artiq/doc/slides/artiq_overview.tex

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\begin{document}
\fontseries{l}\selectfont

\title{ARTIQ}
\subtitle{A new control system for trapped ion experiments}
\author{\fontseries{el}\selectfont S\'ebastien Bourdeauducq}
\date{\fontseries{el}\selectfont july 2014}

\frame{\titlepage}

\begin{frame}
\frametitle{\fontseries{l}\selectfont Key points}
\begin{itemize}
\item High performance --- nanosecond resolution, hundreds of ns latency
\item Expressive --- describe algorithms with few lines of code
\item Portable --- treat FPGA boards as commodity
\item Modular --- separate components as much as possible
\item Flexible --- hard-code as little as possible
\end{itemize}
\end{frame}

\begin{frame}
\frametitle{\fontseries{l}\selectfont Kernels}
\begin{itemize}
\item The real-time parts of the experiments
\item Written in a subset of Python
\item Executed on a CPU embedded in a FPGA (\textit{core device})
\item Special constructs to specify timing
\end{itemize}
\end{frame}

\begin{frame}[fragile]
\frametitle{\fontseries{l}\selectfont Timing}
\begin{itemize}
\item Exact time of interactions with the outside world is kept in an internal variable
\item That variable only loosely tracks the execution time of CPU instructions
\item The value of that variable is exchanged with the \textit{RTIO core} that does precise timing
\end{itemize}
\begin{verbatimtab}
self.mains_sync.wait_edge()
for i in range(10):
    delay(10*us)
    self.X.pulse(100*MHz, 100*us)
\end{verbatimtab}
\center First X pulse is emitted exactly \SI{10}{\micro\second} after mains edge
\end{frame}

\begin{frame}[fragile]
\frametitle{\fontseries{l}\selectfont Parallel and sequential blocks}
\begin{itemize}
\item All statements in a \verb!parallel! block are executed at the same exact time
\item A \verb!parallel! block can spawn a \verb!sequential! block, where exact time increases
\item \verb!Parallel! and \verb!sequential! blocks can be arbitrarily nested
\end{itemize}
\begin{verbatimtab}
with parallel:
    with sequential:
        self.a.pulse(100*MHz, 20*us)
        self.b.pulse(200*MHz, 20*us)
    with sequential:
        self.c.pulse(300*MHz, 10*us)
        self.d.pulse(400*MHz, 20*us)
\end{verbatimtab}
\end{frame}

\begin{frame}[fragile]
\frametitle{\fontseries{l}\selectfont Object orientation and code reuse}
\begin{verbatimtab}
class Main(MPO):
    def build(self):
        self.ion1 = Ion(...)
        self.ion2 = Ion(...)
        self.transporter = Transporter(...)

    @kernel
    def run(self):
        self.ion1.cool(duration=10*us)
        self.ion2.cool(frequency=...)
        self.transporter.move(speed=...)
        self.ion1.detect(duration=...)
\end{verbatimtab}
\end{frame}

\begin{frame}[fragile]
\frametitle{\fontseries{l}\selectfont Communication with the kernel}
\begin{itemize}
\item When the kernel function calls a non-kernel function, it generates a RPC
\item The callee is executed on the host
\item The callee may receive parameters from the kernel and may return a value to the kernel
\item The kernel must have a loose real-time constraint (a long \verb!delay!) to cover communication and host delays
\item Mechanism to report results and control slow devices
\end{itemize}
\end{frame}

\begin{frame}
\frametitle{\fontseries{l}\selectfont Kernel deployment process}
\begin{enumerate}
\item Constants and called kernels are inlined
\item Loops are unrolled
\item Statements from concurrent sequential blocks are interleaved. Threads are currently unsupported.
\item Time is converted to RTIO clock units
\item The Python AST is converted to LLVM IR
\item The LLVM IR is compiled to OpenRISC machine code
\item The OpenRISC binary is sent to the core device
\item The runtime in the core device links and run the kernel
\item The kernel calls the runtime for communication (RPC) and access to core device peripherals (RTIO, DDS)
\end{enumerate}
\end{frame}

\begin{frame}[fragile]
\frametitle{\fontseries{l}\selectfont Channels and parameters}
\begin{itemize}
\item A kernel is a method of a class that derives from the \verb!MPO! class
\item The entry point for an experiment is called \verb!run! --- may or may not be a kernel
\item The \verb!MPO! class manages channels and parameters, and sets them as attributes
\item If channels/parameters are passed as constructor arguments, those are used
\item Otherwise, they are looked up in the device and parameter databases
\end{itemize}
\end{frame}

\end{document}