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rhsemshuffle.adoc @ 564ce0f

4.115

Last change on this file since 564ce0f was b6c1578, checked in by Joel Sherrill <joel.sherrill@…>, on Jan 5, 2014 at 5:17:08 PM

rhealstone: Add rh prefix to all test names

This makes them easier to spot as a group in wildcard searches.

File size: 1.1 KB

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[19e9bf8]	1	= Semaphore Shuffle Benchmark
	2
	3	This benchmark measures the average delay between a task's release of a
	4	semaphore and the activation of another task blocked on that semaphore.
	5
	6	== Directives
	7
	8	* rtems_semaphore_obtain
	9	* rtems_semaphore_release
	10	* rtems_task_wake_after
	11
	12
	13	== Methodology
	14
	15	This benchmark has two equal priority tasks switch between themselves a total
	16	of BENCHMARKS * 2 times. This is timed, and then execute the same code but
	17	having the tasks pass a semphore between themselves. A task obtains the
	18	semphore, then yields to the other task, which blocks on the semaphore. The
	19	task owning the semaphore then releases it and yields. This process is
	20	repeated by the other task.
	21
	22	This benchmark has overhead, especially in the time it takes to switch between
	23	the two tasks, which happens a total of 2 times per semaphore shuffle. By first
	24	timing how long it takes the tasks to switch between themselves without any
	25	semaphore related calls, the overhead time is found. This time is then subtracted
	26	from the total time of the benchmark, with semaphore shuffling occuring.

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