Conflict between RTI execution time and Message Queue

PowerPmac1.zip

Attached is a project wich use Message Queue(see read_me.txt).

I want to transfert data between rticplc and bgcplc. To do that, I use Message Queue.

Everything works fine until I open SSH or SFTP connection with PPMAC. Each time I open SSH connection and running "gpascii -2" or each time I open a window in PPMAC IDE (like "STATUS"), execution time of rticplc and bgcplc increase up to 30ms when it was executed in 350µs.

Did someone already observed this phenomenom and/or has already corrected it ?

 

 

Attached is a project wich use Message Queue(see read_me.txt).

 

I want to transfert data between rticplc and bgcplc. To do that, I use Message Queue.

Everything works fine until I open SSH or SFTP connection with PPMAC. Each time I open SSH connection and running "gpascii -2" or each time I open a window in PPMAC IDE (like "STATUS"), execution time of rticplc and bgcplc increase up to 30ms when it was executed in 350µs.

 

Did someone already observed this phenomenom and/or has already corrected it ?

The powerpmac uses Xenomai. When you make standard linux system calls the thread you are making your call from switches from what is called primary mode to secondary mode and therefore is subject to sharing its time with regular linux processes such as ssh gpascii etc. Primary modes are scheduled by the Xenomai kernel, and benefits from hard real-time scheduling latencies, in secondary mode it is an ordinary Linux thread.

http://www.xenomai.org/index.php/Porting_POSIX_applications_to_Xenomai

http://www.xenomai.org/documentation/trunk/html/api/group__posix__mq.html

Thank you for your answer.

I will try to change my program to "disable" the latency due to the message queu.