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Re: What means of word 'quesue' in this RTOS description?

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On 7/26/2015 7:27 AM, Les Cargill wrote:
> Tim Wescott wrote:
>> On Fri, 24 Jul 2015 20:52:51 -0500, Les Cargill wrote:
>>
>>> Tim Wescott wrote:
>>>> On Fri, 24 Jul 2015 04:12:23 -0700, Robert Willy wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> I read an online tutorial on RTOS, see below dot line please.
>>>>> I am not clear about what is for the word 'queue' in the first line.
>>>>> Does it mean a task queue?
>>>>>
>>>>>
>>>>> Thanks in advance.
>>>>> ....................
>>>>> The use of a queue allows the medium priority task to block until an
>>>>> event causes data to be available - and then immediately jump to the
>>>>> relevant
>>>>>    function to handle the event. This prevents wasted processor cycles
>>>>>    -
>>>>>    in contrast to the infinite loop implementation whereby an event
>>>>>    will only be processed once the loop cycles to the appropriate
>>>>>    handler.
>>>>
>>>> I'm not sure what you mean by "task queue".
>>>>
>>>> Generally, RTOS implementations don't bind a queue to any specific
>>>> task. Rather, the developer does so: anything can put messages into a
>>>> queue, anything can take messages off of a queue, and anything can pend
>>>> on a queue.  If the developer is wise, only one task takes things off
>>>> the queue, and there is a well-defined, small number (one is best) of
>>>> sources that put things on the queue.
>>>>
>>>> You arrange things so that the task that depends on the queue needs to
>>>> run if and only if there's a message on the queue, and you have the
>>>> task pend on the queue having a message available.
>>>>
>>>>
>>> One common method of referring to task/thread eligibility to run is to
>>> have a "ready queue" or a "waiting queue". This may not actually be a
>>> queue; it can be nothing more than a state in the set of task control
>>> blocks.
>>>
>>> Vhttp://www.qnx.com/developers/docs/660/index.jsp?topic=%
>> 2Fcom.qnx.doc.neutrino.prog%2Ftopic%2Foverview_Ready_queue.html
>>
>> That's not what the OP is talking about,
>
> Then I have no hope of finding what he's talking about.

The OP mistakenly called it a "task queue".  It's actually a "data FIFO"
supported as a first-class object by the OS.  As such, a *task* can
pend on it "efficiently" (moreso than spinning on it!)

> 1) "The use of a queue allows the medium priority task to block until
> an event causes data to be available" - mention of blocking, which is
> very much a "waiting queue"/"ready queue" sort of thing, although
> you have to wonder why medium priority matters.

Read the cited example.

> The big ambiguity is whether or not the queue is a data source/buffer
> or simply a wait/block structure.
>
> 2) The compare/contrast with The Big Loop.
>
> wait/ready queuing is as close as I can get with that mess.

Read the examples *preceding* the cited example.  :>

>  > but yes, I had forgotten that
>> terminology (please, please do not ask me why).
>>
>
> :)
>

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Thread

What means of word 'quesue' in this RTOS description? Robert Willy <rxjwg98@gmail.com> - 2015-07-24 04:12 -0700
  Re: What means of word 'quesue' in this RTOS description? Les Cargill <lcargill99@comcast.com> - 2015-07-24 07:47 -0500
  Re: What means of word 'quesue' in this RTOS description? Tim Wescott <seemywebsite@myfooter.really> - 2015-07-24 13:59 -0500
    Re: What means of word 'quesue' in this RTOS description? Grant Edwards <invalid@invalid.invalid> - 2015-07-24 19:34 +0000
    Re: What means of word 'quesue' in this RTOS description? Les Cargill <lcargill99@comcast.com> - 2015-07-24 20:52 -0500
      Re: What means of word 'quesue' in this RTOS description? Tim Wescott <seemywebsite@myfooter.really> - 2015-07-24 22:18 -0500
        Re: What means of word 'quesue' in this RTOS description? Les Cargill <lcargill99@comcast.com> - 2015-07-26 09:27 -0500
          Re: What means of word 'quesue' in this RTOS description? Don Y <this@is.not.me.com> - 2015-07-26 08:51 -0700
          Re: What means of word 'quesue' in this RTOS description? Tim Wescott <seemywebsite@myfooter.really> - 2015-07-26 16:23 -0500
    Re: What means of word 'quesue' in this RTOS description? upsidedown@downunder.com - 2015-07-25 08:57 +0300
  Re: What means of word 'quesue' in this RTOS description? Don Y <this@is.not.me.com> - 2015-07-24 12:34 -0700
    Re: What means of word 'quesue' in this RTOS description? Robert Willy <rxjwg98@gmail.com> - 2015-07-24 14:03 -0700
      Re: What means of word 'quesue' in this RTOS description? Don Y <this@is.not.me.com> - 2015-07-24 14:37 -0700

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