doc/slides/qsnet/slides.tex

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\fancyhead[C]{\Large\textbf{QsNet Support}}
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\begin{document}

\slidepagestyle{fancy}

% The presentation begins here.

\begin{slide}
  %\slideheading{The Big Picture}
\begin{center}
\epsfig{file=slurm.eps,scale=0.50}
\end{center}
\end{slide}

\begin{slide}
  \slideheading{Goals}
  \small
  \begin{itemize}
  \item Encapsulate QsNet details so QSW include files, data structures, etc.
        do not "pollute" the rest of slurm.
  \item Provide the simplest API possible for manipulating QsNet interconnect
        resources, but no simpler.
  \item Checkpointability of internal library state for transfer to failover
        slurmctld.
  \item Interfaces to pack/unpack data structures in network byte order for
        use in slurmd packet protocol discussed last week.
  \item API calls compatable with standalone programs like pdsh and
        long-running servers like slurmctld.
  \item Both client (pdsh/slurmctld) and server (qshd/slurmd) side functions
        provided.
  \end{itemize}
\end{slide}

\begin{slide}
  \slideheading{Library Initialization}
  \small
  Initialize/finalize the library, optionally saving/restoring internal state.
  \begin{verbatim}
  int qsw_init(qsw_libstate_t restorestate);
  void qsw_fini(qsw_libstate_t savestate);
  \end{verbatim}
  Allocate/free a {\tt qsw\_libstate\_t} to represent internal state.
  \begin{verbatim}
  int qsw_alloc_libstate(qsw_libstate_t *lsp);
  void qsw_free_libstate(qsw_libstate_t ls);
  \end{verbatim}
  Pack/unpack a {\tt qsw\_libstate\_t} into a format suitable for transmitting
  over the network, writing to checkpoint file, etc..
  \begin{verbatim}
  int qsw_pack_libstate(qsw_libstate_t ls, void *buf, int size);
  int qsw_unpack_libstate(qsw_libstate_t ls, void *buf, int size);
  \end{verbatim}
\end{slide}

\begin{slide}
  \slideheading{Client Side Functions}
  \small
  Create all the interconnect information necessary to start a parallel 
  program including Elan capability, program description number, etc..
  \begin{verbatim}
  int qsw_setup_jobinfo(qsw_jobinfo_t job, int nprocs, 
                        bitstr_t *nodeset, int cyclic_alloc);
  \end{verbatim}
  Allocate/free a {\tt qsw\_jobinfo\_t} to represent job information.
  \begin{verbatim}
  int qsw_alloc_jobinfo(qsw_jobinfo_t *jobp);
  void qsw_free_jobinfo(qsw_jobinfo_t job);
  \end{verbatim}
  Pack/unpack a {\tt qsw\_jobinfo\_t} into a format suitable for transmitting
  over the network.
  \begin{verbatim}
  int qsw_pack_jobinfo(qsw_jobinfo_t job, void *buf, int size);
  int qsw_unpack_jobinfo(qsw_jobinfo_t job, void *buf, int size);
  \end{verbatim}
\end{slide}


\begin{slide}
  \slideheading{Server Side Functions}
  \small
  1: Fork.  Wait.  Destroy program group with {\tt qsw\_prog\_reap}.
  \begin{verbatim}
  int qsw_prog_reap(qsw_jobinfo_t jobinfo);
  \end{verbatim}
  2: Initialize program description and capability with {\tt qsw\_prog\_init}.
  Fork N times.  Wait N times.  Exit. Destroy capability with {\tt qsw\_prog\_fini}.
  \begin{verbatim}
  int qsw_prog_init(qsw_jobinfo_t jobinfo, uid_t uid);
  int qsw_prog_fini(qsw_jobinfo_t jobinfo);
  \end{verbatim}
  3: (N instances) Attach to a hardware context with {\tt qsw\_attach}.  
  Set up environment.  Fork.  Wait.  Exit.
  \begin{verbatim}
  int qsw_attach(qsw_jobinfo_t jobinfo, int procnum);
  \end{verbatim}
  4: Setuid to the user.  Exec.
\end{slide}

\begin{slide}
  \slideheading{Discussion Points}
  \small
  \begin{itemize}
  \item If library is initialized, {\tt qsw\_setup\_jobinfo} allocates
  program descriptions and Elan hardware contexts sequentially, else random.
  \item Library internal state checkpoint capability available for failover.
  \item Pack/Unpack routines translate between host/network byte order.
  Macros used to permit assertions about size of incoming data types before
  type promotion.
  \item bitstr\_t used to represent ``nodeset''.  Bit positions are elan 
  addresses.  There is no provision for converting between Elan address and
  hostname.
  \item Elan include files are not required outside of qsw.c.
  \item configure --with-elan or qsw.c becomes an empty source file.
  \end{itemize}
\end{slide}

\begin{slide}
  \slideheading{pack.c}
  \tiny
  htonl/ntohl, htons/ntohs functions with macro wrappers with many assertions:
  \begin{verbatim}
  void pack32(uint32_t val, void **bufp, int *lenp);
  void pack16(uint16_t val, void **bufp, int *lenp);
  void unpack32(uint32_t *val, void **bufp, int *lenp);
  void unpack16(uint16_t *val, void **bufp, int *lenp);
  \end{verbatim}
  Example - qsw\_pack\_libstate(qsw\_libstate\_t ls, void *data, int len)
  \begin{verbatim}
  pack32(ls->ls_magic, &data, &len);
  pack32(ls->ls_prognum, &data, &len);
  pack32(ls->ls_hwcontext, &data, &len);
  \end{verbatim}
  Example - qsw\_unpack\_libstate(qsw\_libstate\_t ls, void *data, int len)
  \begin{verbatim}
  unpack32(&ls->ls_magic, &data, &len);
  unpack32(&ls->ls_prognum, &data, &len);
  unpack32(&ls->ls_hwcontext, &data, &len);
  \end{verbatim}
\end{slide}
 

\end{document}