https://savvinov.com/2015/12/21/non-intrusive-tracing/
https://mahmoudhatem.wordpress.com/2016/01/11/combining-sql-trace-systemtap-part1-no-more-cpu-double-counting-unaccounted-for-time/
https://mahmoudhatem.wordpress.com/2015/11/12/vsql_cs_statistics-return-no-rows-in-12c-its-time-to-trace-systemtap-tracing/
http://externaltable.blogspot.jp/2014/11/life-of-oracle-io-tracing-logical-and.html
http://externaltable.blogspot.jp/2014/09/systemtap-into-oracle-for-fun-and-profit.html