Various options can be used for scaling and cropping.  Note
that \textwidth and \columnwidth can be your friends for such
operations -- most often, \columnwidth.

\includegraphics[clip,width=\columnwidth]{ols2003-ipsec-fig-input}
\includegraphics[scale=0.9]{scsi-ds}
\includegraphics[clip,height=3.0in]{relayarch}
\includegraphics[width=2cm]{tpch-host-based-component}
\includegraphics[width=\linewidth]{tpcw-component}
\includegraphics{efi-fig5}

This one uses 90 percent of the column width:
\includegraphics[width=0.9\columnwidth]{rmap_shadow_pages}