  The mixed-size placement benchmarks described in this book chapter directly
address several of the shortcomings in previously published suboptimality
benchmarks. Two new sets of placement examples are constructed, one targeting
the role of nonlocal nets in suboptimality, and another targeting the role of
white space and large variations in module sizes. The first set, PEKO-MC, is a
set of standard-cell circuits with nonlocal nets in known optimal placements. A
given netlist is modified so as to render a given placement for it optimal for
the new netlist. Cell dimensions and locations are not changed, net-degree
statistics are matched exactly, and over 60% of the original netlist is left
unchanged. The second set, PEKO-MS, incorporates a parametrized percentage of
white space into a mixed-size placement which precisely matches given macro
dimensions and locations as well as the net-degree distributions of the ISPD
2005 benchmark suite [21]. HPWL for the placements generated for the PEKO-MS
circuits are proven to be less than 3% above optimal for most cases and within
8% of optimal on all cases.
