Re: [PATCH i-g-t 1/3] lib/igt_aux: Export statistics of signal helper.

[Mika Kahola <mika.kahola@intel.com>]

On Wed, 2017-08-02 at 12:29 +0200, Maarten Lankhorst wrote:
> Export 2 functions, igt_signal_helper_get_num and
> igt_signal_helper_get_hz.
> 
> This will allow tests to measure how much time in a test was spent
> in a uninterruptible state, which is useful when testing whether
> certain ioctl's can be interrupted or not.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> ---
>  lib/igt_aux.c | 30 +++++++++++++++++++++++++++---
>  lib/igt_aux.h |  2 ++
>  2 files changed, 29 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/igt_aux.c b/lib/igt_aux.c
> index 86a213c2032f..265e43f399e7 100644
> --- a/lib/igt_aux.c
> +++ b/lib/igt_aux.c
> @@ -275,7 +275,7 @@ bool __igt_sigiter_continue(struct __igt_sigiter
> *iter, bool enable)
>  }
>  
>  static struct igt_helper_process signal_helper;
> -long long int sig_stat;
> +static int64_t sig_stat;
>  static void __attribute__((noreturn)) signal_helper_process(pid_t
> pid)
>  {
>  	/* Interrupt the parent process at 500Hz, just to be
> annoying */
> @@ -314,6 +314,9 @@ void igt_fork_signal_helper(void)
>  	if (igt_only_list_subtests())
>  		return;
>  
> +	/* Reset number of signalscaught */
> +	sig_stat = 0;
> +
>  	/* We pick SIGCONT as it is a "safe" signal - if we send
> SIGCONT to
>  	 * an unexpecting process it spuriously wakes up and does
> nothing.
>  	 * Most other signals (e.g. SIGUSR1) cause the process to
> die if they
> @@ -348,8 +351,29 @@ void igt_stop_signal_helper(void)
>  		return;
>  
>  	igt_stop_helper(&signal_helper);
> +}
>  
> -	sig_stat = 0;
> +/**
> + * igt_signal_helper_get_num:
> + *
> + * Return the amount of signals generated since the last time
> + * igt_fork_signal_helper() was called.
> + *
> + * This is reset to 0 on every call to igt_fork_signal_helper.
> + */
> +int64_t igt_signal_helper_get_num(void)
> +{
> +	return sig_stat;
> +}
> +
> +/**
> + * igt_signal_helper_get_hz:
> + *
> + * Return the approximate amount of signals generated per second.
> + */
> +int igt_signal_helper_get_hz(void)
> +{
> +	return 50;
>  }
I wonder if this is really necessary? The function returns hardcoded
value and it is only used in one place i.e. third patch of this series.
>  
>  static struct igt_helper_process shrink_helper;
> @@ -357,7 +381,7 @@ static void __attribute__((noreturn))
> shrink_helper_process(int fd, pid_t pid)
>  {
>  	while (1) {
>  		igt_drop_caches_set(fd, DROP_SHRINK_ALL);
> -		usleep(1000 * 1000 / 50);
> +		usleep(1000 * 1000 / igt_signal_helper_get_hz());
>  		if (kill(pid, 0)) /* Parent has died, so must we. */
>  			exit(0);
>  	}
> diff --git a/lib/igt_aux.h b/lib/igt_aux.h
> index 499a16796ebb..7e080089dcbc 100644
> --- a/lib/igt_aux.h
> +++ b/lib/igt_aux.h
> @@ -55,6 +55,8 @@ extern int num_trash_bos;
>  /* generally useful helpers */
>  void igt_fork_signal_helper(void);
>  void igt_stop_signal_helper(void);
> +int64_t igt_signal_helper_get_num(void);
> +int igt_signal_helper_get_hz(void);
>  
>  void igt_fork_shrink_helper(int fd);
>  void igt_stop_shrink_helper(void);
-- 
Mika Kahola - Intel OTC

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