design: function-exit probes

[Maneesh Soni]

On Mon, Feb 14, 2005 at 09:01:38AM -0800, Jim Keniston wrote:
[..]
> maxactive is specified by the user.  It is the number of instances of the
> probed function that can be active concurrently.  For example, if the
> function is non-recusrive and is called with a spinlock or mutex held,
> maxactive = 1 should be enough.  If the function never sleeps and is
> not recursive, NR_CPUS should be enough. (Right?)  maxactive is used to

If I am not wrong, here we should keep kernel premption also in mind. So,
in addition to above conditions, maxactive will be NR_CPUS when premption
is disabled.

> 
> 1.5	Assumptions and Limitations
> 
> 1.  This requires a probepoint (but not necessarily a user-defined
> handler) at the entry to every function whose returns are traced.

I think we need to take care for the case when user explicitly
wants to probe function entry point. I am not sure if kprobe
handles two probe handler for the same address.


Thanks
Maneesh

-- 
Maneesh Soni
Linux Technology Center, 
IBM India Software Labs,
Bangalore, India
email: maneesh@in.ibm.com
Phone: 91-80-25044990