Recent posts to Reducing Jitterhttps://forge.codesys.com/forge/talk/Runtime/thread/5cc16d686b/2020-02-27T16:26:24.217000ZRecent posts to Reducing JitterReducing Jitter2020-02-27T16:26:24.217000Z2020-02-27T16:26:24.217000Zarj3090https://forge.codesys.com/u/arj3090/https://forge.codesys.com73bc4881490abceb593b6b84d10cbb2610bb4c5f<div class="markdown_content"><blockquote>
<p><strong>Edwin Schwellinger hat geschrieben:</strong><br/>
Hi,<br/>
which jitter do you see , before you start changing anything?</p>
</blockquote>
<p>These are the values before and after changes:<br/>
Before -> After<br/>
129 -> 95<br/>
157 -> 117<br/>
154 -> 66<br/>
102 -> 62<br/>
521 -> 147</p>
<p>This was only a short term test over a few hours so it may not be very accurate.</p></div>Reducing Jitter2020-02-27T16:26:23.336000Z2020-02-27T16:26:23.336000Zeschwellingerhttps://forge.codesys.com/u/eschwellinger/https://forge.codesys.comcb71e017a40e4c732c68b69757d770d7cec4b9db<div class="markdown_content"><p>Hi,<br/>
which jitter do you see , before you start changing anything?</p>
<p>BR<br/>
Edwin</p></div>Reducing Jitter2020-02-27T16:26:20.874000Z2020-02-27T16:26:20.874000Zarj3090https://forge.codesys.com/u/arj3090/https://forge.codesys.come5cf93b21b947879ca933406965c9d88116caf0f<div class="markdown_content"><p>I have been experimenting with reducing jitter on a Raspberry Pi with the Preempt RT patch. The one thing I found that seemed to help was to set the CodeSys process to a nice level of -20. My test is not very scientific, but enough to see results. I have a program with 5 tasks and they are all set to free floating processor core use. My before and after jitter results:</p>
<p>Before -> After<br/>
129 -> 95<br/>
157 -> 117<br/>
154 -> 66<br/>
102 -> 62<br/>
521 -> 147</p>
<p>So my question is whether changing the nice value could have other side effects?</p>
<p>This is the method I used to change the CodeSys nice value:</p>
<p>Connect using SSH<br/>
cd /etc/init.d<br/>
sudo nano codesyscontrol</p>
<p>insert the "--nicelevel -20" into the following line :</p>
<p>start-stop-daemon --start --background --make-pidfile --pidfile $PIDFILE --nicelevel -20 --chd$</p>
<p>reboot</p></div>