Re: [ANNOUNCE] rt-tests-2.0

On Mon, 28 Jun 2021, Daniel Wagner wrote:

Hi Mike,

On Sat, Jun 26, 2021 at 02:45:27PM +0200, Mike Galbraith wrote:

quoted

On Sat, 2021-06-26 at 13:47 +0200, Mike Galbraith wrote:

quoted

On Sat, 2021-06-26 at 08:55 +0200, Mike Galbraith wrote:

quoted

On Fri, 2021-06-25 at 12:08 -0400, John Kacur wrote:

quoted

I'm pleased to announce rt-tests-2.0

Greetings,

cyclictest seems to have grown an mlock related regression.

Ok, chores done, I did a quick bisect/confirm.  I didn't go stare
at rt_test_start() to ponder what the mlockall connection may be.

Moving the call above "Get current time" stops it mucking things up.

Thanks a lot for your excellent report. rt_test_start does

  static char ts_start[MAX_TS_SIZE];

  static void get_timestamp(char *tsbuf)
  {
          struct timeval tv;
          struct tm *tm;
          time_t t;

          gettimeofday(&tv, NULL);
          t = tv.tv_sec;
          tm = localtime(&t);
          /* RFC 2822-compliant date format */
          strftime(tsbuf, MAX_TS_SIZE, "%a, %d %b %Y %T %z", tm);
  }

  void rt_test_start(void)
  {
          get_timestamp(ts_start);
  }

I'd say the tsbuf access is the one which triggers a pagefault.

John, I would suggest to move the rt_test_start() into rt_init() and
take the timestamp at the execution start (as my initial version was). I
think the additional pain in slightly more correct start timestamp
(which is also not defined what it actually means in this context) is
just not worth the effort.

Thanks,
Daniel

Send me a patch, and I'll have a look. The timerthread()function is
sensitive anyway, so it's probably a good idea not to put that kind
of thing there.

Note that the the code following the /* Get Current Time */
is getting the time, but you probably want something rougher that
you can call strftime on?

John