Choosing a tracer

Kernel tracer Use the kernel tracer if you are debugging a system-wide performance problem or a kernel problem. This tracer comes with an instrumentation patch for most kernel subsystems, which is enough to debug many problems. This includes system calls, IRQs, traps, memory management, softIRQs, scheduling and many others. Of course, the kernel tracer allows you to add your own instrumentation anywhere in the kernel code. (Go to the kernel tracer site)

Userspace tracer Choose the userspace tracer if you want precise information about userspace activity. You can add UST instrumentation points in any userspace code. This includes libraries­. (Go to the userspace tracer site)

Combined tracing Both tracers can be used in combination to get events both from the kernel and from userspace, for complete system tracing. For this mode, install the two tracers.