most 20. All will
	try and thrash the same mutex.

 (*) sm=N

	Start up to N counting semaphore thrashing threads, where N is at most
	20. All will try and thrash the same semaphore.

 (*) ism=M

	Initialise the counting semaphore with M, where M is any positive
	integer greater than zero. The default is 4.

 (*) rd=N
 (*) wr=O
 (*) dg=P

	Start up to N reader thrashing threads, O writer thrashing threads and
	P downgrader thrashing threads, where N, O and P are at most 20
	apiece. All will try and thrash the same read/write semaphore.

 (*) elapse=N

	Run the tests for N seconds. The default is 5.

 (*) load=N

	Each thread delays for N uS whilst holding the lock. The dfault is 0.

 (*) interval=N

	Each thread delays for N uS whilst not holding the lock. The default
	is 0.

 (*) do_sched=1

	Each thread will call schedule if required after each iteration.

 (*) v=1

	Print more verbose information, including a thread iteration
	distribution list.

The module should be enabled by turning on CONFIG_DEBUG_SYNCHRO_TEST to "m".

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>