[ECOS] Efficient way to wake up a task...

[ECOS] Efficient way to wake up a task...

[Guilly A]

Hi
I need to wake up a task after an interruption handling.
I am wondering which is the more efficient way to do that :
1- suspend the task and resume it in the ISR
2- make the task wait forever for a flag and set the flag in the ISR
3- use mailboxes.

On pSos, I used an event sending to wake up my task. I heard it was the 
fastest way and lowest memory cost do do it, compared to mailbox. But I had 
no evidence about it, I believed it naively.
I don't know how is it for eCos.

Thank you for your advices.

Rq : the task to be waken has the highest priority of my system, and in the 
ISR I just copy a 256bytes long buffer to a static buffer and send the 
wake-up signal...

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Re: [ECOS] Efficient way to wake up a task...

[Andrew Lunn]

On Wed, Jun 22, 2005 at 04:29:42PM +0000, Guilly A wrote:
> Hi
> I need to wake up a task after an interruption handling.
> I am wondering which is the more efficient way to do that :
> 1- suspend the task and resume it in the ISR
> 2- make the task wait forever for a flag and set the flag in the ISR
> 3- use mailboxes.
> 
> On pSos, I used an event sending to wake up my task. I heard it was the 
> fastest way and lowest memory cost do do it, compared to mailbox. But I had 
> no evidence about it, I believed it naively.
> I don't know how is it for eCos.
> 
> Thank you for your advices.

You should probably do the copy in the ISR. You then need to return
CYG_ISR_CALL_DSR so that a DSR is called. The DSR can then post on a
semaphore which will awaken the thread waiting on the semaphore.

        Andrew

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