[Beremiz-devel] Calculate greatest_tick_count__

[Beremiz-Devel mailing list]

Hi, all!

I have: 2 periodic task with time 10 and 3 ms.
Code:

1) config.c :
unsigned long long common_ticktime__ = 1000000ULL; /*ns*/
unsigned long greatest_tick_count__ = (unsigned
long)18446744073709551601UL; /*tick*/
// greatest_tick_count__ = (unsigned long)0xFFFFFFFFFFFFFFF1
// for main target unsigned long = 32 bit -> greatest_tick_count__ =
0xFFFF FFF1 = 4294967281 (dec)

2) plc_main.c:
unsigned long __tick = 0;
void __run(void)
{
     __tick++;
     if (greatest_tick_count__)
         __tick %= greatest_tick_count__;
...
     config_run__(__tick);
...
}

3) resource1.c:
void RESOURCE1_run__(unsigned long tick) {
   TASK1 = !(tick % 10);
   TASK2 = !(tick % 3);
   if (TASK1) {
     PROGRAM_DO1_body__(&INSTANCE1);
   }
   if (TASK2) {
     PROGRAM_DO2_body__(&INSTANCE2);
   }
}

What do We see when __tick = greatest_tick_count__?
First. __tick = 0
Second. Call TASK1 and TASK2.
Third. Invalid period calls TASK1

Time diagram:
__tick = 4294967270. Call TASK1 (period = 10 ms)
__tick = 4294967271. Call TASK2 (period = 3 ms)
__tick = 4294967274. Call TASK2 (period = 3 ms)
__tick = 4294967277. Call TASK2 (period = 3 ms)
__tick = 4294967280. Call TASK1 (period = 10 ms) Call TASK2 (period = 3 ms)

Moment: __tick = greatest_tick_count__ = 4294967281 -> __tick == 0

__tick = 0. Call TASK1 (period = 10 ms) Error! Delta TASK1 (10 ms) = 1.
                  Call TASK2 (period = 3 ms)  Error! Delta TASK2 (3 ms) = 1

__tick = 3. Call TASK2 (period = 3 ms)
__tick = 6. Call TASK2 (period = 3 ms)
__tick = 9. Call TASK2 (period = 3 ms)
__tick = 10. Call TASK1 (period = 10 ms)

It's a bag?

Regards,

Aleksandr Safronov!


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[Beremiz-Devel mailing list]

 Hi Aleksandr


 Yes, the implementation of periodic tasks is not strictly correct when the
timer overflows.

 To be honest I have always considered that the currently taken  approach to
implement periodic tasks is not ideal. It needs to be completely
revamped/changed. I know how I would like to do it, but once again it implies
changes to all the systems that provide runtime support for matiec compiled
programs, so I have never bothered fixing this.




 Cheers,

       Mario.







On Monday, April 09, 2018 15:12:41 [hidden email] wrote:

> Hi, all!
>
> I have: 2 periodic task with time 10 and 3 ms.
> Code:
>
> 1) config.c :
> unsigned long long common_ticktime__ = 1000000ULL; /*ns*/
> unsigned long greatest_tick_count__ = (unsigned
> long)18446744073709551601UL; /*tick*/
> // greatest_tick_count__ = (unsigned long)0xFFFFFFFFFFFFFFF1
> // for main target unsigned long = 32 bit -> greatest_tick_count__ =
> 0xFFFF FFF1 = 4294967281 (dec)
>
> 2) plc_main.c:
> unsigned long __tick = 0;
> void __run(void)
> {
>      __tick++;
>      if (greatest_tick_count__)
>          __tick %= greatest_tick_count__;
> ...
>      config_run__(__tick);
> ...
> }
>
> 3) resource1.c:
> void RESOURCE1_run__(unsigned long tick) {
>    TASK1 = !(tick % 10);
>    TASK2 = !(tick % 3);
>    if (TASK1) {
>      PROGRAM_DO1_body__(&INSTANCE1);
>    }
>    if (TASK2) {
>      PROGRAM_DO2_body__(&INSTANCE2);
>    }
> }
>
> What do We see when __tick = greatest_tick_count__?
> First. __tick = 0
> Second. Call TASK1 and TASK2.
> Third. Invalid period calls TASK1
>
> Time diagram:
> __tick = 4294967270. Call TASK1 (period = 10 ms)
> __tick = 4294967271. Call TASK2 (period = 3 ms)
> __tick = 4294967274. Call TASK2 (period = 3 ms)
> __tick = 4294967277. Call TASK2 (period = 3 ms)
> __tick = 4294967280. Call TASK1 (period = 10 ms) Call TASK2 (period = 3 ms)
>
> Moment: __tick = greatest_tick_count__ = 4294967281 -> __tick == 0
>
> __tick = 0. Call TASK1 (period = 10 ms) Error! Delta TASK1 (10 ms) = 1.
>                   Call TASK2 (period = 3 ms)  Error! Delta TASK2 (3 ms) = 1
>
> __tick = 3. Call TASK2 (period = 3 ms)
> __tick = 6. Call TASK2 (period = 3 ms)
> __tick = 9. Call TASK2 (period = 3 ms)
> __tick = 10. Call TASK1 (period = 10 ms)
>
> It's a bag?
>
> Regards,
>
> Aleksandr Safronov!
>
>
> ----------------------------------------------------------------------------
> -- Check out the vibrant tech community on one of the world's most
> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
> _______________________________________________
> Beremiz-devel mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/beremiz-devel

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[Beremiz-Devel mailing list]

Hi,Mario,  Aleksandr

Why  greatest_tick_count__ is not LCM of all task periods?

In case of LCM everythink would work fine...

Best regards,

Paul Beltyukov

2018-04-09 18:44 GMT+05:00 <[hidden email]>:

 Hi Aleksandr


 Yes, the implementation of periodic tasks is not strictly correct when the
timer overflows.

 To be honest I have always considered that the currently taken  approach to
implement periodic tasks is not ideal. It needs to be completely
revamped/changed. I know how I would like to do it, but once again it implies
changes to all the systems that provide runtime support for matiec compiled
programs, so I have never bothered fixing this.




 Cheers,

       Mario.

On Monday, April 09, 2018 15:12:41 [hidden email] wrote:
> Hi, all!
>
> I have: 2 periodic task with time 10 and 3 ms.
> Code:
>
> 1) config.c :
> unsigned long long common_ticktime__ = 1000000ULL; /*ns*/
> unsigned long greatest_tick_count__ = (unsigned
> long)18446744073709551601UL; /*tick*/
> // greatest_tick_count__ = (unsigned long)0xFFFFFFFFFFFFFFF1
> // for main target unsigned long = 32 bit -> greatest_tick_count__ =
> 0xFFFF FFF1 = 4294967281 (dec)
>
> 2) plc_main.c:
> unsigned long __tick = 0;
> void __run(void)
> {
>      __tick++;
>      if (greatest_tick_count__)
>          __tick %= greatest_tick_count__;
> ...
>      config_run__(__tick);
> ...
> }
>
> 3) resource1.c:
> void RESOURCE1_run__(unsigned long tick) {
>    TASK1 = !(tick % 10);
>    TASK2 = !(tick % 3);
>    if (TASK1) {
>      PROGRAM_DO1_body__(&INSTANCE1);
>    }
>    if (TASK2) {
>      PROGRAM_DO2_body__(&INSTANCE2);
>    }
> }
>
> What do We see when __tick = greatest_tick_count__?
> First. __tick = 0
> Second. Call TASK1 and TASK2.
> Third. Invalid period calls TASK1
>
> Time diagram:
> __tick = 4294967270. Call TASK1 (period = 10 ms)
> __tick = 4294967271. Call TASK2 (period = 3 ms)
> __tick = 4294967274. Call TASK2 (period = 3 ms)
> __tick = 4294967277. Call TASK2 (period = 3 ms)
> __tick = 4294967280. Call TASK1 (period = 10 ms) Call TASK2 (period = 3 ms)
>
> Moment: __tick = greatest_tick_count__ = 4294967281 -> __tick == 0
>
> __tick = 0. Call TASK1 (period = 10 ms) Error! Delta TASK1 (10 ms) = 1.
>                   Call TASK2 (period = 3 ms)  Error! Delta TASK2 (3 ms) = 1
>
> __tick = 3. Call TASK2 (period = 3 ms)
> __tick = 6. Call TASK2 (period = 3 ms)
> __tick = 9. Call TASK2 (period = 3 ms)
> __tick = 10. Call TASK1 (period = 10 ms)
>
> It's a bag?
>
> Regards,
>
> Aleksandr Safronov!
>
>
> ----------------------------------------------------------------------------

> -- Check out the vibrant tech community on one of the world's most

> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
> _______________________________________________
> Beremiz-devel mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/beremiz-devel


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[Beremiz-Devel mailing list]

Sorry, Ishould say LCM/GCD instead of LCM.

Best regards,

Paul Beltyukov

2018-04-10 14:35 GMT+05:00 <[hidden email]>:

Hi,Mario,  Aleksandr

Why  greatest_tick_count__ is not LCM of all task periods?

In case of LCM everythink would work fine...

Best regards,

Paul Beltyukov

2018-04-09 18:44 GMT+05:00 <[hidden email]>:

 Hi Aleksandr


 Yes, the implementation of periodic tasks is not strictly correct when the
timer overflows.

 To be honest I have always considered that the currently taken  approach to
implement periodic tasks is not ideal. It needs to be completely
revamped/changed. I know how I would like to do it, but once again it implies
changes to all the systems that provide runtime support for matiec compiled
programs, so I have never bothered fixing this.




 Cheers,

       Mario.

On Monday, April 09, 2018 15:12:41 [hidden email] wrote:
> Hi, all!
>
> I have: 2 periodic task with time 10 and 3 ms.
> Code:
>
> 1) config.c :
> unsigned long long common_ticktime__ = 1000000ULL; /*ns*/
> unsigned long greatest_tick_count__ = (unsigned
> long)18446744073709551601UL; /*tick*/
> // greatest_tick_count__ = (unsigned long)0xFFFFFFFFFFFFFFF1
> // for main target unsigned long = 32 bit -> greatest_tick_count__ =
> 0xFFFF FFF1 = 4294967281 (dec)
>
> 2) plc_main.c:
> unsigned long __tick = 0;
> void __run(void)
> {
>      __tick++;
>      if (greatest_tick_count__)
>          __tick %= greatest_tick_count__;
> ...
>      config_run__(__tick);
> ...
> }
>
> 3) resource1.c:
> void RESOURCE1_run__(unsigned long tick) {
>    TASK1 = !(tick % 10);
>    TASK2 = !(tick % 3);
>    if (TASK1) {
>      PROGRAM_DO1_body__(&INSTANCE1);
>    }
>    if (TASK2) {
>      PROGRAM_DO2_body__(&INSTANCE2);
>    }
> }
>
> What do We see when __tick = greatest_tick_count__?
> First. __tick = 0
> Second. Call TASK1 and TASK2.
> Third. Invalid period calls TASK1
>
> Time diagram:
> __tick = 4294967270. Call TASK1 (period = 10 ms)
> __tick = 4294967271. Call TASK2 (period = 3 ms)
> __tick = 4294967274. Call TASK2 (period = 3 ms)
> __tick = 4294967277. Call TASK2 (period = 3 ms)
> __tick = 4294967280. Call TASK1 (period = 10 ms) Call TASK2 (period = 3 ms)
>
> Moment: __tick = greatest_tick_count__ = 4294967281 -> __tick == 0
>
> __tick = 0. Call TASK1 (period = 10 ms) Error! Delta TASK1 (10 ms) = 1.
>                   Call TASK2 (period = 3 ms)  Error! Delta TASK2 (3 ms) = 1
>
> __tick = 3. Call TASK2 (period = 3 ms)
> __tick = 6. Call TASK2 (period = 3 ms)
> __tick = 9. Call TASK2 (period = 3 ms)
> __tick = 10. Call TASK1 (period = 10 ms)
>
> It's a bag?
>
> Regards,
>
> Aleksandr Safronov!
>
>
> ----------------------------------------------------------------------------

> -- Check out the vibrant tech community on one of the world's most

> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
> _______________________________________________
> Beremiz-devel mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/beremiz-devel


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