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<link rel="shortcut icon" href=images/pluto-symbol.jpg type="image/x-icon" />
The Pluton Framework: Performance
<a href=index.html>
<img height=100 src=images/pluto-charon.jpg ALT="[Pluto Charon Image]">
<h2 align=center>The Pluton Framework: Performance</h2>
Each service exchange involves the following actions:
<table border=1>
<tr><td>1<td> Connect to A Unix Socket<td align=center> --&gt; <td> </tr>
<tr><td>2<td> <td align=center> --&gt; <td>Accept of a connection </tr>
<tr><td>3<td>Write of Request Data <td align=center> --&gt; <td> </tr>
<tr><td>4<td> <td align=center> --&gt; <td>Read of Request Data </tr>
<tr><td>5<td> <td align=center>&lt;-- <td>Write of Response Data </tr>
<tr><td>6<td>Read of Response Data <td align=center>&lt;-- <td> </tr>
<tr><td>7<td>close() <td align=center>&lt;--&gt; <td>close() </tr>
<p>Including context switches, this set of actions clearly come at a
cost. The dominant cost is the CPU overhead in performing the actions
and the consequential latency.
<h4>CPU overhead</h4>
It varies depending on the OS (pluton runs on FreeBSD, Linux and OS/X)
but on a relatively ancient CPU (circa 2003) the CPU cost of a zero
length exchange is approximately 300 microseconds or .3 of a
millisecond and on a modern CPU (circa 2006) the cost is around .1 of
a millisecond.
<p>Increasing the size of the request changes the dynamics such that
the transfer cost eventually dominates all other costs. The following
table shows the CPU cost and latency of different sized requests
spread across a menagerie of CPUs.
<table border=1>
<tr><th colspan=5>CPU Cost per request (milliseconds)</tr>
<tr><th>Request Size (bytes)
<th>PPC 1.5Ghz<br>OS/X 10.4
<th>P-III 886MHz<br>FBSD4
<th>dual P-4 3Ghz<BR>RHEL4
<th>Athlon 64 X2 Dual Core 3800+<BR>FBD6.2
<tr><td align=right>0<td align=right>0.31<td>0.22<td>0.11<td>0.09 </tr>
<tr><td align=right>1,000<td align=right>0.33<td>0.23<td>0.11<td>0.10 </tr>
<tr><td align=right>2,000<td align=right>0.34<td>0.24<td>0.11<td>0.10 </tr>
<tr><td align=right>8,000<td align=right>0.36<td>0.29<td>0.13<td>0.12 </tr>
<tr><td align=right>16K<td align=right>0.50<td>0.37<td>0.14<td>0.14 </tr>
<tr><td align=right>32K<td align=right>0.69<td>0.66<td>0.15<td>0.19 </tr>
<tr><td align=right>64K<td align=right>1.05<td>1.57<td>0.18<td>0.31 </tr>
<tr><td align=right>128K<td align=right>1.98<td>3.13<td>0.30<td>0.59 </tr>
<tr><td align=right>256K<td align=right>3.52<td>5.87<td>0.60<td>1.38 </tr>
<tr><td align=right>1M<td align=right>11.90<td>20.93<td>2.59<td>5.11 </tr>
<tr><td align=right>2M<td align=right>21.40<td>41.15<td>4.83<td>10.03 </tr>
<tr><td align=right>4M<td align=right>41.33<td>79.10<td>9.43<td>19.80 </tr>
Here is a graph of the response times at the lower end of the exchange
<img src=images/responseTimes2.jpg>
and here is a graph of all data points:
<img src=images/responseTimes.jpg>
<font size=-1>
$Id: performance.html 260483 2009-10-16 18:47:56Z markd $
&copy; Copyright Yahoo! Inc, 2007
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