UHD buffer high water mark

Hello,

I am running a B200 with UHD 3.15 at 50 MSPS with sc8 on the wire and
host format.  I use a device argument of "num_recv_frames=1024" in an
attempt to minimize the occurrence of overflows.  Is there a way of
knowing how many of these frames are filled before being read, something
like a high water mark to determine how close to overflow the code is
getting?

Thanks!