Take measurements of 't0' and 'ref_time' after enable_counters(), so
that they only measure the time consumed when the counters are enabled.
Signed-off-by: NSong Liu <songliubraving@fb.com>
Acked-by: NAndi Kleen <andi@firstfloor.org>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Cc: kernel-team@fb.com
Link: http://lore.kernel.org/lkml/20210316211837.910506-3-songliubraving@fb.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>