[Backport v2.5-branch] tests/timer_api: Correct precision and fix correctness mistakes #32371
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Correct a bunch of precision/analysis errors in this test: * Test items weren't consistent about tick alignment and resetting of the timestamp, so put these steps into init_timer_data() and call that immediately before k_timer_start(). * Many items would calculate the initial timestamp AFTER k_timer_start(), leading to an extra (third!) point where the timer computation could alias by an extra tick. Always do this consistently before the timer is started (via init_timer-data()). * Tickless systems with high tick rates can easily advance the system uptime while the timer ISR is running, so the system can't expect perfect accuracy even there (this test was originally written for ticked systmes where the ISR was by definition happening "at the same time"). (Unfortunately our most popular high tick rate tickless system, nRF5, also has a clock that doesn't divide milliseconds exactly, so it had a special path through all these precision comparisons and avoided the bugs. We finally found it on a x86 HPET system with 10 kHz ticks.) * The interval validation was placing a minimum bound on the interval time but not a maximum (this mistake was what had hidden the failure to reset the timestamp mentioned above). Longer term, the millisecond precision math in these tests is at this point an out of control complexity explosion. We should look at reworking the core OS tests of k_timer to use tick precision (which is by definition exact) pervasively and leave the millisecond stuff to a separate layer testing the alternative/legacy APIs. Fixes #31964 (probably -- that was reported against up_squared, on which I had trouble reproducing, but it was a common failure on ehl_crb). Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
nashif
approved these changes
Feb 16, 2021
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Backport
c2339db99622c1cb889cacd3133ade0413d11f6a~1..c2339db99622c1cb889cacd3133ade0413d11f6afrom #32277