[asterisk-bugs] [Asterisk 0005492]: 2.6 driver assumes 1000 HZ clock

[noreply at bugs.digium.com]

A NOTE has been added to this issue. 
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http://bugs.digium.com/view.php?id=5492 
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Reported By:                yow
Assigned To:                
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Project:                    Asterisk
Issue ID:                   5492
Category:                   Core/General
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     closed
Asterisk Version:           I did not set the version :( 
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Disclaimer on File?:        N/A 
Request Review:              
Resolution:                 open
Fixed in Version:           
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Date Submitted:             10-21-2005 13:55 CDT
Last Modified:              06-07-2008 11:05 CDT
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Summary:                    2.6 driver assumes 1000 HZ clock
Description: 
You just schedule for the next jiffy. That does not ensure that
you will get a 1 kHz timing for ztdummy. The non-dummy drivers
can also be unreliable if you depend on precise timing.

For most architectures, Linux now offers 3 choices:

100 HZ, 250 HZ, 1000 HZ

The default is now 250 HZ, because 1000 HZ is unreliable. The BIOS may
grab the CPU for a long time via the SMI (System Management Interrupt)
and SMM (System Management Mode). While the problem is most common and
severe on laptops, it is also commonly seen on high-end servers.

Basically, you shouldn't rely on a 1 kHz tick working for all hardware.

You especially shouldn't expect this from the system's clock tick.

(BTW, this would have been fixed if the driver shipped with the rest of
the kernel; people regularly scan the source tree for such errors)

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---------------------------------------------------------------------- 
 svnbot - 06-07-08 11:05  
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Repository: dahdi
Revision: 796

U   trunk/ztdummy.c

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r796 | markster | 2008-06-07 11:05:39 -0500 (Sat, 07 Jun 2008) | 2 lines

Error out on ztdummy if 1000hz is not used (bug
http://bugs.digium.com/view.php?id=5492)

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http://svn.digium.com/view/dahdi?view=rev&revision=796 

Issue History 
Date Modified   Username       Field                    Change               
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06-07-08 11:05  svnbot         Checkin                                      
06-07-08 11:05  svnbot         Note Added: 0088076                          
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