dtrace

syscall::clock_gettime:return
/ !self->bs_guard && !self->in_bm && execname == willrun /
{
 bss = vtimestamp;
 self->bs_guard = 0;
 self->in_bm = 1;
}

syscall::clock_gettime:entry
/ !self->bs_guard && self->in_bm && execname == willrun /
{
 this->time = (vtimestamp - bss);
 @bs_count = count();
 @bs_sum = sum(this->time / 1000);
 @bs_avg = avg(this->time);
 self->bs_guard = 1;
 self->in_bm = 0;
}

syscall::clock_gettime:return
/ self->bs_guard && !self->in_bm && execname == willrun /
{
 self->bs_guard = 0;
 self->bs_bm = 0;
}