%         Registration             Locating system problems using dynamic     
%                                             instrumentation                 
%                              Vara Prasad (varap@us.ibm.com)                 

It is often difficult to diagnose complex      
problems without multiple rebuilds and         
reboots. Even in a simple setup, the problem   
can touch various layers of the application    
and operating system. Diagnosis is even more   
difficult in complex, multi-tiered systems. As 
Linux is deployed in these environments, it is 
becoming more important to have facilities to  
locate and identify such problems.             

Using the kprobes infrastructure, SystemTAP is 
being developed to dynamically instrument the  
kernel and user applications. SystemTAP        
instrumentation incurs low overhead when       
enabled, and zero overhead when disabled.      
SystemTAP provides facilities to define        
instrumentation points in a high-level         
language, and to aggregate and analyze the     
instrumentation data. Details of the SystemTAP 
architecture and implementation are presented, 
along with examples of solving problems in the 
production environments.