samples files are lazilly created when the first
sample comes from a binary image, but op_time show
than many time empty samples files exist. It's seems
to be a daemon problem or a libdb problem, dumping
the samples files shows it is really empty (root page
is nil, no info entry exist with a count != 0).
I've tried to track the bug but found nothing which
seems bad, verbose oprofiled show an incoming sample,
the samples file is created, sample would be stored but
samples file remains empty.
a simple oprof_start and op_stop after a few second
demonstrate the problem.