lkml.org 
[lkml]   [2000]   [Sep]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectBehaviour of a cyclic task with HZ = 1024
Hi,

I have set the HZ constant to 1024 to increase the select resulution.
But the results of my measurements are not
as expected. I have a cyclical task (using select for timing) that
inverts a parallel port bit in each
cycle. I measure the high time with an oszillograph.

Here are my results:

15ms cycle: Everything as expected. The jitter is around 1ms
(corresponds to the 1000Hz).
10ms cycle: The cycle is either 10ms or 20ms. No values between.
5ms cycle: The cycle is either 10ms or 15ms. No values between.

Do you have any explanations for this behaviour? Is there a better way
to increase to resolution of the select call? Do I have to modify any
parameters in the scheduler code?

Peter

P.S: I found that the HZ constant is used in the tcp code. Do I have to
expect any errors coming from the changed HZ value?



-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:38    [W:0.024 / U:0.368 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site