David
How are you setting the frequency/period of the task/thread that
sets the signal?
Norm
> -----Original Message-----
> From: [EMAIL PROTECTED] [SMTP:[EMAIL PROTECTED]]
> Sent: Tuesday, October 16, 2001 4:46 AM
> To: 'Norm Dresner'
> Cc: '[EMAIL PROTECTED]'
> Subject: RE: [rtl] Maximum cycling frequency of 200Hz?
>
> Norm,
> I'm running a test program. There are two threads.
> One is just to generate clock events for the other.
>
> So the first thread is set up as periodic with a time interval x and then
> just loops...
> while (1)
> {
> pthread_wait_np();
> semaphore->signal();
> }
>
> The second thread waits on the semaphore, and counts the clock events
> until
> 1 second passes (i.e. 1/x counts) and prints actual time.
>
> Therefore, I expect to see print messages of the actual time every 1
> second.
>
> This works fine for x = 10msec, and x = 5msec.
> But at x = 4msec (count = 250), the time interval in the print message is
> ~1.25secs (i.e. 250*5msec), and at x = 2msec (count = 500), the time
> interval is 2.5secs (i.e. 500*5msec).
>
> Therefore, I deduce that the smallest period I can set is 5msec (loading
> of
> the processor is not a factor as all I do is increment a number each
> cycle).
>
> So, how do others achieve higher rates? From what I read, I get the
> impression that I have to recompile the kernel with
> #define HZ 1000
> in params.h file.
>
> Is this correct?
> David
>
> -----Original Message-----
> From: Norm Dresner [mailto:[EMAIL PROTECTED]]
> Sent: 15 October 2001 19:46
> To: [EMAIL PROTECTED]
> Cc: [EMAIL PROTECTED]
> Subject: Re: [rtl] Maximum cycling frequency of 200Hz?
>
>
> I've been running 1300 Hz on P-133 and PMMX-233 for
> billions of cycles with no observed deviation from the
> programmed frequency. On the P-133, my RT-kernel code
> takes about 40% of my CPU's bandwidth but it seems to be
> less than 10% on the PMMX-233. What do you have your
> thread doing?
>
> Norm
>
> ----- Original Message -----
> From: David Hamilton <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Monday, October 15, 2001 5:44 AM
> Subject: [rtl] Maximum cycling frequency of 200Hz?
>
>
> > I'm running RTLinux 3.1 on a PC with an AMD K6 500Mhz
> processor (RedHat7.1).
> >
> > I seem to be only able to run a real-time loop at a
> maximum frequency of
> > 200Hz.
> > Trying to set a lower period in pthread_make_period... or
> a shorter sleep in
> > nanosleep has no effect beyond 200Hz (5msec)!
> >
> > I've read in other emails about the #define HZ 100 in the
> linux param.h
> > file, but assumed that only effected context switching
> within the user
> > space.
> > I've also read about people reaching rates in excess of
> 1KHz (I'm looking
> > for 1KHz).
> >
> > Can anyone tell me what I have to do to get these higher
> frequencies, or is
> > it a limitation of my hardware.
> > David
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> >
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