Changeset c28ea4e for doc/theses/thierry_delisle_PhD/thesis/text/io.tex

Timestamp:

Nov 4, 2020, 2:56:30 PM (3 years ago)

Author:

Colby Alexander Parsons <caparsons@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, master, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

eeb5023

Parents:

4b30e8cc (diff), a3f5208a (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Merge branch 'master' of plg.uwaterloo.ca:software/cfa/cfa-cc

File:

• doc/theses/thierry_delisle_PhD/thesis/text/io.tex (modified) (2 diffs)

doc/theses/thierry_delisle_PhD/thesis/text/io.tex

@@ -1 @@
-\chapter{I/O}
+\chapter{User Level \glsxtrshort{io}}
+As mentionned in Section~\ref{prev:io}, User-Level \glsxtrshort{io} requires multiplexing the \glsxtrshort{io} operations of many \glspl{thrd} onto fewer \glspl{proc} using asynchronous \glsxtrshort{io} operations. Various operating systems offer various forms of asynchronous operations and as mentioned in Chapter~\ref{intro}, this work is exclusively focuesd on Linux.
 
 \section{Existing options}
+Since \glsxtrshort{io} operations are generally handled by the
 
 \subsection{\texttt{epoll}, \texttt{poll} and \texttt{select}}
@@ -7 +9 @@
 \subsection{Linux's AIO}
 
+
+
+\begin{displayquote}
+        AIO is a horrible ad-hoc design, with the main excuse being "other,
+        less gifted people, made that design, and we are implementing it for
+        compatibility because database people - who seldom have any shred of
+        taste - actually use it".
+
+        But AIO was always really really ugly.
+
+        \begin{flushright}
+                -- Linus Torvalds\cit{https://lwn.net/Articles/671657/}
+        \end{flushright}
+\end{displayquote}
+
+Interestingly, in this e-mail answer, Linus goes on to describe
+``a true \textit{asynchronous system call} interface''
+that does
+``[an] arbitrary system call X with arguments A, B, C, D asynchronously using a kernel thread''
+in
+``some kind of arbitrary \textit{queue up asynchronous system call} model''.
+This description is actually quite close to the interface of the interface described in the next section.
+
 \subsection{\texttt{io\_uring}}
+A very recent addition to Linux, \texttt{io\_uring}\cit{io\_uring} is a framework that aims to solve many of the problems listed with the above mentioned solutions.
 
-\subsection{Extra Kernel Threads}
+\subsection{Extra Kernel Threads}\label{io:morethreads}
+Finally, if the operating system does not offer any satisfying forms of asynchronous \glsxtrshort{io} operations, a solution is to fake it by creating a pool of \glspl{kthrd} and delegating operations to them in order to avoid blocking \glspl{proc}.
 
 \subsection{Discussion}