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Date: Fri, 18 Apr 2008 14:46:25 -0300
From: Marcelo Tosatti <mtosatti@redhat.com>
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Subject: [Qemu-devel] Re: [PATCH 3/3] Implement linux-aio backend
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To: Anthony Liguori <aliguori@us.ibm.com>
Cc: kvm-devel@lists.sourceforge.net, qemu-devel@nongnu.org

On Fri, Apr 18, 2008 at 10:18:33AM -0500, Anthony Liguori wrote:
> >Sleeping in the context of vcpu's is extremely bad (eg virtio-block
> >blocks in write() throttling which kills performance). It should wait
> >on IO completions instead (qemu-kvm.c creates a pthread "waitqueue" to
> >resolve that issue).
> >
> >Other than that looks fine to me, will give it a try.
> >  
> 
> FWIW, I'm not getting wonderful results in KVM.  It's hard to tell 
> though because time seems wildly inaccurate (even with kvm clock in the 
> guest).  The time issue appears unrelated to this set of patches.

Oh, you won't get completion signals on the aio eventfd. You might want
to try the select-with-timeout() stuff.

Will submit that with proper signalfd emulation shortly.