[ECOS] Re: how to implement EDF scheduling in eCos

[Nodir Kodirov <nodir dot qodirov at gmail dot com>]

Hi John, Fabian and all,

> Fabian wrote:
> ah, sorry - the first parameter is meant to be some kind of generic
> scheduler information parameter not necessarily a static priority. I
> should have taken a closer look into the documentation before my first
> comment.

Me too, I thought it to be priority. Thank you for light John! I am
following your advice.

Now, I added:

typedef struct
{
    cyg_tick_count deadline;
    cyg_tick_count wcet;
    cyg_tick_count period;
} cyg_edf_sched_info;
typedef cyg_edf_sched_info cyg_edf_sched_info_t;

to cyg/kernel/ktypes.h
Next, I built eCos library and linked my application to it. Run on my
x86 Advantech target board and it works fine.

Next, I defined additional member variable (to be used in
Cyg_SchedThread_Implementation class Constructor, to extract
[deadline, wcet and period] properties from *sched_info* generic
parameter and use it for schedule() method)
> cyg_edf_sched_info_t *thread_edf_info;
to Cyg_SchedThread_Implementation class, where we can define scheduler
specific members for threads (file src/sched/edf.hxx line #252). You
can have a look at the same place with mlqueue.hxx.

But, there is problem.
When I include thread_edf_info to Cyg_SchedThread_Implementation
class, I can build my eCos library, link it my eCos application and
port it to board. But, when I run eCos application in target board,
application halts after thread creation. However, I didn't modify any
place of neither Cyg_SchedThread_Implementation class constructor nor
cyg_thread_create() function yet.

So, my question is, can I modify Cyg_SchedThread_Implementation class
(just adding one more class member variable)?

Herein I have attached my simple eCos application source file also.
Note: in my target board application halts before printf("Threads are
created\n"); line.

Any help is highly appreciated!

Thanks,
Nodir.

> I was envisaging something like this:
>
> ?struct cyg_edf_sched_info_t {
> ? ?cyg_tick_count_t deadline;
> ? ?cyg_tick_count_t wcet;
> ? ?cyg_tick_count_t period;
> ?};
>
> ?cyg_edf_sched_info_t myinfo = {11, 12, 13};
> ?cyg_thread_create((cyg_addrword_t) &myinfo, simple_program, ...
>
> John Dallaway
> eCos maintainer

Attachment: edf_threads.c
Description: Binary data

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