combox-paper

notes and other things concerning combox
git clone git://git.ricketyspace.net/combox-paper.git
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commit 1738d7d836a3d5c06512a06066e3695fc9bf71cf
parent e4a4812a1b7d2041756171f577c1ac675a9801fd
Author: Siddharth Ravikumar <sravik@bgsu.edu>
Date:   Fri, 29 Jan 2016 16:10:59 -0500

Drafted section 5.3 (Stress Testing).

Diffstat:
report/bib/combox.bib | 25+++++++++++++++++++++++++
report/chapters/5-testing.tex | 198++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
report/combox-report.pdf | 0
3 files changed, 221 insertions(+), 2 deletions(-)

diff --git a/report/bib/combox.bib b/report/bib/combox.bib @@ -73,4 +73,29 @@ number = 1, pages = {33-38}, doi = "10.1109/4236.656066", ISSN = "1089-7801", +} + +@misc{program:dump, +title = "dump script (python) for stressing testing combox", +url = "https://git.ricketyspace.net/combox-paper/plain/dumper/dump", +} + +@misc{program:dumps.el, +title = "dumps.el - Emacs Lisp magic to slurp and process output from combox", +url = "https://git.ricketyspace.net/combox-paper/plain/scripts/dumps.el", +} + +@misc{doc:benchmarks.org, +title = "benchmarks.org - document containing all information about the stress testing combox", +url = "https://git.ricketyspace.net/combox-paper/plain/notes/benchmarks.org", +} + +@misc{git:bug-eleven-fix, +title = "combox - git commit - bug eleven fix", +url = "https://git.ricketyspace.net/combox/commit/?id=5aa1ba0c1dcad62931ba27bb66bf115233086d6c", +} + +@misc{git:bug-ten-fix, +title = "combox - git commit - bug ten fix", +url = "https://git.ricketyspace.net/combox/commit?id=7ed3c9cbe6e56223b043a23408474f9df08f119e", } \ No newline at end of file diff --git a/report/chapters/5-testing.tex b/report/chapters/5-testing.tex @@ -448,27 +448,221 @@ Description of what happens in the demo follows: \section{Stress testing} +Large number of files of different sizes were dumped to the combox +directory between an one second interval to see how combox responds to +high load. The file dump size was varied from \verb+424.798190MiB+ (27 +files) to \verb+10800.000000MiB+ (180 files); the average time taken +to split a file and the total time to process all files were +calculated for each dump. + +Stress testing was first done on \verb+2015-11-08+. In mid November +the \verb+ComboxDirMonitor+ was drastically modified to make it use +the file Lock shared the instances of +\verb+NodeDirMonitor+\cite{git:bug-eleven-fix}; my hunch was that this +change in \verb+ComboxDirMonitor+ directly affected the performance of +combox and therefore the results that were got from stress testing on +\verb+2015-11-08+ would no longer be valid. Stress testing was again +done on \verb+2016-01-16+; the results of this stress test are in +sections \ref{5-st-424} to \ref{5-st-10800}, section \ref{5-st-tu} +gives information about the tools used for stress testing, section +\ref{5-st-o} contains the observations and comparisons between this +stress test and the one done on \verb+2015-11-08+, lastly section +\ref{5-st-if} reveals the issues that were found with combox by virtue +of doing the stress tests. + +\subsection{flac dump (27 files - 424.798190MiB)}\label{5-st-424} + +\begin{center} +\begin{tabular}{ll} +field & value\\ +\hline +delay between a file dump & 1s\\ +start time of processing & 11:00:54\\ +end time of processing & 11:01:38\\ +total time taken to process all files & 00:00:44\\ +no. of files & 27\\ +total size of all files & 445433187.000000 bytes (424.798190MiB)\\ +avg. file size & 16497525.000000 bytes (15.733266MiB)\\ +avg. time to split and encrypt a file & 352.583370 ms\\ +\end{tabular} +\end{center} + +\subsubsection{Differences from previous stress test (2015-11-08)} + +\begin{itemize} +\item Total time to process all files was faster by 1min3secs. +\item Average time to split and encrypt a file reduced by + 28.337963000000002ms. +\end{itemize} + +\subsection{20MiB - 90MiB dump (27 files - 1620.000000MiB)}\label{5-st-1620} + +\begin{center} +\begin{tabular}{ll} +field & value\\ +\hline +delay between a file dump & 1s\\ +start time of processing & 12:26:45\\ +end time of processing & 12:29:07\\ +total time taken to process all files & 00:02:22\\ +no. of files & 27\\ +total size of all files & 1698693120.000000 bytes (1620.000000MiB)\\ +avg. file size & 62914560.000000 bytes (60.000000MiB)\\ +avg. time to split and encrypt a file & 2670.596556ms\\ +\end{tabular} +\end{center} + +\subsubsection{Differences from previous stress test (2015-11-08)} + +\begin{itemize} +\item Total time to process all files was slower by 4secs. +\item Average time to split and encrypt a file reduced by + 25.52536999999984ms. +\end{itemize} + +\subsection{20MiB - 90MiB dump (99 files - 5940.000000MiB)}\label{5-st-5940} + +\begin{center} +\begin{tabular}{ll} +field & value\\ +\hline +delay between a file dump & 1s\\ +start time of processing & 13:10:16\\ +end time of processing & 13:19:26\\ +total time taken to process all files & 00:09:10\\ +no. of files & 99\\ +total size of all files & 6228541440.000000 bytes (5940.000000MiB)\\ +avg. file size & 62914560.000000 bytes (60.000000MiB)\\ +avg. time to split and encrypt a file & 2979.647586ms\\ +\end{tabular} +\end{center} + +\subsubsection{Differences from previous stress test (2015-11-08)} + +\begin{itemize} +\item Total time to process all files was faster by 59secs. +\item Average time to split and encrypt a file increased by + 206.20906100000002ms. +\end{itemize} + +\subsection{20MiB - 90MiB dump (180 files - 10800.000000MiB)}\label{5-st-10800} + +\begin{center} +\begin{tabular}{ll} +field & value\\ +\hline +delay between a file dump & 1s\\ +start time of processing & 13:42:06\\ +end time of processing & 14:00:10\\ +total time taken to process all files & 00:18:04\\ +no. of files & 180\\ +total size of all files & 11324620800.000000 bytes (10800.000000MiB)\\ +avg. file size & 62914560.000000 bytes (60.000000MiB)\\ +avg. time to split and encrypt a file & 3423.087539ms\\ +\end{tabular} +\end{center} + +\subsubsection{Differences from previous stress test (2015-11-08)} + +\begin{itemize} +\item Total time to process all files was slower by 1min2secs +\item Average time to split and encrypt a file increased by + 399.87623299999996ms. +\end{itemize} + +\subsection{Tools used}\label{5-st-tu} + +The \verb+dump+ script\cite{program:dump} was used to dump files to +the combox directory between one second intervals; a night of Emacs +Lisp indulgence made it possible to quickly slurp the required data +from the combox output and calculate the average time to split and +encrypt a file and the total amount of time taken to process the files +for a given dump\cite{program:dumps.el}; lastly \verb+org-mode+ was +used to document all data gathered during stress +testing\cite{doc:benchmarks.org}. + +\subsection{Observations}\label{5-st-o} \begin{figure}[h] \centering \input{graphs/tot-time.tex} \caption{time to process all files} +\label{fig:5-st-tt} \end{figure} \begin{figure}[h] \centering \input{graphs/avg-time-sae.tex} \caption{avg. time to split and encrypt} +\label{fig:5-st-atsae} \end{figure} + +\begin{itemize} +\item Figure \ref{fig:5-st-tt} shows the time it takes combox to + process files for a given file dump\footnote{A ``file dump'' here + means a bunch of files copied to the combox directory between 1 + sec intervals.}. As can be observed from the graph, the total time + taken to process all the files tends almost linearly increase with + the increase in the size of the file dump\footnote{The ``size of the + file dump'' is the total size of all files in a given file dump.}. +\item Figure \ref{fig:5-st-atsae} show the average time it takes + combox to split and encrypt a file for a given file dump. There is a + steep increase in the average time from the \verb+424.798190MiB+ + dump and the \verb+1620.000000MiB+ dump, after which the average + time to split and encrypt a file seems to almost linearly increase; + The main reason for this is that the average file size for dumps + from \verb+1620.000000MiB+ to \verb+10800.000000MiB+ are the same. +\end{itemize} + \begin{figure}[h] \centering \input{graphs/tot-time-diff.tex} \caption{time to process all files - difference between 2015 and 2016} +\label{fig:5-st-tt-diff} \end{figure} \begin{figure}[h] \centering \input{graphs/avg-time-sae-diff.tex} \caption{avg. time to split and encrypt - difference between 2015 and 2016} -\end{figure}- \ No newline at end of file +\label{fig:5-st-atsae-diff} +\end{figure} + +\begin{itemize} +\item Figure \ref{fig:5-st-tt-diff} shows the graphs for the total + amount of time taken to process all files for a given file dump in + the \verb+2016-01-16+ and \verb+2015-11-8+ stress test. The amount + of time needed to process all fills seems to be reduced for the + \verb+5940.000000MiB+ file dump when compared to the \verb+2015+ + stress test results and it seems to be slightly higher for the + \verb+10800.000000MiB+ file dump when compared to the \verb+2015+ + stress test. +\item Similarly, figure \ref{fig:5-st-atsae-diff} shows the graphs for + the average time to split and encrypt for a given file dump in the + \verb+2016-01-16+ and the \verb+2015-11-8+ stress test. The average + time taken seems to able almost the same for the + \verb+424.798190MiB+ and the \verb+1620.000000+ dump, but for the + \verb+5940.000000MiB+ and the \verb+10800.000000MiB+ dump the + average time taken seems to higher for the \verb+2016+ stress test + when compared to the \verb+2015+ stress test. +\end{itemize} + +\subsection{Issues found}\label{5-st-if} + +\begin{itemize} +\item Initially when combox was stress tested with huge files, combox + would get overwhelmed leading to the computer running out of memory + and the load average sometimes peaking at \verb+8+. At first, it was + assumed that there was a bug in combox which caused this to happen, + but later it was found that \verb+watchdog+\cite{pylib:watchdog} was + generating a large number ``file modified'' events when a huge file + (\verb+~500MiB+ was modified). To prevent \verb+watchdog+ from + generating a large number ``file modified'' events for a single + modification of a huge file, a delay proportional to the size of the + file was created in the \verb+on_modified+ callback methods in both + \verb+ComboxDirMonitor+ and + \verb+NodeDirMonitor+\cite{git:bug-ten-fix}, this fixed the + issue. Also, this it might be useful to note here that this was + ``the'' hardest issue I dealt with in working on combox. +\end{itemize}+ \ No newline at end of file diff --git a/report/combox-report.pdf b/report/combox-report.pdf Binary files differ.