Plz help me finding the logic for implementing the BCC2 and ECC2 in OSEK RTOS

Hi,

I think for BCC2 you have to make no big changes. BCC2 is the same like BCC1 plus the support of more than one task with the same priority and multiple task activation. ECC2 is like ECC1 plus more than one task with the same priority and multiple activation of basic tasks. Basic tasks and extended tasks differ in their number of states. Basic tasks in OSEK-OS can be in the states 'ready', 'running', and suspended. Extended tasks can be additionally in the state 'waiting'. For your scheduling policy this means, that you have to support non-preemptive scheduling for basic tasks and preemptive scheduling for extended tasks. In BCC2 and ECC2 tasks with the same priority are allowed. In the case of two or more readdy tasks this means that the scheduler always chooses the task with the lower activation time and switches it to the 'running' state.

Yes, I have source code of an OSEK-OS, but sorry, I am not allowed to give it to you.

Best regards,

Olaf Barheine

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hi Barheine,

thanks for ur reply..

"In BCC2 and ECC2 tasks with the same priority are allowed. In the case of two or more readdy tasks this means that the scheduler always chooses the task with the lower activation time and switches it to the 'running' state."

sorry i didnt get u.... please give me an example so that i can get an idea... in my rtos i dont have activation time concept... i didnt get clear with activation time concept... please tell some thing about activation time.... so that i will imple ment in my rtos code...

with regards, Alagusakthi

Hello,

In OSEK extended tasks can be running, waiting, suspended or in the ready state. The activation time is the time a task changes from suspended into the ready state. At that point the tasks gets the processor and starts its first command. This is nothing special. Earlier you have written that you have already implemeted BCC1 and ECC1. So, you should already have an ActivateTask()-function.

Maybe, it would be easier for you to study the specification of OSEK, especially the state modell, the scheduling policy, the task activation etc. There is also a book about OSEK from Matthias Homann who gives an good overview and introduction, but it is German. Did you already visit the homepage

?

Best regards,

Olaf Barheine

hi Barheine,

thanks for ur mail.... yah now i understood the activate time ..... yes in my RTOS i have ActivateTask function... that will change task frm suspend to ready state or even to running state... its all happening in my rtos with out any problem....

will u please tell me how the lower activation time helps me to implement BCC2 and ECC2...

yes i visited that site already... but i didnt study the OSEK from Matthias Homann book for RTOS... i will serach that wesite now...

with regards, Alagusakthi

Hello,

I think this is very straightforward:

1) The scheduler searches all tasks which are in the 'ready' or 'running' state 2) From this set of running and ready tasks the scheduler determines the set of tasks with the highest priority. 3) From this set of highest priorty tasks the scheduler chooses that one, which is the oldest, i.e. that one with the lowest activation time.

That's all, isn't it? But remember that for BCC2 the tasks are non-preemptive and for ECC2 preemptions are allowed.

Best reagrds,

Olaf Barheine

Hello,

I think this is very straightforward:

1) The scheduler searches all tasks which are in the 'ready' or 'running' state 2) From this set of running and ready tasks the scheduler determines the set of tasks with the highest priority. 3) From this set of highest priorty tasks the scheduler chooses that one, which is the oldest, i.e. that one with the lowest activation time.

That's all, isn't it? But remember that for BCC2 the tasks are non-preemptive and for ECC2 preemptions are allowed.

Best reagrds,

Olaf Barheine

hi,

sorry if i asked u in wrong manner....

thanks for the needful reply. please tell me any other things i need to concenrate for imlementing it.now iam doing the analysis for implementing in our RTOS with our team members.

with regards, Alagusakthi