timestuff, was Re: performance, was Re: [LinuxPPS] patch report

[Rodolfo Giometti]

On Tue, Jul 18, 2006 at 02:23:54PM -0700, gnu not unix wrote:
> 
> Also, the timestamp in linuxpps_event occurs *after*
> a couple of "if" tests. I'm a bit skeptical about that,
> and I'm thinking of moving the gettimeofday to before
> the two if tests. No harm in doing it there, after all.
> I do exactly that in the shm parallel port pps driver
> code, just grab a timestamp and ignore it if needs be.

Did you mean something like this?

   diff --git a/drivers/pps/kapi.c b/drivers/pps/kapi.c
   index 71177bd..a225ebf 100644
   --- a/drivers/pps/kapi.c
   +++ b/drivers/pps/kapi.c
   @@ -120,7 +120,11 @@ void linuxpps_event(int source, int even
    {
    	struct timespec ts;
    
   -	/* Sanity checks */
   +	/* First of all we get the time stamp... */
   +	do_gettimeofday((struct timeval *) &ts);
   +	ts.tv_nsec *= 1000;	  /* microseconds to nanoseconds */
   +
   +	/* ... then we can do some sanity checks */
    	if (!linuxpps_is_allocated(source)) {
    		err("unknow source for event!");
    		return;
   @@ -130,10 +134,6 @@ void linuxpps_event(int source, int even
    		return;
    	}
    
   -	/* Get the time stamp */
   -	do_gettimeofday((struct timeval *) &ts);
   -	ts.tv_nsec *= 1000;	  /* microseconds to nanoseconds */
   -
    	/* Must call the echo function? */
    	if ((linuxpps_source[source].params.mode&(PPS_ECHOASSERT|PPS_ECHOCLEAR)) != 0)
    		linuxpps_source[source].info->echo(source, event);
      
Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti at enneenne.com
Linux Device Driver                             giometti at gnudd.com
Embedded Systems                     		giometti at linux.it
UNIX programming                     phone:     +39 349 2432127
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