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[Xen-devel] Re: [Qemu-devel] [PATCH 01/13] Handle terminating signals.

Ian Jackson wrote:
Gerd Hoffmann writes ("Re: [Qemu-devel] [PATCH 01/13] Handle terminating 
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.


Anthony Liguori


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