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From:	bob <bob AT icanprogram DOT com>
To:	cygwin AT cygwin DOT com
Subject:	re: signalfd support
Date:	Tue, 16 Oct 2012 08:22:07 -0400
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============
I'm on the list in digest mode,  so I don't know how to thread this response 
properly.
============

Thanks to all who have taken time to respond so far.

I am already using POSIX shared memory in the application I am trying to port 
to Cygwin.   The fifos are simply used to synchronize access to the shared 
memory and to provide a convenient select()/poll()'able interface to multiplex 
things.   The only thing presented to the fifo is an integer index value.   The 
actual message data itself is in shared memory.    

In a previous posting a few weeks back I presented some test code which 
illustrated the performance deficit in the current Cygwin fifo implementation (2 
orders of magnitude slower than Linux on same hardware).      It was this 
performance issue that led me on a search for an alternative synchronization 
mechanism that still allowed for multiplexing via select()/poll().      As far 
as I can tell neither POSIX semaphores,  POSIX message queues or sigwaitinfo() 
can meet this multiplex criteria.     However,  the combination of real time 
queueable  signals and signalfd (or eventfd) could.

As I understand things Cygwin supports real time signals,   but doesn't yet 
support signalfd (or eventfd) functionality.

bob

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