Re: [LTP] [PATCH][realtime] prio-wake: allow for optional locking prior to broadcast

[Subrata Modak <subrata@linux.vnet.ibm.com>]

On Mon, 2009-08-24 at 15:14 -0700, Darren Hart wrote: 
> prio-wake: allow for optional locking prior to broadcast
> 
> Allow the user to decide if the mutex should be held prior to
> calling pthread_cond_broadcast().  Default remains the same.
> Tested with and without the argument as well as with both 0 and 1
> passed to the argument. Values other than 0 and 1 will result in locking
> the mutex.
> 
> Signed-off-by: Darren Hart <dvhltc@us.ibm.com>

Thanks.

Regards--
Subrata

> Acked-By: Dinakar Guniguntala <dino@in.ibm.com>
> Acked-by: Vernon Mauery <vernux@us.ibm.com>
> Acked-by: Gowrishankar <gowrishankar.m@in.ibm.com>
> 
> ---
>  func/prio-wake/prio-wake.c |   18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> Index: realtime/func/prio-wake/prio-wake.c
> ===================================================================
> --- realtime.orig/func/prio-wake/prio-wake.c
> +++ realtime/func/prio-wake/prio-wake.c
> @@ -56,6 +56,7 @@
>  #include <librttest.h>
>  volatile int running_threads = 0;
>  static int rt_threads = 0;
> +static int locked_broadcast = 1;
>  static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
>  static pthread_mutex_t mutex;
>  static volatile nsec_t beginrun;
> @@ -67,6 +68,8 @@ void usage(void)
>          rt_help();
>          printf("prio-wake specific options:\n");
>          printf("  -n#           #: number of worker threads\n");
> +        printf("  -l#           1:lock the mutex before broadcast, 0:don't\n");
> +	printf("                defaults to 1\n");
>  }
> 
>  int parse_args(int c, char *v)
> @@ -80,6 +83,9 @@ int parse_args(int c, char *v)
>                  case 'n':
>                          rt_threads = atoi(v);
>                          break;
> +                case 'l':
> +                        locked_broadcast = atoi(v);
> +                        break;
>                  default:
>                          handled = 0;
>                          break;
> @@ -106,9 +112,11 @@ void *master_thread(void* arg)
> 
>  	printf("%08lld us: Master thread about to wake the workers\n", start/NS_PER_US);
>  	/* start the children threads */
> -	rc = pthread_mutex_lock(&mutex);
> +	if (locked_broadcast)
> +		rc = pthread_mutex_lock(&mutex);
>  	rc = pthread_cond_broadcast(&cond);
> -	rc = pthread_mutex_unlock(&mutex);
> +	if (locked_broadcast)
> +		rc = pthread_mutex_unlock(&mutex);
> 
>  	while (running_threads > 0)
>  		sleep(1);
> @@ -161,7 +169,7 @@ int main(int argc, char* argv[])
>  	int i;
>  	setup();
> 
> -        rt_init("hn:", parse_args, argc, argv);
> +        rt_init("hn:l:", parse_args, argc, argv);
> 
>  	if (rt_threads == 0) {
>  		numcpus = sysconf(_SC_NPROCESSORS_ONLN);
> @@ -172,7 +180,9 @@ int main(int argc, char* argv[])
>  	printf("\n-----------------------\n");
>  	printf("Priority Ordered Wakeup\n");
>  	printf("-----------------------\n");
> -	printf("Worker Threads: %d\n\n", rt_threads);
> +	printf("Worker Threads: %d\n", rt_threads);
> +	printf("Calling pthread_cond_broadcast() with mutex: %s\n\n",
> +	       locked_broadcast ? "LOCKED" : "UNLOCKED");
> 
>  	pri_boost = 3;
> 


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