\documentclass{article}
\input{6824-preamble}

\begin{document}
\psetnum{11}
\date{2004/04/07}

\begin{pset}
  The confirmation operation is necessary to ensure that a page has
  successfully been transferred to a processor before requests for
  that page are sent to it. Suppose the confirmation message were not
  used. Then we could imagine a scenario where processor $P_1$
  initially has ownership of a page, and processor $P_2$ requests it.
  Then the manager will ask $P_1$ to send $P_2$ the page. The
  confirmation process would ensure that the \texttt{info[p].lock}
  lock is held until the transfer is complete. If it were not used,
  then a request for the same page from some processor $P_3$ might
  come in while the page was being transferred, and the manager would
  send it to $P_2$, which would not know what to do with it because it
  has not yet received the page. Chaos ensues.
\end{pset}

\end{document}
