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Date: Tue, 26 Aug 2008 13:50:39 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating
	signals.
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To: qemu-devel@nongnu.org
Cc: xen-devel@lists.xensource.com, Ian Jackson <Ian.Jackson@eu.citrix.com>, Gerd Hoffmann <kraxel@redhat.com>

Jamie Lokier wrote:
> Leading to: why would (real) signals being used to collect AIO events
> anyway, if you don't have signalfd()?  If you've got a helper thread,
> just call aio_suspend() in the helper thread.

There is no helper thread when signalfd() is available.  The helper 
thread thing is only for backwards compatibility or for unices that 
don't support signalfd.  Plus, there are a lot of places that we use 
signals currently.

>   Then you can just
> deliver the AIO completion result to the relevant data structure or
> even move it off the waiting queue (pthread_mutex_lock is your
> friend), then wake the main waiting thread with byte written to its
> pipe.
>   

It's the queuing with threads where things start getting complicated and 
error prone.

Regards,

Anthony Liguori

> -- Jamie
>
>
>