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Date: Tue, 26 Aug 2008 08:17:48 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals.
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To: qemu-devel@nongnu.org
Cc: xen-devel@lists.xensource.com, Gerd Hoffmann <kraxel@redhat.com>

Ian Jackson wrote:
> Gerd Hoffmann writes ("Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals."):
>   
>> What this would be useful for?  The termination signals usualy one-shot
>> anyway, so I don't see any advantage in doing the pipe-to-self trick.
>>     
>
> The point is that then they can interrupt select().
>   

The race I know of is that you may get an aio signal completion before 
select but after you've already qemu_aio_poll()'d.  In practice, we only 
sleep for 10ms at a time in select() so the race is handled by that.  If 
we wanted to increase the amount of time we slept, we would have to 
handle this race.

In KVM, we sleep for 1s in select() and use signalfd() to receive the 
aio notifications.  For older hosts, we emulate signalfd using a thread 
and the pipe-to-self trick.

Regards,

Anthony Liguori

> Ian.
>
>
>