[okl4-developer] IPC timeouts

[Sergio Ruocco]

Hi,

Besides the already-given explanations ("a suitable way to find good timeouts values was never found" and "in this way the kernel API does not depend on timers"), another good reason for the removal is that IPC timeouts require(d) the kernel to queue the thread in a timeout-waiting list, to periodically check if any timeout expired, and if so dequeue the threads and abort their IPCs. Since a functionality similar to IPC timeouts can be achieved at user-level, this overhead can be shaved from the kernel.

	Sergio

Jorge Torres wrote:
> Hi Peter,
> 
> I'm not sure if the following is correct, but one reason I can think of, and
> it has been talked about is that IPC timeouts can be  developed outside the
> microkernel by a timeout server, last person that asked this, pointed that
> such thing could only be possible if IPC receiver receives from anythread,
> which I find true, but instead of taking IPC timeouts back into the kernel,
> it should provide the mechanisms for IPC timeouts to be possibly implemented
> outside, anyways,  having IPC timeouts inside the microkernel tights it to
> the platform timer, and in ideal terms, access to system's timer should
> happen only trough a user-level timer driver,  I'm sure there is a much more
> accurate answer to this by Ben Leslie on the list archives.
> 
> Cheers,
> 
> Jorge
> 
> On 10/31/07, Peter Nguyen <peter.nguyen at adelaide.edu.au> wrote:
>> Hi,
>>
>> In a post that i sent about IPC timeouts, it was mentioned that this was
>> removed.  I was wondering whether anyone can give me a reason why this
>> decision was made, just out of curiosity.
>>
>> Thanks
>> Peter N
>>
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>>
> 
> 
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-- 

Sergio Ruocco, PhD                                       Research Fellow
mail:ruocco at disco.unimib.it / sergio.ruocco at gmail.com        NOMADIS Lab
phone: +39-02-6448-7914               Mobile, embedded real-time systems
skype: 'sergioruocco'  Dip. di Informatica, Sistemistica e COmunicazione
Building U14, room 1003  Università degli Studi di Milano-Bicocca, Italy

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