problems coding a real-time process

lockhart at irtf.ifa.hawaii.edu lockhart at irtf.ifa.hawaii.edu
Tue Jan 22 21:20:36 PST 2002


Ah, thanks, now could you direct me to the URL for the site that'll make
me not be retarded?  It's funny how if a routine returns -1 on failure and
0 on success, and you take that routine, and do a

if(!damn_routine_that_returns_0_on_success())
{
    gee_wont_it_always_do_this();
}

will just make you feel stupid from 6am to 11am in the morning on a
Tuesday.

So, on with the show, I *seem* to be able to set the scheduling policy for
my process, and set the rt_priority for the task.  I'm assuming this now
makes the process a high-priority real-time process, does this sound true?
 Now the problem I'm having is while my program also seems to think it's
running with a rt_priority of 99 and a scheduling policy of SCHED_FIFO, I
can't tell this for sure.  I run my program, sit there and watch top
update, and the priority listed for my process is still bouncing around
between 16 and 18.  So I'm thinking top doesn't indicate the absolute
priority, maybe the rt_priority and the regular priority are indicated
seperately, maybe if a task has a defined rt_priority and scheduling
policy the priority is just ignored.

Does any of this sound likely?  Can anybody actually confirm this? 
Because I have an enquiring mind and I need to know.

-Charles 


> Below is a URL to Numeric Unix Error Messages. Maybe that will help.
> 
> Steve Anderson
> 
> #define ESPIPE 29 /* Illegal seek */ 
> You aren't allowed to seek on a pipe. Socket calls can also return this.
> 
> http://www.aplawrence.com/Unixart/errors.html



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