\section{Architecture of current GPUs}
-The architecture \index{architecture of a GPU} of current GPUs is constantly
+The architecture \index{GPU!architecture of a} of current GPUs is constantly
evolving. Nevertheless some trends remain constant throughout this evolution.
Processing units composing a GPU are far simpler than a traditional CPU and
it is much easier to integrate many computing units inside a GPU card than to do
\section{Memory hierarchy}
-The memory hierarchy of GPUs\index{memory~hierarchy} is different from that of CPUs. In practice, there are registers\index{memory~hierarchy!registers}, local
-memory\index{memory~hierarchy!local~memory}, shared
-memory\index{memory~hierarchy!shared~memory}, cache
-memory\index{memory~hierarchy!cache~memory}, and global
-memory\index{memory~hierarchy!global~memory}.
+The memory hierarchy of GPUs\index{memory hierarchy} is different from that of CPUs. In practice, there are registers\index{memory hierarchy!registers}, local
+memory\index{memory hierarchy!local memory}, shared
+memory\index{memory hierarchy!shared memory}, cache
+memory\index{memory hierarchy!cache memory}, and global
+memory\index{memory hierarchy!global memory}.
As previously mentioned each thread can access its own registers. It is
