Re: [Xenomai-help] Replacement for rt_save_flags_and_cli

["Ignacio García Pérez" <iggarpe@domain.hid>]

Jan Kiszka wrote:

>Ignacio García Pérez wrote:
>  
>
>>>But: both primitives are rather low-level. Do you really need that
>>>"hard" locks? What are you synchronising this way, IRQ handlers with
>>>tasks, tasks with other tasks?
>>>
>>>
>>>      
>>>
>>An IRQ handler with a task.
>>
>>Yeah, I know I could just use rt_intr_disable on that interrupt object,
>>but for reasons too long to explain, the it is encapsulated in a piece
>>of code and I'd rather not allow other code to see it. Probably not a
>>good design but at this stage of the port, I'd like to get it working
>>under xenomai with as little modifications as possible.
>>
>>Another place I've used it sometimes is substituting a mutex for very
>>short pieces of code such as:
>>
>>cli()
>>a = b + c;
>>sti()
>>
>>It is usually more efficient that using a mutex, and this may be
>>important in low-end processors with little horsepower.
>>
>>    
>>
>
>Agree. But even when developing for a low-end UP system, it's good style
>to use spinlocks (IRQ: xnlock_get, task: xnlock_get_irqsave) for it.
>They will cause the same code to be generated on UP, but will continue
>to work in case more CPUs pop up someday...
>  
>
Yup. Thank you for the tip. I have never worked with MP and never though
of that problem.

>>Man, you just read my mind :-)
>>
>>I just have to say it:
>>
>>1- It is amazing that fusion has progressed from conception to its
>>actual usable, stable state in such a short time.
>>
>>2- In general, I appreciate good design and robustness over efficiency
>>and other issues, but IMHO, for real-time systems it must be the number
>>one priority, which I'm not sure it was in the "formerly related
>>project". Too many large changes in too many time.
>>
>>3- The patent issue may not be a priority in the academic world, but it
>>definitely is for industrial applications.
>>
>>    
>>
>
>I generally consider the last topic as a psychological issue: people in
>industry feel better when they get farther away from well-known mined
>places - although the whole area is full of more or less effective mines
>these days. As only few minelayers really try to trigger them but rather
>use them more subtle, it's an issue, though.
>  
>
Well, actually I agree. I'm in the industry and I'm not that worried
about the patent issue. What troubled me actually was not the fact that
the "formerly related project" overrided the adeos protection, but
rather the fact that the deceision seemed (to me) somewhat unilateral.

Nacho.