Chris Wedgwood writes:
>> I am trying to figure out how to modify the kernel such that I can
>> keep track of when code inside the kernel is run. In other words, I
>> would like to insert a piece of code that gets called when there is
>> a transition from user mode to kernel mode and vice versa. I am
>> using a recent version of the 2.3 kernel.
>
>Under intel there are various msr that can count various events for
>ring 0 and ring 3 (you have two counters which you can configure). I
>guess you should be able to count ring 3 cycles vs ring 0 cycles.
I've written a tool, PerfWatcher, which iterates over all the interesting
counters and can be configured to observe ring3, ring0 , and ring3+ring0.
The code will need some modification to do exactly what you want, but may be
of general interest as well:
http://picasso.nmr.ucsf.edu/~dek/content_download.html
Dave
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Email: dek@cgl.ucsf.edu David Konerding WWW: http://picasso.ucsf.edu/~dek
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