# debugging swiN: clock sio



## bv_arvind (Jan 14, 2013)

Hi,
top outpur during bootup has 
 13 root        1 -32    -     0K    16K *Giant 0   1:01 100.00% swi4: clock sio

This causes very slow bootup. I am not sure how to debug this further. How to find which device registered for the the clock interrupt ?
Thanks


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## cpm@ (Jan 14, 2013)

Please, follow this thread and post your case in the same mailing list.


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## bv_arvind (Jan 16, 2013)

The reply was not helpful as I am new to debugging. How using ktrace or dtrace going to help out "clock sio" issue I am facing ?


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## cpm@ (Jan 16, 2013)

Sorry for my short reply. But you need debug your CPU to see what happen. In case you want go ahead and help developers to investigate, need build in your kernel some debugging tools. 

To start, read Handbook Chapter 26 dedicated to Dynamic Tracing (Dtrace). More resources can be found in DTrace wiki.

You should report your captures to identify which functions are eating your CPU to freebsd-stable@freebsd.org


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## bv_arvind (Jan 16, 2013)

Hi,
Thanks for the comments. I am using FB7 and it supports only ktrace. Would that be enough to debug ?


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## cpm@ (Jan 16, 2013)

Quoting FreeBSD Security Information:


> Older releases are not maintained and users are strongly encouraged to upgrade to one of the supported releases...



FreeBSD 7-RELEASE estimated EOL dropping on 28 february 2013. Read more about End-of-Life (EOL) dates, here. Probably "swi4" issue, increase clock usage is eating most free CPU time, can be solved if you update your system.

ktr(4) allow tracing of a broad range of "interesting" kernel events, so you could use to get a handle on what happens, anyway I recommend you do a upgrade.


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