%ToDo: Shall we add the unrolling of projection-loop in parameters?
\begin{table}[htb] %[htbp]
\begin{threeparttable}
\caption{\label{tbl:newtex} Performance and configuration of cache-aware texture-based back-projection kernel}
\centering
\noindent
%\resizebox{\columnwidth}{!}{\begin{tabular}{} ... \end{\tabular}}
\begin{tabularx}{\columnwidth}{ | X  c | r | r r r | }
\hline
& & & \multicolumn{3}{c|}{Configuration} \\
\mhd{|c}{GPU} & \mhd{c|}{$n_v$} & \mhd{c|}{Perf.} & \mhd{c}{Occupancy} & \mhd{c}{L1/ShMem} & \mhd{c|}{Cache} \\

\hline
GTX295 & 1 &  49 GU/s & 75\% & - & -  \\

\hline
\multirow{3}{*}{GTX580} 
& 1 &  49 GU/s & 50\% & 16/48 & -  \\
& 2 &  97 GU/s & 50\% & 16/48 & -  \\
& 4 & 172 GU/s & 50\% & 16/48 & -  \\
\hline

\multirow{3}{*}{GTX680} 
& 1 & 118 GU/s & 100\% & 16/48 & - \\
& 2 & 232 GU/s & 100\% & 32/32 & - \\ 
\hline

\multirow{3}{*}{Titan} 
& 1 & 200 GU/s & 100\% & 16/48 & -  \\
& 2 & 362 GU/s & 100\% & 32/32 & - \\
\hline

\multirow{3}{*}{GTX980} 
& 1 & 155 GU/s & 100\% & -     & - \\
& 2 & 304 GU/s & 100\% & -     & - \\
& 4 & 555 GU/s &  75\% & -     & - \\
\hline

\multirow{3}{*}{Titan X} 
& 1 & 389 GU/s & 100\% & -     & - \\
& 2 & 726 GU/s & 100\% & -     & - \\
& 4 &1396 GU/s &  75\% & -     & - \\
\hline

HD5970 & 1 &  56 GU/s & - & - & 256 \\
\hline
HD7970 & 1 & 115 GU/s & - & - & 256 \\
\hline
R9-290 & 1 & 146 GU/s & - & - & 256 \\
\hline
\end{tabularx}
\begin{tablenotes}
\item The table summarizes the performance and optimal configuration for the texture-based back-projection kernel. Information is provided for all supported slice-modes.
\end{tablenotes}
\end{threeparttable}
\end{table}
