code review: help implementing clock_montonic

[zack_on_the_speed_chanel]

> This ticket mostly references the need for a test. Have you tried to
> write a test for the missing functionality?
>
How I made a test for it was to create the timer using timer_create() . It also said to use a previous test with timer_realtime and i tested it with  sometime similar to PSXtimer02 test. I  got a invalid argument error when I tried it. Joel told me i also have to impliment the monotonic clock


>his math doesn't make sense to me. explain what you're trying to do?

I wanted calculate the remaining time with the timespec. I assumed that the timespec contained the total time seconds+miliseconds. I knew that a cpu tick is an uint32. So i converted to timspec

      remaining = (uint32_t) ( ptimer->Timer.expire - now );

to something like
expire->tv.nsec+expire->tv.sec  - spec->tv.nsec+spec->tv.sec);


> > Yes, settime is an important function to distinguish between MONOTONIC
> and REALTIME cases. That is going to be tricky to think through.

Where do you want to check the clock type. I though I only need to distinguish between both when getting the value of the clock. I don't exactly know what needs to be done me being really new to posix and operating system development.



Zack


‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Tuesday, May 11, 2021 6:23 AM, Gedare Bloom <gedare at rtems.org> wrote:

> On Fri, May 7, 2021 at 12:53 PM zack_on_the_speed_chanel
> zack_on_the_speed_chanel at protonmail.ch wrote:
>
> > hello,
> > Currenttly i'm trying to implement the clock_monotonic which was part of ticket #3889. So far these are the changes are as follows
>
> This ticket mostly references the need for a test. Have you tried to
> write a test for the missing functionality?
>
> > ptimer->clock_type= &clock_id;
> > in the timer create i added a field for the timer id and saved it when the timer was made. Then in getttime I used the appropriate timers to get the time.
> > for example.
> > if (ptimer->clock_type ==CLOCK_REALTIME) {
> > Per_CPU_Control *cpu;
> > struct timespec spec;
> > struct timespec expire;
> >
> >     cpu = _POSIX_Timer_Acquire_critical( ptimer, &lock_context );
> >
>
> Maybe move the clock_type check to here?
>
> >     _TOD_Get(spec);
> >       _Timespec_From_ticks( expire, &ptimer->Timer.expire);
> >
> >
> >     if (spec->tv.nsec+spec->tv.sec > expire->tv.nsec+expire->tv.sec ) {
> >
> >       remaining = (uint32_t) (expire->tv.nsec+expire->tv.sec  - spec->tv.nsec+spec->tv.sec);
> >
>
> this math doesn't make sense to me. explain what you're trying to do?
>
> >     } else {
> >       remaining = 0;
> >     }
> >
> >     _Timespec_From_ticks( remaining, &value->it_value );
> >     value->it_interval = ptimer->timer_data.it_interval;
> >
> >     _POSIX_Timer_Release( cpu, &lock_context );
> >     return 0;
> >
> >
> > }
> > Here i made two separate cases for getting the time. Also joel told me to I feel that it is a bit redundant to call everything using timespec to calculating remaining time and then just use timespec_From_ticks to get the time. It was a recommendation from Joel. Did I make the correct change. Also I assume that Delete does not need any changes because It does not require any measuring of time. Is there anything i need to change for timer_settime?
>
> Yes, settime is an important function to distinguish between MONOTONIC
> and REALTIME cases. That is going to be tricky to think through.
>
> > Thanks
> > Zack
> >
> > devel mailing list
> > devel at rtems.org
> > http://lists.rtems.org/mailman/listinfo/devel