Re: [LTP] [PATCH] open_posix_testsuite: Don't use clock_settime() to reset a CPU-time Clock

[Gui Jianfeng <guijianfeng@cn.fujitsu.com>]

Gui Jianfeng wrote:
> This case is trying to set CPU-time clock(ID is returned by clock_getcpuclockid()) of
> a specific process by calling clock_settime(). But Linux kernel doesn't allow to reset
> a CPU-time clock of a specific process. Kernel returns -EPERM. So test fails.
> 
> In "IEEE Std 1003.1, 2004 Edition", It's said as following:
> If _POSIX_CPUTIME is defined, implementations shall support clock ID values obtained by
> invoking clock_getcpuclockid(), which represent the CPU-time clock of a given process.
> Implementations shall also support the special clockid_t value CLOCK_PROCESS_CPUTIME_ID,
> which represents the CPU-time clock of the calling process when invoking one of the 
> clock_*() or timer_*() functions. For these clock IDs, the values returned by 
> clock_gettime() and specified by clock_settime() represent the amount of execution time
> of the process associated with the clock. Changing the value of a CPU-time clock via
> clock_settime() shall have no effect on the behavior of the sporadic server scheduling
> policy. 
> 
> So the behaviour when changing the value of a CPU-time clock via clock_settime() is
> operating system specific. 
> 
> We may change the test progress to stop using clock_settime(). Now, We just make use
> of clock_gettime() instead to achieve the same test purpose.
> 
> Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>

Hi Garrett,

How do you think this fix?

Gui

> ---
>  .../interfaces/clock_getcpuclockid/2-1.c           |   67 ++++++++++----------
>  1 files changed, 33 insertions(+), 34 deletions(-)
> 
> diff --git a/testcases/open_posix_testsuite/conformance/interfaces/clock_getcpuclockid/2-1.c b/testcases/open_posix_testsuite/conformance/interfaces/clock_getcpuclockid/2-1.c
> index edeb397..52240df 100644
> --- a/testcases/open_posix_testsuite/conformance/interfaces/clock_getcpuclockid/2-1.c
> +++ b/testcases/open_posix_testsuite/conformance/interfaces/clock_getcpuclockid/2-1.c
> @@ -23,48 +23,47 @@ int main(int argc, char *argv[])
>          printf("_POSIX_CPUTIME unsupported\n");
>          return PTS_UNSUPPORTED;
>  #else
> -	unsigned long time_to_set;	
>  	clockid_t clockid_1, clockid_2;
>  	struct timespec tp1, tp2;
> +	int i;
>  
>  	if (sysconf(_SC_CPUTIME) == -1) {
>  		printf("_POSIX_CPUTIME unsupported\n");
>  		return PTS_UNSUPPORTED;
>  	}
>  
> -	if (clock_getcpuclockid(getpid(), &clockid_1) != 0) {
> -		printf("clock_getcpuclockid(getpid(), ) failed\n");
> -		return PTS_FAIL;
> -	}
> -	
> -	if (clock_getcpuclockid(0, &clockid_2) != 0) {
> -		printf("clock_getcpuclockid(0, ) failed\n");
> -		return PTS_FAIL;
> -	}
> +        for (i = 0; i < 10; i++) {
> +                if (clock_getcpuclockid(getpid(), &clockid_1) != 0) {
> +                        printf("clock_getcpuclockid(getpid(), ) failed\n");
> +                        return PTS_FAIL;
> +                }
>  
> -	/* Set clockid_1 as a random value from 1 sec to 10 sec */
> -	srand((unsigned long)time(NULL));
> -	time_to_set = rand() * 10.0 / RAND_MAX + 1;
> -	tp1.tv_sec = time_to_set;
> -	tp1.tv_nsec = 0;	 
> -	if (clock_settime(clockid_1, &tp1) != 0) {
> -		printf("clock_getcpuclockid() returned an invalid clockid_t: "
> -			"%d\n", clockid_1);
> -		return PTS_FAIL;
> -	}
> -	/* Get the time of clockid_2, should almost the same as clockid_1 */
> -	if (clock_gettime(clockid_2, &tp2) != 0) {
> -		printf("clock_getcpuclockid() returned an invalid clockid_t: "
> -			"%d\n", clockid_2);
> -		return PTS_FAIL;
> -	}
> -	if (tp1.tv_sec == tp2.tv_sec)	
> -	{
> -		printf("Test PASSED\n");
> -		return PTS_PASS;
> -	}
> -	printf("Test FAILED\n");
> -	return PTS_FAIL;
> -	
> +                if (clock_getcpuclockid(0, &clockid_2) != 0) {
> +                        printf("clock_getcpuclockid(0, ) failed\n");
> +                        return PTS_FAIL;
> +                }
> +
> +                /* Get the time of clockid_1 */
> +                if (clock_gettime(clockid_1, &tp1) != 0) {
> +                        printf("clock_getcpuclockid() returned an invalid clockid_t: "
> +                               "%d\n", clockid_1);
> +                        return PTS_FAIL;
> +                }
> +
> +                /* Get the time of clockid_2, should almost the same as clockid_1 */
> +                if (clock_gettime(clockid_2, &tp2) != 0) {
> +                        printf("clock_getcpuclockid() returned an invalid clockid_t: "
> +                               "%d\n", clockid_2);
> +                        return PTS_FAIL;
> +                }
> +
> +                if (tp1.tv_sec != tp2.tv_sec) {
> +                        printf("Test FAILED\n");
> +                        return PTS_FAIL;
> +                }
> +        }
> +
> +        printf("Test PASSED\n");
> +        return PTS_PASS;
>  #endif
>  }

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