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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Tue, 29 Nov 2016 16:45:47 +0100
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Subject: Re: [Qemu-devel] Linux kernel polling for QEMU
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To: Andrew Jones <drjones@redhat.com>, Fam Zheng <famz@redhat.com>
Cc: Eliezer Tamir <eliezer.tamir@linux.intel.com>, "Michael S. Tsirkin" <mst@redhat.com>, qemu-devel@nongnu.org, Jens Axboe <axboe@fb.com>, Christian Borntraeger <borntraeger@de.ibm.com>, Stefan Hajnoczi <stefanha@redhat.com>, Davide Libenzi <davidel@xmailserver.org>, Christoph Hellwig <hch@lst.de>



On 29/11/2016 16:24, Andrew Jones wrote:
> While we have a ppoll audience, another issue with the current polling
> is that we can block with an infinite timeout set (-1), and it can
> actually end up being infinite, i.e. vcpus will never run again. I'm
> able to exhibit this with kvm-unit-tests.

This should only happen outside the big QEMU lock, otherwise it's a bug.

Paolo

> For these rare cases where
> no other timeout has been selected, shouldn't we have a default timeout?
> Anyone want to pick a number? I have a baseless compulsion to use 10 ms...