28 lines
1.3 KiB
Plaintext
28 lines
1.3 KiB
Plaintext
Title: Timer Starvation test
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The purpose of the test is to detect whether the timer implementation
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correctly handles situations where only one timeout is present, and that
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timeout is repeatedly rescheduled before it has a chance to fire. In
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some implementations this may prevent the timer interrupt handler from
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ever being invoked, which in turn prevents an announcement of ticks.
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Lack of tick announcement propagates into a monotonic increase in the
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value returned by z_clock_elapsed().
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This test is not run in automatic test suites because it generally takes
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minutes, hours, or days to fail, depending on the hardware clock rate
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and the tick rate. By default the test passes if one hour passes
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without detecting a failure.
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Failure will occur when some counter wraps around. This may be a
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hardware timer counter, a timer driver internal calculation of
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unannounced cycles, or the Zephyr measurement of unannounced ticks.
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For example a system that uses a 32768-Hz internal timer counter with
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24-bit resolution and determines elapsed time by a 24-bit unsigned
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difference between the current and last-recorded counter value will fail
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at 512 s when the updated counter value is observed to be less than the
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last recorded counter.
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Systems that use a 32-bit counter of 80 MHz ticks would fail after
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53.687 s.
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