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Date: Thu, 29 Mar 2012 14:36:00 +0100
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From: Stefan Hajnoczi <stefanha@gmail.com>
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Subject: Re: [Qemu-devel] [PATCH 0/2] ide: convert pio code path to
 asynchronous I/O
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To: Chris Webb <chris@arachsys.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Richard Davies <richard@arachsys.com>, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>, qemu-devel@nongnu.org, Zhi Yong Wu <wuzhy@cn.ibm.com>, Paolo Bonzini <pbonzini@redhat.com>

On Thu, Mar 29, 2012 at 12:30 PM, Chris Webb <chris@arachsys.com> wrote:
> Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> writes:
>
>> Chris and Richard: Please test this to confirm that it fixes the hang you
>> reported.
>
> We've been testing this (v1 against qemu-kvm 1.0) today, and it's looking
> very good. Thanks!
>
> The lock-ups during boot no longer happen, and if you severely throttle
> (1MB/s, 100 req/s) a guest in the middle of a big dd, there are lots of
> nasty kernel messages as it falls back to pio mode, but the guest doesn't
> lock up and qemu remains responsive.

Thanks for trying it out.

Regarding the guest kernel errors, they may be timeouts.  The guest
may consider the IDE controller buggy/dead due to how long requests
take to complete under severe throttling.  There's not much that can
be done about that, I think.  If you think the guest errors are due to
something else though, please post the error messages.

Stefan