Add section on Atomic traits

Author: PaulGannay

courses/02_intermediate/main.tex

@@ -798,8 +798,9 @@ \section{Atomics}
             \end{minted}
         \end{column}
         \begin{column}{0.5\linewidth}
-        \begin{itemize}
-          \item Either:
+          \noindent Either:
+
+          \vspace{0.5em}
           \SetTblrInner{rowsep=0pt}
           \begin{tblr}{colspec={cccc},rowspec={Q[lightmain]Q[white]Q[thread1]Q[thread6]}}
             \textbf{Thread 1} & \textbf{Thread 6} &  & \textbf{res} \\
@@ -809,7 +810,11 @@ \section{Atomics}
             &  &  & 7 \\
           \end{tblr}
           \pause
-        \item Or:
+          \vspace{0.5em}
+
+          \noindent Or: 
+
+          \vspace{0.5em}
           \SetTblrInner{rowsep=0pt}
           \begin{tblr}{colspec={cccc},rowspec={Q[lightmain]Q[white]Q[thread6]Q[thread1]}}
             \textbf{Thread 1} & \textbf{Thread 6} &  & \textbf{res} \\
@@ -818,7 +823,6 @@ \section{Atomics}
             atomic add & & ←→ & 7 \\
             &  &  & 7 \\
           \end{tblr}
-        \end{itemize}
         \end{column}
     \end{columns}
 \end{frame}
@@ -851,6 +855,33 @@ \section{Atomics}
   \end{columns}
 \end{frame}
 
+\begin{frame}[fragile]{Atomic Memory Trait}
+  \begin{columns}
+    \begin{column}{0.50\linewidth}
+      \begin{itemize}
+        \item If you need to access a View exclusively through atomic operation, you
+          can also create an alias for this View with the \texttt{Atomic} \texttt{MemoryTraits}
+        \item It guaranties that any operation done through the alias are done atomically
+      \end{itemize}
+    \end{column}
+    \begin{column}{0.50\linewidth}
+      \begin{minted}{C++}
+        Kokkos::View<double*> histo(5);
+        Kokkos::deep_copy(histo, 0);
+
+        View<int*, MemoryTraits<Atomic>> 
+          histo_atomic = histo;
+
+        Kokkos::parallel_for(
+          Kokkos::RangePolicy(0,N),
+          KOKKOS_LAMBDA(int i) {
+            histo_atomic(i%5) += i;
+          });
+      \end{minted}
+    \end{column}
+  \end{columns}
+\end{frame}
+
 \begin{frame}[fragile]{Performances}
   \begin{columns}
     \begin{column}{0.45\linewidth}
@@ -862,15 +893,16 @@ \section{Atomics}
     \end{itemize}
     \end{column}
     \begin{column}{0.55\linewidth}
-      \begin{exampleblock}{\vspace*{-3ex}}
+      \begin{block}
+        {\vspace*{-3ex}} % hide the title box of the block
         \begin{itemize}
           \item Atomics should be used with care and only when strictly
             necessary
           \item Algorithm can sometime be changed when porting from CPU to GPU
             in order to remove the need for atomics (colouring, replacing in
             place algorithm with out of place algorithm,~…)
         \end{itemize}
-      \end{exampleblock}
+      \end{block}
     \end{column}
   \end{columns}
 \end{frame}