My first experience with the Vampir trace visualiser was in 2010 during my studies at EPCC. While working on the exercises and samples, I was excited by the possibility of finding out what every process or thread (from thousands) is doing at any point in time. Over the years I have used TAU + Score-P + Vampir toolset with different applications on various systems. When it comes to trace visualisation for scientific applications at scale, Vampir is very impressive. If you haven't used it before, give a try!