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embedded_systems:ethercat:test_and_tune_rt [2018-12-14 13:59] – mgehrig2embedded_systems:ethercat:test_and_tune_rt [2023-04-11 11:12] (aktuell) – Urs Graf
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 ''max. jitter OS = min jitter EtherCAT bus'' ''max. jitter OS = min jitter EtherCAT bus''
  
-See [[embedded_systems:ethercat:distributed_clocks|Distributed Clocks]] for more information.+If the master cannot guarantee a stable clock, the masterShift mode is recommended. 
 + 
 +See [[embedded_systems:ethercat:understanding_ethercat:understanding_sync_with_dc|Distributed Clocks]] for more information.
  
  
Zeile 26: Zeile 28:
 ==== Cyclictest ==== ==== Cyclictest ====
 The Cyclictest is a software that can be used to easily measure the maximum jitter of a system. The Cyclictest is a software that can be used to easily measure the maximum jitter of a system.
-[[software:linux:cyclictest:start|This page]] explains how to install and use the software.+[[software:linux:realtime:cyclictest|Cyclictest]] explains how to install and use the software.
 === Quick Measurement === === Quick Measurement ===
 ''sudo ./cyclictest -p 80 -t5 -n'' ''sudo ./cyclictest -p 80 -t5 -n''
 +
  
 ===== Improve RT performance =====  ===== Improve RT performance ===== 
 If the RT performance is not sufficient, the maximum jitter could be reduced with the following measures: If the RT performance is not sufficient, the maximum jitter could be reduced with the following measures:
 +
 +==== Intel Scaling Governor ====
 +Modern processors change the CPU frequency depending on the load to save power.
 +With an RT-OS this can lead to increased jitter.
 +If the frequency is fixed, the RT performance can be improved.
 +ATTENTION: If the CPU is fixed at a high temperature, the CPU can run hot. If the Governor is changed manually, the CPU temperature should be monitored!
 +
 +The frequency is controlled by the OS by a [[https://wiki.archlinux.org/index.php/CPU_frequency_scaling#Scaling_governors|scaling governor]].
 +The ''performance'' governor should run the cpu at the maximum frequency.
 +
 +To get the current active governor:\\
 +''cpupower frequency-info''
 +
 +To set the governor:\\
 +''sudo cpupower frequency-set -g powersave''
 + 
 +
 +==== Intel cstates ====
 +Intel cstates indicate the power saving state of the processor.
 +These states can be locked with kernel parameters on the C0 state (no power saving measures).
 +
 +{{:embedded_systems:ethercat:controlling_processor_c-state_usage_in_linux_v1.1_nov2013.pdf|Background information}}
 +
 +Display current kernel parameters:\\
 +''cat /proc/cmdline''
 +
 +Add the following [[software:linux:linux_os:kernel_parameter|kernel parameters]]:
 +
 +  * cpuidle.off=1
 +  * intel_idle.max_cstate=0
 +
  
  

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embedded_systems/ethercat/test_and_tune_rt.1544792385.txt.gz · Zuletzt geändert: 2018-12-14 13:59 von mgehrig2