svn commit: r360033 - head/tests/sys/kqueue/libkqueue

[Ian Lepore]

On Fri, 2020-04-17 at 02:22 +0000, Kyle Evans wrote:
> Author: kevans
> Date: Fri Apr 17 02:22:15 2020
> New Revision: 360033
> URL: https://svnweb.freebsd.org/changeset/base/360033
> 
> Log:
>   tests: kqueue: use a more precise timer for the NOTE_ABSTIME test
>   
>   Originally noticed while attempting to run the kqueue tests under
>   qemu-user-static, this apparently just happens sometimes when running in a
>   jail in general -- the timer will fire off "too early," but it's really just
>   the result of imprecise measurements (noted by cem).
>   
>   Kicking this over to NOTE_USECONDS still tests the correct thing while
>   allowing it to work more consistently; a basic sanity test reveals that we
>   often end up coming in just less than 200 microseconds after the timer
>   fired off.
>   
>   MFC after:	3 days
> 
> Modified:
>   head/tests/sys/kqueue/libkqueue/timer.c
> 
> Modified: head/tests/sys/kqueue/libkqueue/timer.c
> ==============================================================================
> --- head/tests/sys/kqueue/libkqueue/timer.c	Fri Apr 17 02:21:46 2020	(r360032)
> +++ head/tests/sys/kqueue/libkqueue/timer.c	Fri Apr 17 02:22:15 2020	(r360033)
> @@ -216,17 +216,17 @@ test_abstime(void)
>  {
>      const char *test_id = "kevent(EVFILT_TIMER, EV_ONESHOT, NOTE_ABSTIME)";
>      struct kevent kev;
> -    time_t start;
> -    time_t stop;
> -    const int timeout = 3;
> +    long end, start, stop;
> +    const int timeout_sec = 3;
>  
>      test_begin(test_id);
>  
>      test_no_kevents();
>  
> -    start = time(NULL);
> +    start = now();
> +    end = start + SEC_TO_US(timeout_sec);
>      EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ONESHOT,
> -      NOTE_ABSTIME | NOTE_SECONDS, start + timeout, NULL);
> +      NOTE_ABSTIME | NOTE_USECONDS, end, NULL);
>      if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
>          err(1, "%s", test_id);
>  
> @@ -235,10 +235,10 @@ test_abstime(void)
>      kev.data = 1;
>      kev.fflags = 0;
>      kevent_cmp(&kev, kevent_get(kqfd));
> -    stop = time(NULL);
> -    if (stop < start + timeout)
> -        err(1, "too early %jd %jd", (intmax_t)stop, (intmax_t)(start + timeout));
>  
> +    stop = now();
> +    if (stop < end)
> +        err(1, "too early %jd %jd", (intmax_t)stop, (intmax_t)end);
>      /* Check if the event occurs again */
>      sleep(3);
>      test_no_kevents();

Not caused by you, but this change made me notice:  using 'long' to
hold the number of microseconds since the unix epoch will only work on
amd64 and arm64.  Everything involved with that needs to use uint64_t
to work on all arches.

-- Ian