Re: SCHED_FIFO and pthread_cond_broadcast

[Tadeus Prastowo <0x66726565@gmail.com>]

Hello,

On Fri, Jan 17, 2020 at 4:09 PM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
> It is a known issues and it is being tracked at BZ#11588 [1].

Thank you very much for your information.

> Currently
> condition variable does not have PI awareness (such as userland wait
> queues) and issues default futex wait/wake calls that do not take in
> consideration the waiters priority.
>
> There were an interesting discussion about how to make condition variables
> PI enabled [2], and currently there is no easy way to fulfil both POSIX
> requirements and PI expectation with current kernel futex primitives.
>
> Last Linux Plumbers Darren Hart presented an alternative conditional
> variable implementation [3] that enables PI awareness, but it has its
> own drawbacks (it has different semantic than POSIX conditional variable
> at API level and afaik it is subject the very issue the new glibc
> conditional variable implementation solved, discussed at [4]).
>
> If your usage does not require all the POSIX specification about partial
> ordering regarding signaling, you might consider use librtpi (your example
> seems to show the expected output adapating to use it).
>
> [1] https://sourceware.org/bugzilla/show_bug.cgi?id=11588
> [2] https://www.youtube.com/watch?v=D1hGc8qJCcQ&list=UL-cj2JDu_Ac4&index=1208
> [3] https://github.com/dvhart/librtpi
> [4] https://www.austingroupbugs.net/view.php?id=609

Thank you very much for your pointers.

Once again, thank you very much for your information.  I reallly appreciate it.

-- 
Best regards,
Tadeus