IPC Timeouts

Martin Pohlack mp26 at os.inf.tu-dresden.de
Wed Feb 23 19:41:40 CET 2005

Ronald Aigner wrote:


>  To imitate the concurrent waiting for an IPC or timer event one could set
> up a timer with the kernel and inculde the "timer-source" into the receive
> scope of the wait IPC.  Timer events can be dropped if the receiver is not
> ready.  This would also simplify the tasks using IPC timeouts as timer
> event source.

I see one problem with this:


I use finite timeouts in a library emulating keyboard repeat behaviour 
(you press the key -> one press event is generated, you keep the key 
pressed -> after 250 ms another event is generated every 100 ms until 
you release the key).

This is implemented with IPC-Recv from an event thread with the timeouts 


The setup and start of the timer and the ipc operation in this scenario 
is atomic.  If I would have to setup and start the timer independently 
of the IPC I could be interupted and/or delayed in-between if no other 
meassures (e.g. delayed preemption) would be taken.

There could be similar more critical examples (although I think that a 
spongy keyboard is bad enough).


Martin Pohlack
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