Re: misc/49342: [test] lib/libc/gen/t_time.c is non-deterministic; compares set time vs current time (and can vary by a second under rare circumstances)

To: gnats-bugs%netbsd.org@localhost
Subject: Re: misc/49342: [test] lib/libc/gen/t_time.c is non-deterministic; compares set time vs current time (and can vary by a second under rare circumstances)
From: Justin Cormack <justin%specialbusservice.com@localhost>
Date: Thu, 30 Oct 2014 22:45:48 +0000

On Thu, Oct 30, 2014 at 10:05 PM,  <yaneurabeya%gmail.com@localhost> wrote:
> The lib/libc/gen/t_time:time_timeofday testcase works in most cases, but
> if the clock rolls over between when time and gettimeofday are called, the value returned from time and the tv_sec value can vary between, as noted in one of our Kyua runs on FreeBSD:
>
> Test case: lib/libc/gen/t_time:time_timeofday

> The testcase should have "fuzzing" built in so it allows for a maximum of 1 second difference between the two compared values.

It could be worse than 1s, worst case, as this is not a monotonic
clock, and in either direction, in theory. Not a very good test, but I
suppose if we change to 10s wither way its fairly safe...

Justin

References:
- misc/49342: [test] lib/libc/gen/t_time.c is non-deterministic; compares set time vs current time (and can vary by a second under rare circumstances)
  - From: yaneurabeya

Home | Main Index | Thread Index | Old Index