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
> -- [rtl] ---
> To unsubscribe:
> echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR
> echo "unsubscribe rtl <Your_email>" | mail
[EMAIL PROTECTED]
> --
> For more information on Real-Time Linux see:
> http://www.rtlinux.org/
>
-- [rtl] ---
To unsubscribe:
echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR
echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED]
--
For more information on Real-Time Linux see:
http://www.rtlinux.org/
