<html>
<head>
<style><!--
.hmmessage P
{
margin:0px;
padding:0px
}
body.hmmessage
{
font-size: 12pt;
font-family:Calibri
}
--></style></head>
<body class='hmmessage'><div dir='ltr'>Hi all,<div><br></div><div>Following our previous posts (<a href="http://lists.ros.org/lurker/message/20140918.011916.e0e9cd9e.en.html" target="_blank">http://lists.ros.org/lurker/message/20140918.011916.e0e9cd9e.en.html</a> and <a href="http://lists.ros.org/lurker/message/20140929.022230.7c75e176.en.html" target="_blank">http://lists.ros.org/lurker/message/20140929.022230.7c75e176.en.html</a>) , again we are posting some updates here in a separate thread.</div><div><br></div><div>We did some tests to demonstrate the effectiveness of the PREEMPT_RT patched Linux kernel, compared with the vanilla kernel coming with Ubuntu. To be more specific, jitters in ROS message communications (both topic- and service-based) upon the non-real-time and real-time kernels are recorded, while the source code of the test tries to maintain a fixed communication rate (10kHz in our case). The source code can be downloaded from:</div><div><a href="http://micros.nudt.edu.cn/ros/attachments/download/6440/ros_rt_test_src.tar.gz" target="_blank">http://micros.nudt.edu.cn/ros/attachments/download/6440/ros_rt_test_src.tar.gz</a></div><div><br></div><div>And the results are shown in the charts below:</div><div><a href="http://micros.nudt.edu.cn/ros/attachments/download/6435/topic_one_subscriber.png" target="_blank">http://micros.nudt.edu.cn/ros/attachments/download/6435/topic_one_subscriber.png</a></div><div><a href="http://micros.nudt.edu.cn/ros/attachments/download/6436/topic_two_subscriber.png" target="_blank">http://micros.nudt.edu.cn/ros/attachments/download/6436/topic_two_subscriber.png</a></div><div><a href="http://micros.nudt.edu.cn/ros/attachments/download/6437/topic_four_subscriber.png" target="_blank">http://micros.nudt.edu.cn/ros/attachments/download/6437/topic_four_subscriber.png</a></div><div><a href="http://micros.nudt.edu.cn/ros/attachments/download/6438/topic_eight_subscriber.png" target="_blank">http://micros.nudt.edu.cn/ros/attachments/download/6438/topic_eight_subscriber.png</a></div><div><a href="http://micros.nudt.edu.cn/ros/attachments/download/6439/service.png" target="_blank">http://micros.nudt.edu.cn/ros/attachments/download/6439/service.png</a></div><div><br></div><div>The test environment is described below:</div><div>OS: Ubuntu 12.04 32-bit</div><div>Vanilla kernel version: 3.8.0</div><div>Real-time kernel version: linux-3.8.13-rt16</div><div>ROS version: Groovy</div><div><div><br>Best regards,<div>Yanzhen</div><div><br></div></div></div> </div></body>
</html>