Adding diff command the flexibility to specify multiple data files on input. If not input file is given the standard behaviour stands and diff inspects 'perf.data' and 'perf.data.old' files. Signed-off-by: Jiri Olsa <jolsa@redhat.com> Reviewed-by: Namhyung Kim <namhyung@kernel.org> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-8j3xer54ltvs76t0fh01gcvu@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>