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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 01/05/14 at 17:17:08

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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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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