[or-cvs] r15936: Some small corrections. (projects/hidserv/trunk/doc)

[kloesing at seul.org]

Author: kloesing
Date: 2008-07-15 07:24:30 -0400 (Tue, 15 Jul 2008)
New Revision: 15936

Modified:
   projects/hidserv/trunk/doc/discussion.tex
Log:
Some small corrections.

Modified: projects/hidserv/trunk/doc/discussion.tex
===================================================================
--- projects/hidserv/trunk/doc/discussion.tex	2008-07-15 10:43:41 UTC (rev 15935)
+++ projects/hidserv/trunk/doc/discussion.tex	2008-07-15 11:24:30 UTC (rev 15936)
@@ -13,7 +13,7 @@
 \maketitle
 
 \begin{abstract}
-This document describes possible design changes aiming at improving
+This document describes possible design changes aiming at improving the
 performance of Tor Hidden Services. The ideas for these improvements come
 from an earlier analysis of possible performance
 bottlenecks\footnote{\url{http://freehaven.net/~karsten/hidserv/perfanalysis-2008-06-15.pdf}}.
@@ -129,7 +129,7 @@
 they can be kept in a pool for later internal circuit usage. However, in
 addition to being slow anyway, these circuits might need to be extended for
 another usage which will make them even slower. Therefore, they should be
-discarded after they reach a certain length, e.g.\ 6 hops.
+discarded after they exceed a certain length, e.g.\ 6 hops.
 %
 \item[Anonymity Issues with Loser Circuits] Other than stated in the analysis, there should not be any
 anonymity issues with slower circuits, because they were never told to be used as introduction circuits.
@@ -155,10 +155,10 @@
 
 \begin{description}
 \item[Performance Improvement of 2 Seconds]
-Figure~\ref{fig:introestmean} shows the simulated mean introduction circuit
+Figure~\ref{fig:introestmean} shows simulated mean introduction circuit
 cannibalization and extension times for timeouts between 10 and 60 seconds.
 For a timeout of 30 seconds the performance gain would be approximately 2
-seconds.
+seconds as opposed to the current timeout of 60 seconds.
 %
 \begin{figure}[tb]
 \centering
@@ -176,7 +176,7 @@
 %
 \item[Increased Network Load] There will be an increased share of circuits
 that are discarded after the new timeout expires, but would have been
-completed within the existing timeout of 60 seconds. Figure~\ref{fig:introestattempts} visualizes the increased number of circuit cannibalization and extension attempts for lower timeouts.
+completed within the existing timeout of 60 seconds. Figure~\ref{fig:introestattempts} visualizes the simulated increased number of circuit cannibalization and extension attempts for lower timeouts.
 %
 \begin{figure}[tb]
 \centering
@@ -200,7 +200,7 @@
 connections to more than one hidden service at a time.}
 
 \begin{description}
-\item[Performance Improvement of 4.5 Seconds] It is assumed that a
+\item[Performance Improvement of 4.7 Seconds] It is assumed that a
 popular hidden service cannot make use of cannibalization for
 connecting to rendezvous points, but needs to create new circuits.
 Therefore, the circuit creation time needs to be added to the current
@@ -214,7 +214,7 @@
 0.139 & 1.203 & 2.504 & 4.659 & 5.234 & 56.090
 \end{tabular}
 %
-\item[Dependency on Regular Hidden Service Protocol] This design change only
+\item[Dependency on Regular Protocol] This design change only
 makes sense if the design change described in Section~\ref{sec:rendsimpl}
 is \emph{not} applied.
 \item[Higher Number of Internal Circuits] A hidden service would have to
@@ -230,23 +230,23 @@
 still be used for other purposes afterwards.}
 
 \begin{description}
-\item[Performance Improvement of 3.5 Seconds] The effect of choosing
+\item[Performance Improvement of 3.7 Seconds] The effect of choosing
 the fastest 3 out of 5 (4, 6) circuit creations as introduction points has been
 evaluated using previously measured data, too. Therefore, circuit
 establishment times were derived from log files and written to an array.
 Afterwards, a simulation with 10,000 runs was performed picking 5 (4, 6) random values
 and using
 the 3 lowest values in contrast to picking only 3 values at random. The
-result is that the mean time of the 3-out-of-3 approach is 8 seconds, while the
-mean time of the 3-out-of-5 approach is 4.5 seconds. The results are given in the table below.
+result is that the mean time of the 3-out-of-3 approach is 8.1 seconds, while the
+mean time of the 3-out-of-5 approach is 4.4 seconds. The results are given in the table below.
 
 % R: three <- read.csv("3outof3.csv",sep = ",",header=FALSE, row.names=NULL); four <- read.csv("3outof4.csv",sep = ",",header=FALSE, row.names=NULL); five <- read.csv("3outof5.csv",sep = ",",header=FALSE, row.names=NULL); six <- read.csv("3outof6.csv",sep = ",",header=FALSE, row.names=NULL); summary(three); summary(four); summary(five); summary(six)
 \begin{tabular}{crrrrrr}
 Intro. Pnts. & Min. & 1st Qu. & Median & Mean & 3rd Qu. & Max.\\\hline
-3 & 1.023 & 5.020 & 6.820 & 8.060 & 9.720 & 40.500\\
-4 & 0.882 & 3.810 & 5.000 & 5.420 & 6.470 & 30.900\\
-5 & 0.786 & 3.210 & 4.190 & 4.430 & 5.370 & 19.200\\
-6 & 0.578 & 2.830 & 3.700 & 3.870 & 4.710 & 12.100\\
+3 & 1.023 & 5.017 & 6.820 & 8.060 & 9.718 & 40.490\\
+4 & 0.882 & 3.811 & 4.997 & 5.421 & 6.472 & 30.950\\
+5 & 0.786 & 3.211 & 4.188 & 4.430 & 5.367 & 19.230\\
+6 & 0.578 & 2.826 & 3.702 & 3.865 & 4.705 & 12.080\\
 \end{tabular}
 %
 \item[Network Load] The effect on network load is minimal, because the hidden service can reuse the slower internal circuits for other purposes.
@@ -285,7 +285,7 @@
 \begin{figure}[tb]
 \centering
 \includegraphics[width=0.8\textwidth]{firstpub.png}
-\caption{Time until first descriptor upload as a function of stabilization time}
+\caption{Time until first descriptor upload as a function of stabilization time (arrow denotes current stabilization time of 30 seconds)}
 \label{fig:firstpub}
 \end{figure}
 
@@ -293,7 +293,8 @@
 \begin{figure}[tb]
 \centering
 \includegraphics[width=0.8\textwidth]{descup.png}
-\caption{Number of uploaded descriptors as a function of stabilization time}
+\caption{Number of uploaded descriptors as a function of stabilization time
+(arrow denotes current stabilization time of 30 seconds)}
 \label{fig:stabtime}
 \end{figure}
 
@@ -311,7 +312,7 @@
 discussion of the possible consequences.
 
 \begin{description}
-\item[Higher Reliability] An evaluation has shown that 14.7\% of all
+\item[Higher Reliability] An evaluation of log statements has shown that 14.7\% of all
 descriptor uploads to the three central hidden service authorities failed.
 A subsequent analysis has confirmed these results for the distributed
 storage for hidden service descriptors with a failure rate of 13.7\%.