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

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

Hello John and all!

On 27 January 2010 17:37, John Dallaway wrote:

> Try moving "edf_info" to be immediately following "priority" in
> CYG_SCHEDTHREAD_SCHEDIMP_MEMBERS so that the ordering of members in
> cyg_thread match the ordering in the Cyg_Thread class.
>
> I hope this helps...
>
> John Dallaway
> eCos maintiner

Tried, does not have any positive effect, output is the same.

Now, I want to describe all of my main steps for discussion. If there
is no solution, then, I think, I would better to move to another way
to *deliver* EDF specific information to schedule method.

So, in ktypes.h I have:

> typedef struct cyg_edf_info_t
> {
>	cyg_count32 deadline;
>	cyg_count32 wcet;
>	cyg_count32 period;
> };

In kapidata.h I added:

> #elif defined(CYGSEM_KERNEL_SCHED_EDF)
> # define CYG_SCHEDTHREAD_SCHEDIMP_MEMBERS    \
>    cyg_thread *next;                                                        \
>    cyg_thread *prev;                                                        \
>    cyg_priority_t      priority;             /* current thread priority */  \
>    struct cyg_edf_info_t * edf_info;
> #else
> # error Undefined scheduler type

In Cyg_SchedThread_Implementation class of edf.hxx I added *edf_info*:

> class Cyg_SchedThread_Implementation
>    : public Cyg_DNode_T<Cyg_Thread>
> {
>    friend class Cyg_Scheduler_Implementation;
>    friend class Cyg_ThreadQueue_Implementation;

> protected:
>    cyg_priority        priority;       // current thread priority
>    struct cyg_edf_info_t * edf_info; // added by me
> ...
> }

In the constructor of Cyg_SchedThread_Implementation class at edf.cxx
file, I added followings:

> Cyg_SchedThread_Implementation::Cyg_SchedThread_Implementation
> (
>    CYG_ADDRWORD sched_info
> )
> {
>    CYG_REPORT_FUNCTION();
>    CYG_REPORT_FUNCARG1("sched_info=%08x", sched_info);
>    edf_info = (cyg_edf_info_t *) &sched_info;
>    priority = (cyg_priority) edf_info->deadline;
>
>    CYG_TRACE1(1, "edf_info->deadline = %d", edf_info->deadline);
>    CYG_TRACE1(1, "edf_info->wcet = %d", edf_info->wcet);
>    CYG_TRACE1(1, "edf_info->period = %d", edf_info->period);
> ...
> }

In my eCos application I am passing arguments in these way:

> #include <cyg/kernel/ktypes.h>
> ...
> void cyg_user_start(void)
> {
>	struct cyg_edf_info_t my_edf_info_A = {4, 11, 12};
>	struct cyg_edf_info_t my_edf_info_B = {5, 21, 22};
>
>	cyg_thread_create((cyg_addrword_t) &my_edf_info_A, simple_program, (cyg_addrword_t) 0,
>		"Thread A", (void *) stack[0], 32768,
>		 &simple_threadA, &thread_s[0]);
>	cyg_thread_create((cyg_addrword_t) &my_edf_info_B, simple_program, (cyg_addrword_t) 1,
>		"Thread B", (void *) stack[1], 32768,
>		&simple_threadB, &thread_s[1]);
>
>	printf("Threads are created\n");
>	cyg_thread_resume(simple_threadA);
>	cyg_thread_resume(simple_threadB);
> }

And output which I am getting is:

> TRACE: edf.cxx [602] Cyg_SchedThread_Implementation::Cyg_SchedThread_Implementation()   'edf_info->deadline = 31'
> TRACE: edf.cxx [603] Cyg_SchedThread_Implementation::Cyg_SchedThread_Implementation()   'edf_info->wcet = 0'
> TRACE: edf.cxx [604] Cyg_SchedThread_Implementation::Cyg_SchedThread_Implementation()   'edf_info->period = 0'

> TRACE: edf.cxx [602] Cyg_SchedThread_Implementation::Cyg_SchedThread_Implementation()   'edf_info->deadline = 10'
> TRACE: edf.cxx [603] Cyg_SchedThread_Implementation::Cyg_SchedThread_Implementation()   'edf_info->wcet = 0'
> TRACE: edf.cxx [604] Cyg_SchedThread_Implementation::Cyg_SchedThread_Implementation()   'edf_info->period = 0'

> TRACE: cstartup.cxx [91] void cyg_iso_c_start()   'Resuming cyg_libc_main_thread'
> TRACE: kapi.cxx [1238] void Cyg_Check_Structure_Sizes::Cyg_Check_Structure_Sizes()    'Size of C struct cyg_thread != size of C++ struct Cyg_Thread'
> ASSERT FAIL: <1> kapi.cxx [1250] Cyg_Check_Structure_Sizes::Cyg_Check_Structure_Sizes()    Size check failed
> ASSERT FAIL: kapi.cxx [1250] Cyg_Check_Structure_Sizes::Cyg_Check_Structure_Sizes()    Size check failed

I hope these codes and outputs could help to catch the bug. Any idea,
comment appreciated!

Regards,
Nodir.

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