Explain what tracepoint profiling sources are about.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Jeff Garzik <jeff@garzik.org>
LKML-Reference: <1248856508.6987.3041.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>