[PATCH 2/2] Determine the iteration count based on wallclock instead of user+system time.

[Marcin Kościelnicki]

On 20/08/15 19:32, Wei-cheng Wang wrote:
> Hi Ulrich,
>
> This patch will combine with "Tracepoint for ppc64" into one patch.
> Is this ok?
>
> Thanks,
> Wei-cheng
>

This patch has been accepted half a year ago, and the author has 
disappeared.  It fixes the same underlying issue as my patch at 
https://sourceware.org/ml/gdb-patches/2016-01/msg00716.html .  Since 
this patch seems to be a smarter fix, I'd like to abandon mine, and go 
with that one instead.  I've just checked it - works just fine and fixes 
the problem on s390{,x}-ibm-linux-gnu, no regressions on 
x86_64-unknown-linx-gnu.

OK to push?

> ---
>
> gdb/testsuite/ChangeLog
>
> 2015-08-23  Wei-cheng Wang  <cole945@gmail.com>
>
> 	* gdb.trace/tspeed.c (myclock): Return wallclock instead of
> 	user+system time.
> 	(trace_speed_test): Determine the iteration count for a time
> 	between 15..30 seconds.
> ---
>   gdb/testsuite/gdb.trace/tspeed.c | 16 ++++++----------
>   1 file changed, 6 insertions(+), 10 deletions(-)
>
> diff --git a/gdb/testsuite/gdb.trace/tspeed.c b/gdb/testsuite/gdb.trace/tspeed.c
> index ca4c7bf..c9e212c 100644
> --- a/gdb/testsuite/gdb.trace/tspeed.c
> +++ b/gdb/testsuite/gdb.trace/tspeed.c
> @@ -56,13 +56,9 @@ int nspertp = 0;
>   unsigned long long
>   myclock ()
>   {
> -  struct timeval tm, tm2;
> -  struct rusage ru;
> -  getrusage (RUSAGE_SELF, &ru);
> -  tm = ru.ru_utime;
> -  tm2 = ru.ru_stime;
> -  return (((unsigned long long) tm.tv_sec) * 1000000) + tm.tv_usec
> -    + (((unsigned long long) tm2.tv_sec) * 1000000) + tm2.tv_usec;
> +  struct timeval tm;
> +  gettimeofday (&tm, NULL);
> +  return (((unsigned long long) tm.tv_sec) * 1000000) + tm.tv_usec;
>   }
>
>   int
> @@ -162,9 +158,9 @@ trace_speed_test (void)
>       return -1;
>
>     if (idelta > mindelta
> -      /* Total test time should be between 2 and 5 seconds.  */
> -      && (total1 + total2) > (2 * 1000000)
> -      && (total1 + total2) < (5 * 1000000))
> +      /* Total test time should be between 15 and 30 seconds.  */
> +      && (total1 + total2) > (15 * 1000000)
> +      && (total1 + total2) < (30 * 1000000))
>       {
>         nsdelta = (((unsigned long long) idelta) * 1000) / iters;
>         printf ("Second loop took %d ns longer per iter than first\n", nsdelta);
>